SOME 2222 ‘25 2:2: 222222: 2.22222 2522' 23:2: 5032. 2202222322 2A 2222 22222: ‘ (2222 us 3:222: «222A A27 22222222232322 08 (3222232222 22.222 ,222222222 2:22.22 :22 2232222202222 222222222, 2222222223222 Thai: for £229 Dam of M. 3. MCI-€165.52 STATE COLLEGE 2.2220 92222-2222202” 2953 0-169 This is to certify that the thesis entitled Some Effects of Stand Density on Soil Moisture in a Red. Pine (Pinug resinosa Ait.) Plantation on Grayling Sand, Gravelly Phase, in Crawford County, Michigan presented by Lino Della-Bianca has been accepted towards fulfillment of the requirements for M. S. degreein Forestry Wfi Major professor Bantam—1953— . .. —‘-__ u--_. ‘ son: ms or 5mm mmsm on son. 1013211121: 111 A RED PINE (ans Erasmus; m.) PLANTATION on we sum, mm‘m, IN ammo comr, mam By 1.1m DEM-BIANCA - - A THEE Snbnitted to the School of Graduate Studies 'of Elohim State College of Agriculture and Applied Science in partial fulfill-mt or the requires-ante for the degree of HASTE 0F SCIENGI Department of Forestry 1953 10W Grateful acknowledgemnt is node to the U. 5. Forest Service for its sponsorship of this stub. Acknowledgement is given to Hr. Francis 42. Eyre, Chief, Division of Forest Management, U. 8. Forest Service, for originating the study. The author sdshes to express his sincere appreciation to Dr. Terrill D. Stevens, Head or the Departmt of Forestry, for his continuous inspiration, encouragement, and assistance in letters pertaining to this stair, and for his valuable guidance thro'nfinout w yen-s of study at Michigan State College. The author apresses gratitude to Dr. Robert E. Dils for valuable suggestion during the come of this stub. Gratitude is expressed talk. John L. trend, Research Center Leader, and [to 1%. Robert A. Balaton, Research Forester, of the Lake Stat. Frost kperinont Station Research Center at East Inning, Michigan, for their interest, suggestion, and cooperation throudmut the course of the stairs The author expresses thanks to Dr. George J. Bowen”, Dr. Uflliaa D. Baten, Dr. L. 'Earl Erickson, and Mr. Ivan I. Schneider of the Soil Science Depart-ant of Michigan State College for technical advice redered. Indebtedness is expressed to Mr. Edvnrd J. Kimm, fir. Jack Stubbs, Hr. Her-an Ziegler, and to n are, Maria, for their invaluable assistance in aceouplishing the field work during critical stages of 2 this stub. r - " 2.92:" (I; g- 8 1123*) sous m or STAND DEIBII‘Y’ on son. mm IN A mm m (PINUS 2123mm m.) mum: on We SAND, mm PHASE, IN mm) comm, MICHIGAN By Lino Della-Bianca MW Submitted to the School of Graduate Studies of mehigan State College of Agriculture and Applied Science in partial fulfilhent of the requirements. for the degree of m 0? SONG! Department of Forestry Year 1953 i e I fl W I.” 4.11.4 __ 1.1110 DELI-BIANCA m0! Thinning dense stands of red pine (m reeinosa Lit.) results in an increased rate of youth for the remaining trees in the stand. The nutrient supply from the area is made available in greater quantities for the remaining trees; hence, they are able to you at an increased rate. One of the youth factors thich is at a critically low level during some part of the growing season for red pine yowing on Grayling sand, gravel]: mass, in Crawford County, Michigan is the soil noisture supply. The nut-pot. of this study was to determine whether thinning . dense plantation of red pine, spaced 5:5, and M4 years old, into stands of varying levels of stocking would reduce a difference be- tween stands in the noisture content of the soil present in the stands. Research was also conducted with nylon electrical resistance units to determine “her or not they were suitable for use in Qrayling sand, gravelly phase, for determining the in 533 soil moisture content of the stands. Belated neasuremmts were taken of the cunnlative weekly rain- fall, weekly radial youth, and soil temperatures. The study was conducted in a red pine plantation yotdng on Qrayling sand, yavelly phase, on the Higgins lake State Fcrest in Elohim. The plantation had been thinned so as to produce stands of varying demity. The stands selected for the stub c ontained basal areas of 190, 120, and 80 square feet per acre, respectively. Additional neasurenents were taken fron an adjacent open field. . d r . u, .. s 2 o . 2. a \ . . . \2 t . e u . \_ I \ . I s s. a. . a I H i o . . . n . a . s _ . o u n . . . . . — 2 . . e. \ 2 o . . o . . x O . u n 2 e u . i . . a. I . . . u A. .1 . — a a . u .2 2 . .3... ‘— Bone of the most significant results of the study show that: 1. Plot 80, containing 80 square feet of basal area, had the bignest soil moisture content at the six inch depth 82.]; percent of the weeks during the growing season. 2. After June 20, 1953, the open field had the met soil noisture at the 36 inch depth. Soil moisture fluctuations tore yeatest in the open field. 3. Soil moisture fluctuations and differences between the plots were greatest firon July 18 to Augmt 22.. 1953. They occurred at the six inch depth. h. There was a yadual decrease in soil moisture at all three depths from April 1 to August 29, 1953. On August 29 the soil noisture supply use extremely low at all three depths. 5. Empirical field-calibration curves have been deve10ped for Grayling sand, yavelly phase. , 6. A separate empirical field-calibrated curve is needed for each depth to which units are interred. ‘ 7. The nylon electrical resistance units should be interred dry, preferably in the fall when Grayling sand tends to be dry. 8. Perhaps the best use of the nylon electrical resistance unit in a sand soil is as an indicator of broad relative soil noisture conditions rather than an actual moisture content. 9. Soil temperatures at all three depths in the Open field sore decidedly higher than the temperatures in am of the red pine 1310138 e 10. The general trend in order of decreasing soil temperatures at all three depths was plot 80, 120, and 190, contain- ing 80, 120, and 190 square feet of basal area per plot, respectively. ll. Radial youth began when the plots were at an approximate minimum tuperature of 127.5 '1". at the six inch depth; and minim temperature of hd‘r. at the 36 inch depth. 12. Plot 80 produced the best radial growth; plot 120 followed; and plot 190 showed the least radial growth. 13. Radial growth practically ceased in plot 190 by m, 25. ' ' 1h. The growth rate for dominant trees increases only slightly the: thinning are made. TABLE OF CONTENTS MOTION..................... SOMBIIFIDBUCEIHSOEPDISTURB........... mmorsonmisrmggyg.......... mormuas '3... Effects of Stand Density on Soil Hoisture. . DEMONOFTHEAREA................ Glinte..................... Agriculturalfiistory............... PlotDescription ................ BoilDesoriptionp................ WOFROCEDUBI................. Intalling the Nylon Electrical Resistance Units. Collecting Soil Samples men a Deep Snow lhntle 'ish'esent.................... Warhtallatiom............ laboratoryCalihratioanperinnts........ mun-S ....................... 2.. Soil Moisture and Snow Supply During Iete HinterandEarlySpring............. Vuiations in Soil Moisture Supply During the GrowingSeason ................. Soil Hodsture Trends as Indicated by the Nylon nostricalfiesistameflnits........... PACE Bfigflfifirp 37 39 56 69 Field Resistance-Moisture Calibration Curves Developed for the Nylon Electrical Resistance Unit for Use in Grayling Sand, Gravelly Phase . SoilTelperatureTrends............' - 3e- !ffects of Soil Hoisture an! Stand Density “meeeeeee smallwficnsmm . .. . mmcm....-... mm 0 PACE 79 83 87 912 100 103 H6033 l. 2. 3. 14. LIST OF IIJIBTRATIOIB Aerial photoyaph showing location of the red pine plantation.................................... Plot 190, showing the dense stocking of the stand 3 except for some bracken fem in a fee opening, only fungi you on the forest floor.................... Plot 120 in August, 1953. showing braehen fern you in the openings. Annual woods plants were plentiful inthis plot........................................... Plot 80 in August, 1953. The opening were quickly W“ by m..eee..e‘eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeo 5. Vegetative cover on the opm field consisted lost]: 6. 7. 9. 10. 11. 0: ”1:10 W.“ M ”not-fern".................... Field equipsent used during the installation of the ”1" .lmrica r‘ntmc. ml“...................... PAGE l7 19 21 22 28 Slit trench dug to determine depth of root concentrations 29 Intelling the nylon units necessitated the me of a piece of cardboard 2. hoop the soil in the order in inch it m moved................................... Taking wlon electrical resistance unit readings unier frigid tinter conditions. February 28, 1953..... Collecting soil samples fron Plot 80 in July........... faking radial youth usasuremnts with a dial gauge dendroneter. August 1953.............................. 30 31 38 .O...‘....I..‘ll OOOOQO-eloecbosaeo- ’OOboea. . covet-ocCIDVQQOOOICOO'so... A C..I'OC¢OOOOQQO~ l t a flannel-souaoeogg (‘ 'rn ' r f 2' | r- N O ' h r‘ OOQUOOOQOI-IOOOI . fi 7. 2.1 r r " 2 - Ieeev_ ( ‘l OI. see. so " . re 'W ‘ , 0... scene... 'C.........It. .- 0 fr 22‘ ‘Nqfi a . \ ,— -e l“. ‘._._. _...__—..- 12. 13. 1h. 15. 16. 17. 18. 19." 20. 21. 22 . 23. 25. Setup using No. 10 cans used in laboratory calibration of the nylon units. Cans had solid botton............................-........... Setup showing the perforated No. 10 can on supports, and the soil cans with perforated bottom used in the laboratory calibration experiments................... Plot 190 on February 28, 1953._........................ Plot 190 showing the snow cover existing at the end of hrch. March 31, 1953............................ Plot 120 showing the snow cover on March 31, 1953.... Plot 80 showing snow cover on March 31, 1953......... The-em belt concentrated on the north edge of the plantation. March 31, 1953.......................... Jack pine stand on March 31, 1953, showing dense net of unseen“.................................... leative weekly rainfall........................... Soil moisture expressed as percent of oven-dry weight Soil moisture exp‘eeeed as percent of oven-dry reign. Partial, soil profile in Plot 190 showing dense ms of roote...........................................u Partial soil profile in Plot 80...................... Partial soil profile in the open field showing the m. rOOt'eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee. P13 52 53 55 58 59 6o 67 9 C C O ‘ I u - Q Q I - - u , u * ; I .nD-IO.I...I.“ ‘.....".D’..'. .“-‘...II...... I‘.'.I...". q~u¢q0e¢ueo§o§o DOD-OCOa-eosea. "I.“D.wfl-.-U.Q I O I Q q . 0 7 O O r- . . . 26. 27. _ 28. 29. 300 31. 32. 33. llectrical resistance measurements can‘be easily‘ taken during the sun-er months. Note the sack red as insulation for the portable soil noisture bridge................................................ Ohm resistance at the 6 inch depth at 6o'r........... 0h- resistance at the 18 inch depth at 66°F.......... (In resistance at the 36 inch depth at 60;F.......... Field calibration curve for Grayling send, gravelly phase, at the 6 inch depth............................ Iield oalibretion.curve for Grayling sand, gravelly phase, at the 18 inch depth........................... Field calibration curve for Grayling'sand, gravelly phase, at the 36 inch depth........................... Soil temperatures in the red pine plots and in the open field............................................ Oululative radial growth curves for 1953.............. Crom-dineter graph med to plot cram menum... Subplot 804. subplot 80-8.......................................... S‘bplot 8040.00.00.0000000000000000000000000000000000 subplot m400000OOOOOOCOCOOOOOOOOOO0.00.000.00.00... Subplflb 120-3....ooo..o.............................ee S‘lbplw 120£eeeeeee0000000000000e0.000000000000000... PIE 7h 76 77 80 81 ‘82 8h 88 119 120 121 122 123 12h 125 ,. ‘r' «r- .0000. .0...- 0 o u I e a o e - e O O O O a O O a O DIOOCOIIUOQQ§OO~.~.~QQO10¢ coo-ooeeaoevov « . \ ‘ . ‘ a c D . v9 . . . O f f' r I O O O I C O O Q 'I c \ a O O I I O o o O 1 ‘ r I I ‘9 ‘ Q o I . D p , n \ n ‘ \ A ' \ OOOIOIOOOOoe-ve' . . Q0100IJOOQOQ-n \_ ' I Q0.‘Oq0o¢.c0.. .qIUU'OIAO. Lr 152. to. subplot ”Oieoeeeeoeeeooooeeeeee00.000000000000000... 3&1)le 1Meeee eeeeeee eeeoeee00.00000000000000000000 Snbpldb 1m£eeeeeeeeeeeeeeeeeoeeeeeeee eeeee .ooeoogggo PACE 126 128 a... VI!“ :5 e a n c . ‘ I I ‘ INI‘RODUCI' ION A fact well known to foresters is that by thinning a demo stain! of tilber the yield expected from the stand will not be in- creased. Increased growth rates for the remaining trees contained in the stand nerely indicate that the nutrient supply from the area has bean available in greater amounts for the growth needs of the reasiniag trees. For any set period of tine, the soil of an area can supply only a limited anount of nutrients for plant growth. The supply available varies with tile and depends upon the highly couplets and interrelated cheaical, physical, and biological factors which are in a state of perpetual activity in the soil. Thinning a dense stand of tinber results in a redistribution of the nutrient supply so that ' the total available quantity is shared with fewer individuals; con- sequently, the re-ining individuals show an increase in grovth. m- th. stand the yield mine th. sale, but it econ-e on fever trees. hay advantages are gained when stands are properly thinned. Sole advantages are: (1) Growth occurs on fewer st.; (2) the rotation can be shortened; (3) higher quality trees can be green; (h) eon. soil eoedition. night he ilproved end result in an increased nutrient supply; (5) fewer stem per acre with increased die-stars can result in a reduction of logging costs; (6) insect dang. can be reduced; and (7) healthier, stronger trees will result in ilproved stand condition. ‘ 2 Forest research conducted in a thinned red pine plantation grating on Grayling earl! on the Huron National Forest in Michigan has revealed that the greater the spacing betweai trees on a 35-year- old red pine plantation the greater the height growth (Balaton, 1953). The reason behini the increase in height growth after thinning was not specifically know. The water table underlying the area occurs at such a depth that not even overlying water froa the capillary runs. is available rot- tree yowth. Sine. drainage ie'eo rapid through Grayling sand and it was knows: that the general soil noisture content of the soil decreased to critically low levels, it ins thongit that perhaps thinning dense stands of red pine produced an increase in the aoisture content of the soil for those etanis which were thinned. Consequently, this study was devised to deter-in whether or not thinning a dense stand,planted 515, of Midyear-old red pine to various levels of basal area would podue a difference in the moisture content of the soil between the variou stews. Concurrently, research would be conducted with nylon electrical resistance units to detenine if they are adaptable for me in Grqling sand for the purpose of detersining soil noisture coalitions in the various stands. Additional mum's-em would be taken to detersine cululative seekly rainfall, weekly radial growth, and soil taped-stares. {jylrl r Y.‘ 3 Il'he study was conducted in a red pine plantation growing on Graylinx sand, gravelly mace, on the Higgins Lake State Forest in Michigan. The plantation had been thinned so as to produce stands of varying densities. The stands selected for the stldy contained basal was of 190, 120, and 80 square feet per acre, respectively. Additional neasurenents were taken froa an adjacent open field. SOME INFLUENCE ON SOIL MOISTURE The soil is dependent on its water supply for many of the characteristics found within the realm of its biological, chemical, and physical properties. Soil water, in addition to influencing the development of the particular soil in which it occurs, is directly responsible fm‘ supplying the needs of the vegetative cover grouting on, that soil. Trees will not grow except in the presence of at least a minimum quantity of water, depending upon the species; and, next to temperature, no factor plays so important a role in determining the distribition of tree species over the land surface of the earth (Raber 1937). The soil water with its accumulated nutrients is directly re- sponsible for Supplying the needs of existing vegetation. It functions as a link between the vegetation and the soil thich, -if broken, would have disastrous effects on the vegetation. Soils rich in nutrients could not support plant life without the necessary soil water. Soil water when available in adequate quantities can serve as a major supporter of vegetative growth on even the poorest of soils. The soil water supply functions as life-giving blood in the role of its support of vegetation. Wherever man concerns himself with growing plants, his attention must sooner or later focus itself upon the soil water supply. In new instances, maintaining an adequate supply of soil moisture for his crops becomes a matter of major concern to him. The water of the earth can be divided into three parts -- atmospheric water, water resting on the surface of the solid part. of the earth, and water thich occurs below the surface of the earth. ,— r u | . n ‘ . . . K - ., 1 n n A D . \ ‘ o , - l . ‘4 'r\| . , “ v " ‘ l o ' ' ‘ l I . ‘. . n I I I“ . 7 \ l I . y I o ' ‘ u (L , ‘ .1 n. i _ e I ( (’V ' o A « P \ ‘1 . . . I r I 1 . A ‘ ' . . y ' ‘ . . . . I ' , l , I .0 . v I ,- F' x ‘- l' ' ' ‘ I ‘ . < 0" ‘o f ' . t, . . " r a 3 " Ifl ‘ _ ' VA. . "J ' " ' . ' or . . -‘ ‘ ' l o I ' Y - (K 3 .v , F0 ' . U l . 1 1 ' ‘ . .. - - I . '7 r. S The water occurring below the surface of the earth can be further sub- divided into water existing above the zone of saturation, water in the zone of saturation, and water in the interior of the earth (Meinzer, 1923). This study concerns itself with water which is below the surface of the earth, but above the zone of saturation and within the reach of plants. Specifically, it is a stuck,r of the moisture supply present in a sand soil. at chosen depths. The dominant vegetative cover is red pine. This soil receives additional water from two principal sources -- ‘ rainfall and snow. Sleet, hail, and fog are relatively insignificant in being able to furnish additional water to the soil moisture supply. A characteristic common to all soils is that they contain pores of varying size and configuration. In sand soils these pores may con- sist largely of the interstices between the solid soil grains, or they may consist of the spaces between and within aggregates of soil par- ticles. Relatively large pores existing as passageways of soil animals, or brought about by the decay of roots, are rather common in forest soils and have an important effect on the soil-water relation- ship. The pores form an exceedingly complex system which is normally occupied Jointly by air ard water (Lutz and Chandler, 19146). The large pore spaces of a sand contain considerable water and, as the soil dries out, this water will be the first to disappear. Since the large capillary tubes form a relatively large part of the pore space available for water, they will hold a considerable per- centage of the water when the soil is saturated. In sands, large single intergranular spaces exist because of the relatively large n —1- n fl D‘ ,— P \ . - ’— J _ a v r ‘ 1 ' . . . r ' . IV’ ‘- ' r. “A n ‘_l l firs 6 size of the soil particles. The withdrawal of water from the larger pore spaces will cause a large decrease in the moisture content of the soil. then the moisture content of the soil is about six percent, the critical point is reached and a change in soil volume begins (Cameron an! Gallagier, 1908). Water is retained in the soil by two forces: adhesion and co- hesion. Adhesion involved the attractive force of molecules in the surface of the soil particles for water molecules. Cohesion is the force attracting water molecules to other water molecules. Through the action of adhesive forces tightly held films of water are built up on the surfaces of the soil particles. As more water molecules are attracted by the forces of cohesion, these film increase in thickness and finally fill the capillary pores unless entrapped air prevents them. The attractive force of the water molecules for each other is very apparent at the liquid-air interfaces; this phenomenon is referred to as surface tension (Lutz and Chandler,l9h6). Briggs (1897) recognized three form of soil water. Hygro- scopic water is that portion of the soil water which is retained as a thin film by the soil particles after capillary water has been re- moved. Neither gravitational nor surface tension forces can move it. Another form of soil water is capillary water. It is that portion of the soil water retained around the soil particles and in the capillary pores after the gravitational water has moved out. The last form of soil water, and usually the first to pass out of a saturated soil, is gravitational water. The soil is incapable of retaining gravitational water under conditions of free drainage. Gravitational water is LJ . . 17 ‘. \ e r . 4 . O 7 ‘ . l . Y . . I . u . i I . . Q n. y . b ' \ 0 I y ’ ‘ 7W \ . l A Y - V I I‘ w - . _‘ y - v . \ . ,— -. . ' ' I ,’ I O v . . n ' ' c-Q I - \ , . ‘ v x - ,W\ _. .- I v. ‘ y ‘ y . .- v I ~ -. I ’ A g y 7 I .‘ a . - fl I d , . K . , r- ‘ P ' . ._ . \ ' ‘ l ’ - _ . C ‘_ - - -- . \ I ' . r .‘ . F" . I ' -. . l T ' I l ' I ‘ r .P - - v. ‘ I’ f f ‘ r a “' drained away under the influence of gravity. Capillary water is most important from an ecological standpoint because this is that part of the soil water which is most available to plant roots. In soils, such as sand, gravitational water is not very significant to plants because of its leaching effect on the soil nutrient supply and because it moves so rapidly through the soil that plants have little time to utilize it. Hygroscopic, water has no effect in sustaning plant life because plant roots are incapable of overcoming the forces which bind it to the soil. Parker (1922) made a study of various new classifications of soil moisture which had been preposed. He concluded that the old classification of dividing soil moisture into hygroscopic, capillary, and gravitational water was still best. Capillary water is also referred to as water held in retention storage. Water in retention storage is available for use by vegetation and for evaporation. Detention storage is a common term used for water which is only temporarily detained in its passage through the soil; the term corresponds to gavitational water (Lassen, Lull, and Frank, 1952). Water moves through the soil in either the liquid or the vapor form. The forces produced by gravity and capillary tension are re- sponsible for moving soil water in the liquid phase. In the vapor phase, movement of the soil water is brought about by differences in vapor pressure. Unequal tensions developed under different degees of curvature of the surface film of water over soil particles produces capillary movement. In sand soils the smce between the soil particles 0 ‘ 1 O . . ' ' e . . A u ' . . ‘ V " ‘ v D ’ fl . ~ ‘ » F‘ V ' I a I ' ‘ . ‘ U c I ‘ ' ' n u I ' D ' ‘ 7‘ . , r . . 1 V . . I ‘ ‘ 1 ~ ' , . , w . I \ ‘ ‘ i . ~ 9 . I. . l- I - x O , I . . i v F O 1 .i n ’ . 1 ' . 8 is too large and the cohesive forces of the water molecules will be insufficient to raise the water to any appreciable height. Soils con— taining appreciable quantities of soil moisture have a relative humidity of about 100 percent. The pressure of the water vapor in the soil atmosphere increases with temperature. If there is a considerable difference in the temperature of the soil at different depths, water vapor may move from a warm layer of soil to the colder depths where it will condense as moisture (Miller and Turk, 19143). Lateral movements of ground water under‘the influence of gravity are slow. Movement on slopes is greater than in flat areas. Ground water can move very rapidly through gravel ani sands (Hubbert,l9h0). Capillary movements from a moist to a dry soil are too slow to be beneficial to plants (Veihmeyer and Hendrickson, 1927). If plants are to utilize the moisture in a soil mass they must extend their roots into that soil. Capillary movement from the zone of saturation to the capillary fringe is fairly rapid. Other terns used when dealing with soil moisture are: (1) hygroscopic coefficient; (2) moisture equivalent; (3) wilting coefficient; (’4) field capacity; and (5) sticky point. All of these terms represent constants or equilibrium points. The hygroscopic coefficient is supposed to mark the upper limit of the hygroscopic moisture range (approximately pF h.5). The method employed in detemining this value has been to expose a thin layer of dry soil to an atmosphere saturated with water vapor for a period of 2).; hours (Lutz and Chandler, l9h6). '— , ,o. ‘ ,.“‘ . .- r I. I \ o ‘ 4 . - o . I r \ I, . ’ \ v I w . o _ u a " ‘. . rm, ' l t O -‘ n F. I \ , r . ’ . ex ‘. . . . . f _. a, .. . . O r -1 . . ._ , . -' ,w. I . . ‘ -\ 7 . . . . i- . . . - A l r a 1 r. r If ’4‘ . . ,. , . . .. . ‘ i 7—. \. ‘ . . _ c- . ". V - ~-‘\ § . V _ - ‘a . V I . I O . — \ . f \. , . . . r » . \ ' . . ~- ‘ .l I - ~ \. r . . I . 9 The term moisture equivalent has been used to designate the percentage of water retained by a soil, when subjected to a constant centrifugal force equal to 1,000 times gravity (Briggs and Shantz, 1912). Bouyoucos (1929) introduced a method utilizing a vacuum pressure force for determining the moisture equivalent. The wilting coefficient of a soil is the moisture content of the soil (expressed as a percentage of the oven-dry weight) at the time when the leaves of the plant growing in that soil first undergo. a permanent reduction in their moisture content as the result of a deficiency in the soil-moisture supply. By permanent reduction is meant a condition from which the leaves can not recover in an approxi- mately saturated atmosphere without the addition of water to the soil (Briggs and Shantz, 1912). . The non-available water in a soil is the soil moisture content when in equilibrium with the moisture of the air. It is important to recognize that the moisture in a soil is not non-available until it has been reduced, to the moisture content of air-dry soil (Briggs and Shantz, 1912). The field capacity of a soil indicates the amount of water held in a soil after excess gravitational water has drained away and after the rate of downward movement of water has mterially decreased (Viehmeyer and Herdrickson, 1931). The first investigations of the sticky point were made by Keen and Coutts (1928). The sticky point is the moisture content at thich the attractive power of the soil for water is satisfied (Baver, 19118). 10 Rainfall, snowfall, or any other form of precipitation must first enter into the soil before it can add to the moisture content of the soil. The litter layer of the forest floor is important in that it tends to keep frozen soil loose, porous, and permeable men bare soil becomes solid and impermeable (Kittredge, l9h8). The organic material comprising the litter layer can absorb several times its own weight of water and quite often precipitation must first satisfy this big) absorbent capacity before it can infiltrate into the soil. The infiltration capacity of a forest soil is usually decreased as a result 'of excessive grazing and repeated burning. Sand soils, due to their single grain structure, are less affected by such occurrences than heavy-textured soils. Arend (19112) found that annual burning reduced infiltration an average of 38 percent in comparison with that in soils protected for approximatelyS-6 years. Non-capillary pores facilitate the avenues of free water movement in the soil; in short, they are responsible for conducting subsurface and base flow to streams. The effects of plant cover conditions ani treatment on these pores determines to a large extent how water moves to the stream. Water movement in the soil can be separated into two rather independent processes. The first of these -- infiltration - refers to the entry of water into the surface half inch of soil. The other process is percolation and it refers to the rate of flow at any lower level. The maximum rate at thiCh water can enter the soil surface is defined as the infiltration capacity of the soil. The rate at thich water can flow througl the subsurface layer is the percolation capacity of the soil. The usability of storage Q . I e. D u I ,1 . r. - . . 5 . - . , . i r .. . \ - A V .- , , . ‘ . a q , . . r . ’N ' . . . - . .- r r' . V V . q |‘ 7 - . . —. a ,a‘ -, , . v I - . ‘ . .. - . ‘ - A s r . a I I" \ v f" o o n .— .\ J 11 space in a soil depends on infiltration and percolation values in relation to rainfall intensities (Lassen, Lull, and Frank, 1952). Much of the water which enters a forest soil is moved downward by gravitational force ani thougl it eventually contributes to sub- surface and base flow, it is usually of no value to the vegetation on the area on which it fell. In addition to the loss due to gravitational forces, some soil water is lost by evaporation. Accord- ing to Lutz and Chandler (l9h6), the most noteworthy factors which influence loss of soil water by evaporation are: (l) the moisture content of the atmosphere; (2) wind velocity; (3) soil cover, both living and non-living; and (h) the nature of the soil, including moisture content and temperature. MEASUREMENTS OF SOIL MOISTURE g3 SITU There has long been a necessity for developing some technique whereby the soil moisture changes in a soil could be measured in situ. Scientists have long reco glized the fact that there is an increase in the electrical resistance offered to the passage of an electric current through the soil as the soil becomes drier. This knowledge led to the development of an electrical method for determining the moisture content of arable soils (Whitney, Gardner, Briggs, 1897); they wrote the following descriptions: For the measurement of the electrical resistance of the soil the Wheatstone bridge method is used with the alternating current and a telephone to indicate when a balance has been obtained. For the measurement of re- sistances in the field it is necessary to have an instru- ment sufficiently accurate and yet with a very wide range. . lilllllvllll 12. The bridge consists of a rheostat, comparison soils, induction coil, and a watch receiver telephone with suitable electrical connections. One arm of the bridge contains a 1,000-ohm comparison coil, a second arm con- tains a 900-ohm coil, and a lOO-ohm coil connected in series, while the third arm contains the rheostat. The electrodes finally adopted for field work consist of carbon plates each three inches long, three-eights of an inch wide, and three- sixteenths of an inch thick. Each electrode is cepper plated on one end, and an insulated No. 20 copper wire soldered to the planting of a length sufficient to reach above the surface of the ground to the measuring instrument. Recently a conparison of four types of electrical resistance instruments developed in recent years was made by Palpant and Lull (1953). One of the instruments compared, the portable soil moisture bridge (Bouyoucos ard Mick, 19110), was used for taking the _i_p_ situ moisture measurements of this study. The nylon electrical resistance unit first described by Bouyoucos (19149) was the type of electrode selected. The most recent develOpment for the measuranent of soil moisture is a method which employs radioactive probes, the use of which permits soil moisture and density measurements (Carlton, Belcher, Cuykendall, and Sack, 1953). At the present time the size, cost, and stage of development of this equipment greatly restrict its “330 One obstacle which has presented itself in the use of electrical resistance methods for determining the moisture content of soils is the fact that for some soils suitable laboratory calibra- tion curves which will accurately reflect field conditions have not been developed (Reinhart, 1953). , - . . . . I ‘ t. . \ '7 s \ ' . , . l l f . \ v“ I r, .x r . ' \ . - I" \ r b 1 f. -- 3 \. ‘ V\ l ‘ v ( (I I. 13 To develop a suitable field calibration curve, Reinhart (1953) described a method used at the Vicksburg Infiltration Project, U. S. Fwest Service: Under the area concept the unit is installed in or adjacent to the area it is to represent -- at Vicksburg usually a plot 6 by 6 feet square. It is calibrated by drawing soil samples at random from this area and plotting the moisture content of the samples against the resistance determined at the time the samples are taken. The resistance is an index of average soil moisture at a particular soil depth over the entire sample plot. This is a distinct advantage, because the marked deviations in soil moisture that occur even within a small area give the value for a single point little significance. REVIEW OF LITERATURE Some Effects of Stand Density on Soil Moisture Ebermayer (1889) investigated the relative soil moisture quantities found during the course of a year under stands of pine, varying from 25-120 years in age, and in open fields. The soil samples were taken at depths ranging down to 80 centimeters. The moistln'e content of the soil was expressed as a percent of the oven- dry weight. His results show that the forested areas selected for his study contained considerably less soil moisture than the open areas for all four seasons of the year. Differences were greatest in late summer and early autumn- An investigation conducted in beech stands gave similar results. Some of the conclusions arrived at by Craib (1929) concerning soil moisture and its relative abundance in the Open and under forest cover after two years of investigation at Keene, New Hampshire, are :' 1. Both in the Open and in the forest there was considerably more moisture present during the growing season in the upper soil layers than in.the lower. The amount of soil moisture consistently decreased wdth increase in.depth, at least to 100 cm. 2. Both in the cpen and in the forest there was a rapid falling off in the amount of water present in the soil layers down to a depth of about J40 cm., below which there was much less change. 7. The soil became progressively drier in the forest with increase in depth, despite the fact that the tree roots were largely concentrated in the surface soil layers. Little moisture was lost by direct evaporation, due to the thick covering of needle litter. 8. The open soils contained considerably more moisture during dry periods than the forest soils. The difference was greatest in the upper soil layers and became progressively less with increase in depth. Albert (1915) conducted a study on stand density and its effect on the water content of the soil. The study was conducted at Eberswalde, Germany,in.three pine stands which were growing on a sand soil. Originally the 25-30 year old trees were all at the same degree of stockingw Two of the stands were thinned to equal densities of stocking. One of the two thinned stands had been cleared of all slash; in the other thinned stand the slash was left lying on the ground. The third, unthinned, stand was used as a control. The graphs for the years 1912 and 1913 show that the thinned stand on which the slash was left had a consistently higier soil water con- tent at both the 20 and 140 centimeter depths. The thinned stand which had the slash renoved contained less soil water for the two- year period than the stand in which the slash had been left. The unthinned stand contained the least amount of soil water fbr the two-Year period. There were periods when the differences were ~r\. »I I . O . n . . r\ ‘ . . . C r ,, Q. I 4 '\. .— ' ‘ I Q 0 1 . u \ ~ , — l u . . , N ,‘ . . \ . - n u a . r- r V— ‘ o 4 ‘ , ' l .r - -, A '\ . ’I ‘ a n A 15 large and other periods when the plots were at nearly the same moisture content. The moisture content of each plot was determined from 100-150 gram.soil samples collected at weekly intervals from the first week in May until the second week in September in 1912, and until the third week in October in 1913. The study showed that thinning a stand of pine on a sand soil does increase the moistmre content of the soil. The maximum moisture percentage (in terms of oven-dry weight) recorded at the 20 centimeter depth was 12.3 percent and the minimum.1.8 percent. At the ho centimeter depth the maximum and minimum amounts of soil mwisture were 8.1 percent and 1.6 percent respectively. In 1913 there was a general decline in soil moisture content from May to October. Albert (1925) also investigated various sand types, ranging from alluvial to dune sands, and of the various types of vegetation each would support. He concluded that further research on a larger scale was justified in order to learn how to best use the various sand types to produce hardwood in addition.to pine timber, and to build up the soil. Such a study might be justified for a system of intensive forest management, or for the purpose of increasing our knowledge of the potential capabilities the various sand soil types of Michigan possess. Eventually'better ways of utilizing our sand soils might evolve from such a study. . l r ‘1 r-. n . ’ I n O x r . i / r Q r ’< ‘ I . "\ . , . . r DESCRIPTION OF THE AREA The red pine plantation selected for this study is located in Crawford County, Michigan, approximately one mile north of Higgins Lake and one quarter mile east of U. S. Highway 27. The plantation is knom as the Bosom Field Plantation ani is in the Higgins Lake State Forest. This part of the county is characterized by several separate ridges, irregular in outline, but having an east-west trend. In general, the relief is gently rolling or moderately hilly. South of the plantation area a very prominent ridge separates the Higgins Lake plain from the outwash plain on thich the plantation is located. Approximately half of the county isrcovered by dry sand plains. The maximum and minimum elevations fbr the county are 1,h80 and 1,006 feet respectively. Climate The main climatic features of Crawford County are: an annual average of 30 inches of precipitation, this includes the melted snow?- fall; an annual average of 78 inches of snow; a mean annual temperatm‘e of about h2‘F., short mild summers, fairly high humidity, a large number of cloudy days, a small percentage of possible sunshine, and a low evaporation of moisture (Veatch, 1927). According to ”Climate and Man" (19M), weather records maintained for to years show that the mean annual growing season is 115 days long. The last killing frost in the spring 81d the first killing frost in Kn. —\ i x . _| . V (I .\ .. w. \- fill» r” .14 A a I . ,. . e . P .w r]... x r J ., fl. 1 J r - w I ., .J V o.‘ I r? o .I i, a r . O 1 I O f ’\ h ’\ l7 \. . . t u\ 4 ,.H.. .. ..m zhiowflfim Wirui ‘ ).\ll.) «.0: Aerial motogreph showing location of the red pine plantation. Figure 1. 18 the fall, expressed as average dates, occur on May 27 and September 19 respectively. The maximum and minimum temperatures recorded were 106 and -h1‘F., respectively. The precipitation is well distributed throughout the year; the rainfall may occur as prolonged rains or as fraquent showers. Agricultural History According to Veatch (1927): The history of the settlement of the county and of the agriculture are closely connected with lumbering, which began on a large scale in the decade 1870-1880. The first land to be logged over was that covered by pine forests, and most of these trees were removed by 1890. The lmrber- ing of hardwoods and swamp timber followed but was of less importance because of the comparatively small areas. The farming population did not increase so rapidly as in counties which had a greater proportion of hardwood timber. The early population, excluding trappers, came primarily to operate the logging camps and lumber mills, and only a small amount of farming was carried on. The census of 1880 and 1890 show, respectively, 175 and 202 farm in the county, but the amount of land actually in cultivation probably did not exceed 3,000 acres. A small income was realized by the farmers through supplying the camps and 1111113 with necessary agricultural products, particularly hay and other feed for work animals. it the same time the farmer could work in the logging camps in the winter and thus add to his income. Probably the greater number of the earlier established farm have been abandoned, particularly those on sandy lands. The past history of the Bosom Field Plantation closely compares with the above description. Originally the area was under forest cover. The former owners cut off the timber and attempted farming. . The poor quality of the logged off land soon made fanning unprofitable am the farm was abandoned. The abandoned land was acquired by the state and the plantation was established in 1912. 19 of stocking ‘ the 4.- Plot 190, showing (or 00;”: n the stand; wept. m fun a for m. a]: new .13. foe-en "m 2e Figure 3. Macrame mm tea-n ”angina; £1... Annual “Mummmnmm. 20 Figure )4. Plot 80 in Augmt, 1953. The openings were quickly invaded by passes. 21 Hm. 5e Vegetative cover on the open field consisted mostly of m1. grasses and sweet-fern. 22 23 Plot Description Three red pine plots were selected fcr this study. Each plot was desigmted with a number corresponding to the basal area which the stand contained. Plot 190 contained a basal area of approximately 190 square feet. This plot was unthinned and represented the original stocking of the stand as it was planted in 1912 with 3-0 stock. The trees were planted in horse-plowed furrows with a spacing of 5x5 feet. This spacing resulted in a stand of 1,710 trees per acre (Engle and Smith, 1952). In 1951 Plots 120 and 80 were thinned to basal areas of approxi- mately 120 and 80 square feet respectively. Plot 120 averaged 696 stems per acre and plot 80 averaged 603 stems per acre. Practically all of the trees in these two stands are rated as dominants or codominants. Plot 190 contains some intermediate and suppressed trees. Soil Description The entire area contained within the red pine plots consisted of Grayling sand, gravelly phase. This soil type is a rather common occurrence throughout Crawford County, and usually occurs between areas of Grayling sand and Ros elawn sand, gravelly phase. Roselawn sand occurs on low swells and on rather smooth rounded ridges and hills. Broad dry swales and valleys intervene. Grayling sand, gravelly phase, tends to occur at the base of the hills and ridges which have Roselawn sand, gravelly phase, as the principal soil type. Beyond the gravelly phase of Grayling sand are the relatively level \ . . r ,.\ ‘ I A \ \‘ r r n . . 1‘ ('3 1 J I a r» '. 7 7 I b \ A . n l ‘ ’- V" i 1‘ i / \J . - - - ~ - ' -¢ ' ' ‘ - \ \r s! 2h sand plains with Grayling sand occurring as the dominant soil type. A typical profile of Grayling sand, gravelly phase, has the following characteristics: The litter layer is approximately one inch thick and usually cms ists of dead conifer needles; the layer of fermentation is approximately one half to three fourth inch thick and, according to the Munsell color chart, is light gray in color, its pH is h; the A0 horizon is black and is approximtely one fourth to one half inch thick, it is strongly acid with a pH of b.53 the A2 horizon is a gray sand from two to eight inches thick, its pH is h; the 82 horizon of sand ranges from a strong brown to a reddish yellow in color, it has a pH of h, and is from 10 to 15 inches thick, at the approximate 18 inch depth, measured from the surface, there is a layer of gravel composed of angular, smooth, or rounded pieces of gravel which is made up of chert, granites, sandstones, and some calcareous rocks; the C horizon, or parent material, is a pale yellow usually large grained sand with a pH of 5. The trees obtain some nutrients from the gravelly layer because many of the stones examined had characteristic depressions etched over the entire surface, which were produced by the action of solvents surrounding the tiny rootlets found in the depression. According to Veatch (1927): Except for the higher proportion of gravel, which corsists of smooth or rounded fragments of many kinds of rock, the gravelly phase is similar througrout to typical Grayling sand. There is a suggestion of a little higher natural fertility in areas of the gravelly phase, indicated by a somewhat more thrifty tree growth, and owing, perhaps, to a higher proportion of minerals other than quartz in the parent materials or to a somevhat higher moisture holding capacity. ' I - r- . ' 7 7 . r- 7 _ l I e .‘ - ' 7 , . \ \ , 7 x . .. . . r . ' f . . n h. . '\ A ‘ I \ r . ' | _ '3 ('7 . \, ' ' ~ 0 I . x A» . 7 I' . e A t \ . I ' A I V ' ‘ V \ (A ' a \. ~ . 7 1 r~ . , . 7 l ,a‘ ‘ ‘ ‘\ ’ I \l ‘ A . . . r ,’ . 7 . ‘ . i I 7 7 C n/ ,1 It s ’7‘ . l I . . n .( . ‘ v . . a , 7 ' I n , . . ‘ r ‘ P \ n , . , I . I l l . ‘ h 7 . . 25 Referring to Graylingsand Veatch (1927) wrote: Grayling sand including its gravelly phase is the most extensive soil in Crawford County, occurring in large uniform bodies in the eastern, central, ard southern parts. Areas of this soil are level, plainlike, or very slightly uneven, owing to shallow dry depressions and hummocks of wind-blow sand. The land is excessively drained and dry, owing to the perviousness of the soil and the underlying geologic formation. The water table or permanently wet sand probably lies at a depth of more than 15 feet. The original tree growth probably consisted mainly of jack pine and red pine; there were probably a few white pine, scarlet oak, ohite oak, and the jack or northern pin oak. The present growth consists mainly of jack pine, either in thickets or scattered in association with small oaks, ard a scrubby growth of aspen. In the more open areas the characteristic and more common shrubs and herbs are blue- berries, lcw willow, sweetfern, bracken, a sedge, a species of bluegrass, oatgrass, ard bunch grass. The pasturage value of the land is low. The most logical use of the greater part of the land at present seem to be for forestry and recreational pur- poses, at least until some more economic use for it is discovered. In places the jack pines are of sufficient size and density to have some value, arr! wild blueberries produce profitable yields. . . x . . nu 7 e . 7 . . . o . . A i a. . , . . n _ . y N x i u i .. . l . o. n . . A . l\ , . . 7 , , . a i -\ cc 7 . . I V a\ . n ( x . c . r J r A N . f . ox . N \1 ”\l' 25 Referring to Graylingsand Veatch (1927) wrote: Grayling sand including its gravelly phase is the most extensive soil in Crawford County, occurring in large uniform bodies in the eastern, central, ard southern parts. Areas of this soil are level, plainlike, or very slightly uneven, owing to shallow dry depressions and hummocks of wind-blown sand. The land is excessively drained and dry, owing to the perviousness of the soil and the underlying geologic formation. The water table or permanently wet sand probably lies at a depth of more than 15 feet. The original tree growth probably consisted mainly of jack pine and red pine; there were probably a few white pine, scarlet oak, mite oak, and the jack or northern pin oak. The present growth consists mainly of jack pine, either in thickets or scattered in association with small oaks, am! a scrubby growth of aspen. In the more open areas the characteristic and more common shrubs and herbs are blue- berries, low willow, sweetfern, bracken, a sedge, a species of bluegrass, oatgrass, ani bunch grass. The pasturage value of the land is low. The most logical use of the greater part of the land at present scene to be for forestry and recreational pur- poses, at least until some more economic use for it is discovered. In places the jack pines are of sufficient size and derm ity to have some value, and wild blueberries produce profitable yields. 1 'K ’ l . . (\ e . r' e . 7 , f‘ ‘ F ‘\ . A . .— —— I . 1 y . . ,-‘ ' l I‘ f‘ x ._ I 7 [’W . W‘ I I l \ r ( 3 METHODS OF PROCEDURE Installing the Nylon Electrical Resistance Units On November 8 and 9, 1952, the nylon electrical resistance units were installed. The initial mrk consisted of establishing the plot centers fcr the purpose of being able to locate the buried units whenever measurements would be taken. . It was then necessary to determine the depths to which the units would be buried. A. nearby red pine was selected which approximated the dominant plantation trees in size, then a trench was dug two feet away from the tree to a depth of five feet. The riser roots and 2-1/2 inch lateral roots were concentrated at the six inch depth. Smaller lateral roots approximately one half to one inch in diameter/xfihe 18 inch depth and sinker roots were found descending to the 36 inch depth. At the same time the soil profile was examined in detail and the appropriate notes taken for purposes of later describing the soil profile. A pH kit, yardstick, and a Munsell color chart proved valuable for this work. The locations of the unit installations were chosen at random througrout the plots. Each installation was carefully mapped, using the center stake at each plot center as a reference point from which to determine the azimuth and distance to each unit stack. Then a diagram was made showing the direction and distance from each tree, designated by d.b.h., surrourding the unit stack to the stack. For the actual unit installation, a large piece of heavy cardboard, a yardstick, a flashlight, a two-inch barrel auger (hollow _ I \ . I . e I A v\ r? . _ \ 7 i a c G, v C r _ u r‘ N r , U a . 7 . . c — . - ‘ . \ 1 e l f) f .\l" 27 cylinder type with two projecting cutting edges), and three nylon units were used. As the auger boring was progressively deepened the soil was carefully laid out,in the sequence with which it was rencved,on the heavy cardboard. The soil was very dry and seemed as dry as the soil collected on August 29, 1953, 10 months later. The flashlight was very useful in placing the block properly at the 36 and 18 inch depths. The two-inch barrel auger was selected because it minimized disturbance of the 5011., Occasionally, in very dry sand, it is necessary to tamp the soil in the auger cylinder from above with a suitable rod before the soil out“: be lifted from the boring. If this is not done the send will fall out of the bottom of the cylinder as the auger is being extracted. The nylon units were installed dry because it was thought that doing so would better permit their stabilization at the depth to which they were buried. If readings are taken from the units during the winter, when a deep snow cover is probable, it is necessary to map the, location of the stacks very carefully. To prevent freezing of the wires, which lead to the buried electrodes, to the duff, or to crusted bottom layers of a snow mantle from which they can be removed only with great difficulty, it is necessary to suspend them above the location from perhaps a stiff upright wire placed in the ground. A straightened wire clothes hanger would probably prove satisfactory. If very permanent installations are to be used and vandalism is not expected, then permanent switch shelters as. described by Palpant, Thames, and Helmers (1953) may be built. In taking the resistance readings with the portable soil moisture bridge, it was found necessary to insulate the bridge from the ground. A dry ‘ _ W I W — ”x . P _ (I. _‘ e ' ' - r. J "i' _ 4 .7- -‘. ; I \ 4 ’\ A p . V v -r\ I I r r . \ J b. 1' ' "\ n- ‘r \ ’\ r r. . . . I ’3 I\ v "f , t 7 '\ 7 “a ' r l \ WI " e I 0 . (. -r-wq .(‘ r' iiiii— n Fig”. 6e Field equipment med during the installation of the nylon electrical resistance units. 28 '11.! Ill: Figure 7e Slit trench dug to determine depth of root concentrations . 29 Iliad-I {Iii-ll!“ r ....I|.\: 30 Hm. 8e Installing the nylon unite neceeaitated the use of a piece of cardboard to keep the eoil in the order in which it Illa renoved . Fig”. 9e Taking nylon electrical reeiatance unit reading under frigid winter conditions. February 28. 1953. 31 32 potato sack proved satisfactory as it was carried without difficulty. Collecting Soil Samples When a Deep Snow Mantle is Present The soil cans used during this study were numbered both onthe lid and on the side of the can proper. This is necessary because each can nmst be accurately identified during the course of the weighings. The soil samples collected weighed approximately 685 grams. The cans, each of which must be independently weighed, averaged approximately 85 grams. The oven-dry weight of each soil sample was about 600 gram. In working with sands, large samples are-necessary, especially when the soil moisture content is law. For collecting soil samples a three-inch barrel auger is to be preferred to a two-inch auger. Samples can be collected very quickly, especially if the sand'soil is above four percent moisture content, and no large pieces of gravel are encountered. A rather moist sand extracts readily from an auger boring, but relatively dry sands can only be extracted after tamping. A very important advantage in using the three-inch barrel auger is that the boring is large enough to permit rechfng dom into it to remove any stones which may be hindering the penetration of the barrel auger cylinder. The handle of the barrel auger should be marked so that one only needs to bore down to the mark indicated to collect a sample from the depth desired. Care must be taken so that when the cylinder is at the indicated depth the sample will be so centered in the cylinder. Allowance must be made at the tap of the cylinder to permit removal of any soil from an upper level which may have fallen to the bottom of the boring as the barrel auger lllllvld!t .ll .IIIDII‘I. \ I l 1 . . . I. a .. a . _ j ,, . . _ mt .. .. \ O . . a r; . r .. w a, , _ . . . . _ ‘ | in u a \I l‘ u . I . a l . _ n . . . u l _‘ A. P _ m ._ . O .. ‘ . r r. . t v . . . fl _ v r l n '1, — i. . . o a r- o i. c m n O F . m » r1 . 7 y . . . H a ., a . ‘ A A I u n . h \ fl . v i - a 4 . n r1 n. -3. . fl A s .. _ , . r!” . . ... ..n Fl». I.’ r ,I r, a r. . 33 is reinserted subsequent to removing a cylinder full of soil. If these precautions are followed, samples which are representative of the depth sampled can be accurately and easily collected. The soil cans must be sealed immediately and the plot designation and depth sampled must be marked on the sealing tape. "Scotch” brand" masking tape No. 202 worked very satisfactorily at air temperatures above approximately 32°F. At the lower temperatures it should be carried in an inner pocket to facilitate its adhering to the soil cans. At the lower temperatures it tends to become brittle; hence, it must be protected by keeping it warm. It provides good Irotection as a moisture seal. If samples are collected on very warm, muggy days from a deep soil level, pronounced moisture condensation will occur on the outside of the can. The samples must be quickly sealed after extracting them from the soil. To do this, a soil collecting crew of two peeple is a necessity; in fact, if many samples are to be collected, it is necessary to have a permanent crew of two so that the samples may be collected efficiently. During this study six samples were collected from each plot at each deptmwee'i‘crgs necessitated using a crew of two. If soil sampr are collected when a heavy cover of snow is on the ground, the use of snowshoes is a necessity. It is. extremely difficult to walk any great distance without them. On February 28 it was necessary to collect soil samples,w:'Lth snowshoes being used to provide mobility. on this occasion it was learned that a ruck sack, or;potato sack, is extremely desirable for carrying the soil cans because ofth'oirlight weight and ease of carrying. Two sacks are very useful to carry the full soil cans. Speed is essential when working "\ . 4 , . .( I u C . . O . P . 9 i O r J. , up . l _ ._ - _ »r . r ,A . r . t u \ _. _ l. r a \ . .i . r J . , _,‘ e. _ _ v i . I . . . r a. n . n - . a . N. r W x a 1“ P. 3h under frigid conditions and one should not have to waste time handling a sack full of mixed full and empty cans to secure an empty can. A shovel is an absolute necessity for clearing away the snow at the locations at which the samples are to be collected. On arriving at the selected location the man who is to turn the auger removes his snowshoes and with the shovel clears an area large enough to collect the sample without having snow fall into the boring. The shovel is then placed upright into the soil at a sufficient distance from the boring to permit an accumulation of discarded soil without danger of it falling back into the boring. The man who is to seal the cans should stand to the left-front of the auger man, facing him, so that the sample may be readily placed into the soil can with efficiency. The man handling the cans should trample down a small area so that by tapping his snowshoes together the webbing presents a clean surface upon which the opened cans may be placed upside down to prevent snow flakes, or falling snow from the crmms, from adulterating the sample. Cans are sealed and marked immediately on the masking tape as soon as the sample is collected. The can number is only used to identify the can after the seal is removed. All the cans should be Opened at once as this is an important time-saving Irocedure when working under frigid conditions. The sack containing the full soil cans can be readily carried slung over one shoulder. If the terrain is such that freedom of both hands is a necessity, then an aluminum frame mountain-type rucksack is best, because of the ease with which heavy loads may be carried and its large capacity. C . r . , ' 7 r J A ,— .. A " z I . _ _ K _' . ' Ark 7 r g . . . P . , . C . _ . . r _ . , ,. , _ - r s ‘ s ‘ ,l , s - ' I ' . 0 ’ v 7 . «q‘ s “ ' — ‘ .I a .. . I a — i M" ~ , ,- , . { A q . ‘ q .‘ . s , ' I - . , I I ' . .-, A ,.. O a _ g _ , ,. r _ . i . ’ , ‘ « r . u “‘ r r J v 0 . . - -r". r o I ' ' ‘ , A r‘ . .' . ' r“ ,. 1'“ ~ 1 “ a; > . 4 _, » v . _- n i ‘l " .— - ,‘ . . f w . _,‘ ' — . O . o I i . ‘ ' " x ' ' - '\ u '. " _ _ I . . ' r ' V r- fi-.‘ x - I A r ‘ I f V ‘ ' , . a o p A ’ r ‘ P fl ’- V v ‘r ' . ‘ .. ‘ I ' . ,H g. . v Pp ,‘ .I’ Iqr , 1" rr‘ ,“ ,J / ~P 1 ‘ ' a \ 7"— (A rat, e .' p n v H!" N I » u I i r . a- t s .\ .- I . l _ ,., 35 In the laboratory the samples should always be systematically grouped by plots and then stratified by depth to facilitate recording the can numbers and to avoid confls ion. Mimeographed forms are very should be used useful, and/wherever possible if determinations of soil moisture content are to be carried on for a long period of time. They are fine time- savers and their use should be stressed. Field forms should be mimeo- graphed too; they are especially useful for recording resistance temperature and dendrometer measurements when a set procedure is followed week after week. The laboratory technique consists of weighing the samples after the tape is removed; oven drying them at llO‘C. until a constant weight is reached. They can be pemitted to cool in the oven and then they are/:ighed. The loss in weight represents the moisture previously contained in the sample. I The can weight must be subtracted from the dried samples plus can weight so that the oven-dry weight of the soil can be determined. The moisture content is divided by the oven-dry weight of the soil md the result multiplied by 100 to arrive at the moisture percent in terms of oven-dry weight. The computations are tedious and require considerable time. A calculator is a very useful tool in performing the type of computations required. All the electrical resistances recorded have to be standardized to some chosen temperature. The standard temperature chosen for this study was 60°F. Figure 7A in the publication by Bouyoucos and Mick (191m) was used to standardize the ohms resistances recorded in the field e 7‘ . \ ~ \ I I I I I I I . f- I IIIQI \ [I ; N . , . I r "- A , . b I . A . . k - I I I G I I I I . . F I 4 . . i A . . " x. ‘ l -- . . I ,—-\ r V ‘ I I I I I I _ . . h . ,‘ v . ‘ f“ ' 1“ ' ‘ [I i (' J ‘ l ,. \4 . a; _, " ’r " ' — ‘ -. I . \ ' ‘ ' I . u - ' I . v ’ \ .. x ’ r H r“ 7 . v ‘ ‘ I" ' I ) - h . ' j r r If I II . III ‘ '.- s A . ~ . r"\ r r \ I I , I— II I I I I . . '- e I I I I I N _ . I a \. . . . I ‘ I h . q . . " ,’ ‘, . D ’ ' . ' _ - A I . '. I Al -~ -A I ‘ . I I I I I I . - I . II I I I I III Ir I ~- . F t I ,. x . s A] I - V‘ 4 . I I I I I I . . . .. r- ~ . . -\ ' . ‘ ~ - f‘ R q - Q I I I - _ . . v ' I .- - v o . . ’\ 'x - r ' - r h 7‘ I ' ‘ A - . I- . — ‘ » 7“ ‘ I I I ' ' . . . a. '1 .. r . h 7‘. a v C “ I I. \ I I - I . . . x I r I '\ l‘ I . I . ~ f . n ’ V . h _ . i ' . -. . ’\ . ‘ 7 I r A" . . I V - I ' ~ - ‘ .*\ . - \ -7 A r< Ifi . In ‘ ~-- '\' . ‘V ' n ~ a ‘4 I r . y 4 - ‘ . I . i ‘ I 4‘ ‘ ~ \ " ‘ (5," F t h‘ — . A . J A. \ 4 v Figure 10. Collecting soil samples from Plot 80 in July. 37 The soil temperatures were taken with tm soil thermometers being used As a check on the recorded temperatures. A standard rain gauge was used in an adjacent open field to record accumulated rainfall. It was placed in a pit so that the cool soil would minimize evaporation. Dendrometer Installations To efficiently put in dendrometer irstallations, two men are required. For equipment they need a brace and bit, or a drill and bit, round-headed brass screws 1-1/2 inches long (for red pine), two screw drivers, and a metal template. The metal template permits placing all the wood screws in an even pattern and thus saves time. Drilling a small hole into tre tree prior to driving the screws into the wood considerably reduces compressive fcrces and still gives a secure base. For greatest efficiency, one man should hold the template at the desired location while the other drills the holes. After all holes are drilled, both men are free to drive the screws. Above each setting of three screw a small 1/2 by l/2 inch aluminum pressure plate was fastened to the bark by using ferrule cement. The pressure plate was placed so that the actuating rod on the dendrometer pressed on its center. With a relatively smooth barked species, such as red pine, a pressure plate of the type described is probably not necessary. The brass screws are driven into the wood onlyto the point were the dendrometer will record measuremnts somewhere within the first 0.100 of an inch; this permits ccnsiderable expansion of the bark before a readjustment r v n r _ , . . a p . , o . ‘ t o . u 7 ~ . , .\ . v I . _ , I . x ‘ , . _ A _, . , . 4 f . rI. .. . . _ . , r C , y o . . . . ; . . , . x v A O r r‘ . 1. J , v . . r. . ‘ x A ‘ , J r K , . n . A l.\ . 1,4 f pl. 1|.le n o I s Figure 11. Taking urns wit radial ‘ h a dial 90‘!th mt 1953 page (1’ ”a o m or. 38 39 of the screws is necessary, and is ample enough to record one season's radial growth. All the screws were placed 14-1/2 feet off the ground ard on the south side of the trees. Laboratozflal ibration Experiments To be able to convert resistance readings in ohms to a soil moisture percentage, expressed in terms of oven-dry weight, a calibration curve must be developed for the particular soil type being used. It was soon apparent that no such curve already developed would fit the field cmditions which existed at the red pine plantation. Consequently, it was decided to investigate some other approaches to the problem. It was first decided to increase the mass of sand involved ard to determine how drying proceeded within the container. 'A nuzrber 10 can was used and within it six nylon units were stratified at one inch intervals (Figure 12). The resulting data show that drying groceeded from the top, open end of the can down to the bottom. The sand in the can was saturated at the beginning of the experiment and at the end it was almost thoroughly dry. The data fcr the experiment are presented in Table VII. At the conclusion of the experiment, when the resistance readings from the top, upper surface of the can to the bottoms were 1,800,000, 1,h00,000, 22,500, 1,350, 575, and 525 ohm, the sand immediately surrounding each block was weigled, oven-dried, and weigled again. The weigiings were done with an analytical balame and the resulting moisture percentages in terms of oven-dry weight were from top to bottom - 0.0738, 0.1390, 0.5999, 1.5910, ("a f‘ 140 1.8170, and 1.795 Percent. Thus, for a range of from 525 to 1,800,000 ohms, the moisture percentage varied by only 1.7).; percent of oven-dry weigit. From Table VII it can be seen that the blocks were very slow to respord to changes in the moisture content of the can. A new approach was attempted to see if a more rapid response could be secured from the nylon units (Figure 13). A number 10 can was perforated at the bottom and placed on three legs so that drying could proceed from the top and bottom of the can simultaneously, and thus more closely simulate field conditions. The six units which had been stratified from the top to the bottom of the can responded immediately to moisture changes (See Table VIII). At the conclusion of the experiment the blocks from the top to the bottom of the can had the following resistance readings: 910000; hh,ooo; 7,200; 14,750; 30,500; and 780,000 ohms. The corresponding moisture per- centages determined by oven drying and using the analytical balance were: 0.2810; 1.0082; 1.h223; 1.3812; 1.2010; and 0.5h68 percent. Again, for a resistance range from h,750 to 910,000 ohms, the moisture percentage varied only 1.11113 percent. The last attempt at developing a laboratory calibration curve resulted in the data given in Table IX. Soil sample cans were per- forated and the nylon units inserted vertically in the center of the can so that drying of the sard would immediately register as a change in the resistance reading of the nylon unit (Figure 13). These represent the best results obtained, but still they do not approach field conditions. A field calibration curve seems to be the only proper approach. hl When saturated, the soil samples of Grayling sard, gravelly phase, had soil moisture contents of 25.3, 22.14, and 18.9 percent of oven-dry weight at the 6, 18, and 36 inch depths, respectively. Figure 12. Setup using miter 10 cans used in laboratory calibration of the wlon , unite. Cam had solid bottom. Figure 130 Setup showing the perforated number 10 can on supports, and the soil cans with perforated bottom med in the laboratory calibration experiments. REULTS The Soil Moisture and Snow Supply During Late Winter And Early Sging During the month of February, 1953, the total amount of rain arli snowfall recorded by the U. S. Weather Bureau's cooperative observer at Higgins Lake was 3.511 and 26.3 inches respectively. Even as early as February 28, the first day that soil samples were collected, it was evident that the existing snow cover and the rainfall, shich had fallen previously, were going to furnish a large share of the soil moisture for the weeks ahead. ‘ ' When the Bowoucos nylon units were interred during the first week of Novelter 1952', the soil moisture supply appeared very low. The sand grains would not adhere to each other even slightly. On February 28, however, a very different situation existed - the sand throughout the soil profile was very moist and on being moulded would retain its shape. The soil moisture supply, as determined from the soil samples, varied from h.6-8.6 percent of oven-dry weight. The moisture supply at the six inch depth terxied to be larger than that at the 18 and 36 inch depths. Plot 190 had more moisture than plots 80 and 120, $1121: were approximately at the same moisture level. The precipitation thich had fallen during the winter months had obviome been effective in restor- ing water to the soil. 8 In spite of the 23’F. air temperature prevailing at the plantation on February 28 , and the 21 inch snow depth, only the pine needle litter was frozen. The frozen litter condition probably resulted from a (l ’f F r; ' z r'- _' r" f" 1 " \ f - I - .. hS thaw period during which much crown drip combined with the water fr“ the melting snow to saturate the needle litter, or perhaps a period of precipitation in the form of rain follzwed by colder temperatures and snow. Possibly before the snow began to deepen appreciably low tempera- tures froze the saturated needle use into a sheath of solid ice above thich the snow began to accumulate. Below this sheath of ice-cemented needles, which averaged one inch in thickness, the soil in all the plots was moist; noehere was there any evidence of frozen soil. This was a good example of the insulating effect of needle litter and snow cover as protection against soil freezing. In an adjacent open field covered with grasses and low shrubs, the frozen sheath described as being present in the conifer plots was nowhere in evidence. In fact, the mat of dead gasses .was very moist. The soil as in the conifer plots was not frosen. In case of a sudden thaw the water formed by the melting of the snow cover could have readily infiltrated into the soil of those areas where the grass cover existed. There would have been comiderable runoff from the conifer plots because of the ice sheath. During the month of March, precipitation was again in the form of rain and snow. A total of 1.53 inches of rain and 10 inches of snow produced an increase in the soil moisture content of the three red pine plots. Plot 190 continued to have the highest soil moisture percentage at all levels, ranging from 9.8 percent at six inches to 7.5 percent at 36 inches. The most uniform rise occurred in plot 80 there all three depths showed an approximate increase of 1.5 percent. By March 26 . plot 120, which on February 28 had been below plot 80 in soil moisture m rr f‘. 1:5 thaw period during which much crown drip combined with the water from the nelting snow to saturate the needle litter, or perhaps a period of precipitation in the form of rain folhved by colder temperatures and snow. Possibly before the snow began to deepen appreciably low tempera- tures floss the saturated needle mass into a sheath of solid ice above which the snow began to accuumlate. Below this sheath of ice-cemented needles, which averaged one inch in thickness, the soil in all the plots was moist; nethere us there any evidence of frozen soil. This was a good example of the insulating effect of needle litter and snow cover as protection against soil meaning. In an adjacent open field covered with grasses and low shrubs, the frozen sheath described as being present in the conifer plots was nowhere in evidence. In fact, the mat of dead gasses .was very noist. The soil as in the conifer plots was not frozen. In case of a sudden thaw the water formed by the melting of the snow cover could have readily infiltrated into the soil of those areas where the grass cover existed. here would have been comiderable runoff from the conifer plots because of the ice sheath. During the month of March, precipitation was again in the form of rain and snow. A total of 1.53 inches of rain and 10 inches of snow produced an increase in the soil moisture content of the three red pine plots. Plot 190 continued to have the highest soil moisture percentage at all levels, ranging from 9.8 percent at six inches to 7.5 percent at 36 inches. The lost uniform rise occurred in plot 80 there all three depths showed an approxinte increase of 1.5 percent. By March 26 .plot 120, which on February 28 had been below plot 80 in soil moisture «,4 "C‘ . . . . . . . a . v . e n I“ )I \ 0,45 _ s n r . n‘ U u (n . ’1 I e O- 9 . . . . . t . . . .1 ‘46 content, now was slightly higher. Melting of the snow cover in addition to regular precipitation was producing a noticeable effect by raising the moisture content of the soil. Differences in both depth and distribution of the snow cover throughout the three plots were very noticeable throughout the winter and early spring seasons. The snow cover was deepest on plot 80 on February 28. By March 26 the remaining snow on plot 80 was confined to the large opening between the trees, see Figure 17. Approximately 60 percent of the stand was covered by snow, which averaged six inches in depth. Slash beneath the crown canopy and that thich protruded above the sun was entirely free of snow. Evidently heat absorption by the bark am dead needles of the slash had greatly accelerated the melting rate of the snow around it. Plot 120 was visibly different from plot 80 on March 26 in that the renining snow cover was only 344 inches deep. It was not confined to openings as in plot 80. 0f the total area, about 90 percent remained covered with snow. Bare spots averaged about five feet in diamter and often radiated out from some particular tree. Heat absorption by the bark at the base of the tree had probably initiated the melting process and as the needle litter became free of snow. it too absorbed considerable heat to further the melting process at an increased rate. On plot 190 the snow had averaged only seven inches in depth on February 28 3 by March 26 the snow nantle was reduced to an average depth of three inches. Circular bare areas about 18 inches in diameter surrounded the bass of every tree. h? The pins plantation had served as a snow fence for the field north of it. On March 26 a belt of snow paralleled the plantation and extended out into the field 60 feet. The two thirds of the snow belt nearest to the plantation averaged nine inches in depth. The remaining one third tapered gadually down to the exposed grass cover thich began along a, line 60 feet north and parallel to the plantation. In the surrounding jack pine forest no snow remained.on the ground. This was in contrast to the red pine stands because the Jack pine stands are also rather dense. The thinner crown of the Jack pine. undoubtedly pemitted larger amunts of ligt to penetrate to the ground, thus greatly accelerating the rate of melting. This was substantiated by the grasses and herbaceous shrubs growing in the Jack pine stands. This type of ground cover appears to favor rapid melting of snow, and, in combination with the relatively large anount of light mich can penetrate the Jack pine stands, conditions were favorable for the rapid disappearance of the snow cover from those stands. Observations of the snow cover on April 1 revealed that consider- able melting had occurred in the six-day period lapsing since March 26. The snow belt adjacent to and north of the plantation had receded from 60 to 30 feet in width. It now tapered from an average depth at the center of eight inches to exposed ground cover at each side. In plot 80 no frosen duff remained. The remaining snow mantle was limited to the crown opening and covered only 10-15 percent of the total area. The average depth of the snow was approxintely four inches. Sunlight can readily penetrate to all portions of this stand, consequently only previous heavy accunulations of snow in the crow: opening remained. ‘t \ . f‘ O .. f e -. aq~ 1 "fi 4 U . 1» e z .s n 4 " C e e VI F 1 V. _. x 7', 1 (O ‘.r\ *\ v \ . . . a \ sblq s ' “ I > s . .“ .\.w :7 n l I 8.. < I u \ t "r I F' c F u-. e .. e f' . . ‘ f O \ ' " p‘l‘ . o" " '" _ .s .‘ '- ‘ ‘ _‘. I. ,4 l . . . ,. l .. - . v . r' I I ‘ .- t . . n \a . v ' ., . n _ v , . y 8 fl V ,-.‘r l’ . I .' r . t . . ‘. . ~ rs- \ ‘ ,~ A n .d . . !‘ . _\ . ’7 .l ‘1; 148' Considerably less sunlight penetrated into plot 120 ; scattered patches of snow covered 20-30 percent of the area to a depth of four inches. In this plot the duff was still frozen arxl averaged l-1/h inches in thickness. The most dense stand, plot 190, rennined covered with snow, averaging 2-1/2 inches in thickness over 70-90 percent of the total area. In addition to the one-inch frozen layer of duff, the soil was frozen to a depth of one inch. On the southern and eastern edges of this plot, oblique penetration by the sun's rays had resulted in a very rapid disappearance of the snow cover. On April 1, the soil samples for plots 190 a!!! 120 showed that at the six inch depth the two plots had moisture percentages of 10.8 and 10.6 respectively. These percentages represent the highest amount of moisture recorded for the two plots. Plot 80 on the same date showed no increase in moisture over the recording for the previous week. The disappearance of practically all of the snow cover on this plot by April 1 was pobably the reason for the lack of increase in soil moisture. At 18 inches all plots showed an increase in soil moisture. At this soil depth all three plots attained'the mm moisture content recorded for the study. it 36 inches plot 190 attained its maxim moisture content of 7.7 percent. From February 28 to April 1, plot 190 maintained an almost constant moisture supply at the 36 inch depth, averaging 7.5 percent. The beneficial effect of snow cover in building up the soil noistm supply had reached its eptilum by April 1. {I 1 At a. r ‘ . ‘ e v u‘ r I D e . , . s 't r. ‘- _l D e J- o ' ' . \r: - l I ' " , x v '5, _ ' ‘.J . _ n‘ . .~ w I. e u a e , .. , C l r 1"- .V Irr— . O n -. rs ‘4' r v x. " w . , ' ‘.- w o . . . A. ‘ . \ *lrl ‘\ .L . , J . , F . , a I l‘ l . '\ - ea ‘ e h8‘ Considerably less sunlight penetrated into plot 120 ; scattered patches of snow covered 20-30 percent of the area to a depth of four inches. In this plot the duff was still frozen arr] averaged 1-1/h inches in thickness. The nost dense stand, plot 190, remained covered with snow, averaging 2-1/2 inches in thiclmess over 70-90 percent of the total area. In addition to the one-inch frozen layer of duff, the soil was frozen to a depth of one inch. 0n the southern and eastern edges of this plot, oblique penetration by the sun's rays had resulted in a very rapid disappearance of the snow cover. On April 1, the soil samples for plots 190 and 120 showed that at the six inch depth the two plots had moisture percentages of 10.8 and 10.6 respectively. These percentages represent the highest amount of misture recorded for the two plots. Plot 80 on the same date showed no increase in moisture over the recording for the previous week. The disappearance of practically all of the snow cover on this plot by April 1 was pobably the reason for the lack of increase in soil noisture. At 18 inches all plots showed an increase in soil moisture. At this soil depth all three plots attained'the maxim noisture content recorded for the study. At 36 inches plot 190 attained its marina moisture content of 7.7 percent. From February 28 to April 1, plot 190 maintained an almost constant noistm°e supply st the 36 inch depth, averaging 7.5 percent. The beneficial effect of snow cover in building up the soil moisture supply had reached its eptilnn by April 1. re r— . . . 4 ' ‘ A, | ‘ U ‘ A ‘ ‘ - . . ; - » . r- (r ‘ .7 . ,--v - n v I" n ' n: . , e « re \ - l ' . . 1 . ' \ l ‘ . . .- . .r‘ - . . ' V F. ‘ .J. F ' .. . . l) a . ' ‘ I - v . . F -fi “ ‘ - A -V\ r l " A n » V . . r . . _ ' r A( _ ‘ vs ‘ ‘I ' w - A . _\ A '- ‘ - . . ' I J. t. ' ' " - ’ , I I ‘ . v7 . t . - . a 1» g . - K 'x’ ' ' ' v . . . . f) 8" "' ‘ ' A ' ~ “ r ‘ - ', - -~ , ‘ \ I‘ l .1 ' r ' 0. . . a e u r . . , ' ‘ . ' . . l r ' " “i r 1‘ P‘ <‘ n . . . . .A' - . v 1 v I ‘ . - - . . - ' . H I I " ’1 ' ‘7 P ‘ ‘ A ' ' t I ' Vr \r ' u a . - e , 1 - - , h _. e r ,. . '.‘v\A. ,- ‘ , 1 0’ ' ‘l e‘ - ‘7: ‘ . ' .. r a) -. I l . s u . e . e . . . , - _ . e r (. .e - a, . . . . - V. A ’ V " * -a t . . -‘ A . (e‘ - .- g' . ‘1 . r I .~ ' f‘rl . 4 ¢ ‘ a— - L ‘ e r “v , -.| ~' I" .‘r ,. ,\.,- ,, h , ‘r'._ I g . ' A 4 3 'J‘ ‘ "\ . .- ._ .I. . « ' ' ' ° ' I‘ I r s v n e ' . ‘ .\-’ He", ’ 1 ' ‘ . l‘ 7' _ ' ‘._ — K ' ' , a \J a a \ .. n _ i . p e . r f v _ |_ ‘ " .‘ ..’. " , . . I . u ‘ . \ a e h8' Considerably less sunligxt penetrated into plot 120; scattered patches of snow covered 20-30 percent of the area to a depth of four inches. In this plot the duff was still frozen ard averaged 1-1/h inches in thickness. The most dense stand, plot 190, remained covered with snow, averaging 2-1/2 inches in thiclmess over 70-90 percent of the total area. In addition to the one-inch frozen layer of duff, the soil was frozen to a depth of one inch. 0n the southern and eastern edges of this plot, oblique penetration by the sun's rays had resulted in a very rapid disappearance of the snow cover. 011 April 1, the soil samples for plots 190 and 120 showed that at the six inch depth the two plots had moisture percentages of 10.8 and 10.6 respectively. These percentages represent the highest amount of moisture recorded for the two plots. Plot 80 on the same date showed no increase in moisture over the recording for the previous peak. The disappearance of practically all of the snow cover on this plot by April 1 was pobably the reason for the lack of increase in soil noisture. At 18 inches all plots showed an increase in soil moisture. At this .011 depth all three plots attainedthe mm moisture content recorded for the study. At 36 inches plot 190 attained its maxim moisture content of 7.7 percent. From February 28 to April 1, plot 190 Iaintained an almost constant moisture supply at the 36 inch depth, averaging 7.5 percent. The beneficial effect of snow cover in building up the soil moisture supply had reached its eptilun by April 1. I l r" u... ( -.. 3 ,.l 1! I - s V . J u ,.,- ‘e r f' e “'3, .\ ,- .': f‘ r l W '1 r. .. v e U s ‘. .1 ‘. ’ . . , I I I 1 e .5:- \ .. .1' F —-~...— I ,. O r .3'. C- '2’) "r W, ,- 1 rr, 1 " ' . _\ . e. V! \: o‘fs- _ .e h? Total precipitation for April amounted to 3.h9 inches of rainfall and 0.1; inch of snow. By April 18 all of the winter snow cover had melted. However, it had snowed the day before and it was still evident in plot 80 as there was a trace in patches averaging approximately 10 inches in diameter over about 10 percent of the area. In plot 120 a trace remained over to percent of the area. In plot 190, one eighth inch of snow covered 90 percent of the area. No snow was evident either in the open field or unier the jack pine stands. By this date all the duff had thawed out and the last vestiges of winter were practically gone. At the six inch depth all plots were at an approximte equal moisture content of 9.5 percent. A11 plots, except plot 80, had descenied from their optimum-level attained on April 1. The field samples revealed a gain in moisture content for the open field. At the 18 inch depth, on April 18, all plots receded uniformily in moisture content. At 36 inches, plot 190 showed a sharp drop of 2.5 percent. Plot 80 decreased slightly and plot 120 increased to a moisture content of 6.1 percent (Figure 21). I From February 28 until April 1 the melting snow cover in comi- nation with. additional precipitation in the form of rain or snow had recharged the soil moisture supply to its maxim level in plots 190 and 120. Plot 80 did not reach its peak‘at the six inch depth until May 2. On that date the soil had a moisture content of 10.8 percent of oven-dry weight. rr '1 ~ \ 2 ’ 3 50 Plot 190 showing the snow cover existing at the std of March. March 31, 1953. Fig”. 15s 0" fir/nil). 51": " g ‘ ”fixated, Figure 16s 1"”.- Plot 120 showing” the snow cover on March 31, 1953. 52 Figure 1?. Plot 80 showing snow cover on 53 Figure 18. The snow belt concentrated on the north edge of the plantation. m 31: 1953s Figure 19. Jack pine stand on Harsh 31, 1953, showing dense mat of grasses. SS S6 Variatiom in Soil Moisture Supply During the Growing Season The growing season began gradually. Most noticeable was the increase in air temperatures. On May 1 the recorded air temperature was 39'F., but by May 9 it had risen to a very warm 79‘F. On May 9 the Jack pine buds were beginning to open up; the red pine buds were noticeably swollen, but they did not begin to open until about May 16. The first three days of May had a total rainfall or 0.51 inch and the soil moisture supply in all three plots was at a ma: level at the 6, 18, and 36 inch depths. On May 2 the soil samples collected showed that at the six inch depth plot 80 contained 10.8 percent moisture, plot 120 10.3 percent, and plot 190 8.9 percent, as compared to 10.9 percent in the cpen field. At the 18 inch depth the order was open field 8.3 percent, plot 190 7.5 percent, plot 120 7.2 percent, and plot 80 6.7 percent. This pattern of moisture distribution had been evident in all three red pine plots since February 28 at this depth. The same order of moisture abundance occurred between plots at the 36 inch depth. Plot 80 had noticeably declined in moisture content at the 36 inch depth since March 26. The rapid disappearance of the snow cover in that plot had evidently adversely affected its moisture supply at the 36 inch depth. Except for a rainfall of 0.23 inch on May 12, the period from May 1; to May 16, inclusive, was devoid of any precipitation. This lack of rainfall was reflected in the soil moisture content for the period. At all three depths there was a noticeable drOp in soil moisture. It was during this period that growth had started, but illicit-I'll! Ell ‘ S7 transpiration from the crowns must not have influenced the soil moisture content to am great extent because the moisture drop in the plots and open field was almost uniform in all cases. During this period the open field and plot 80 differed but slightly in their moisture content (Figure 21 ). At the 18 and 36 inch depths all the plots were at nearly the same moisture content by May 16. ‘During this period, fluctuations in soil moisture occurred among the plots. At the 36 inch depth plot 190 had a higher moisture content for the period than the other plots. Fr0m May 16 through June 6 precipitation was abundant ani well distributed as indicated in Figure 20 . The total rainfall for the period amounted to h.63 inches. The response in soil moisture was evident immediately in all the plots as the soil content started to increase. The cpen field had a higher soil moisture content at 6 and 36 inches during this period than any of the pine plots except for plot 80. On May 30 plot 80 had a higher moisture for the period at the 6 inch depth than either plot 120 or 190. The latter two plots fluctuated among themelves in moisture abundance. Plot 190 showed the sharpest rise of the two plots for the period - 5.6-9 percent. For the period, the three red pine plots maintained the same order of moisture content at the 18 inch depth. Plot 120 had the hidmst moisture content, followed by plots 190 and 80. The open field cm shows a marked drop for the period. There was a sharp drop in precipitation from June 6-13. After June 13 the rainfall occurred at rather regular intervals. The total Cumulative rainfall in inches 13- 114 10* \O J 31 2- 11 l l; 58 I]. 16 23 3 Figure 20. J 13 20 June 2‘7 h 11 18 25 1 Jul! 8 15 22 29 August Cumulative weekly rainfall. A 1 .~ ,- . w _ ' .‘ .5 . . N O 48" . s\ r r. K I" ‘ q I e e , Cumulative rainfall in inches 13~ 11‘ 10‘ 58 [LII] . 162 3 Figure 20. 13 20 27 b 11 18 25 1 8 15 22 29 June August Cumulative weekly rainfall. V, n v... () Cumulative rainfall in inches 13- 11‘ 10‘ 58 ILIH Ll 16 23 3 May Figure 20. 13 20 27 h 11 18 25 1 8 15 22 29 June August Cumulative weekly rainfall. 59 Percent 10-« a I E» Q 1 f3 . +5 5‘ \O “ ----- Plot 190 1 ‘——"'—— Plot 120 -—-- Plot 80 - Open Field 1 1 L L l L 1 1 1 1 1 1 10a .1 33 i 8 . .5 q #351 Q d H J L g l 1 _L L J L l J 1 10d J l L 36 Inch Depth um l 1 1 J 1 L 1 1 1 1 1 41 Feb e Mar e Apr e May June 28 26 1 18 2 9 16 23 30 6 13 Figure 21. Soil moisture expressed as percent of oven-dry weight. 18 Inch Depth 6 Inch Depth 35 Inch Depth Percent q ——--- Plot 190 -——--—- Plot 120 Plot 80 Open Field June July Aug. 20 27 h 11 18 25 1 8 15 22 29 Figure 22. Soil moisture expressed as percent of oven-dry weight. 61 for the period June 6 to July 14- amounted to 1.1.10 inches. Most of this rainfall occurred on July 1 when a total of 2.35 inches of rain fell. There was a noticeable decrease in soil moisture from June 6 to 27 in all three plots at all three levels. At the six inch depth, plot 80 had the highest moisture content for the period followed by plots 120 and 190 in that order. The drop in soil moisture for the three plots at the six inch depth was approximately 11.3 percent of the oven-dry weight. At the 18 inch depth the approximate drOp in soil moisture was from 7 to 1; percent. The 1; percent moisture content of June 27 repre- sented a new low for this depth, as did the 5 percent moisture content at the six inch depth. At .36 inches the plots were at a new low of approximately I; per- cent moisture content. Plot 190 had a higher moisture content than the other two plots. On June 27 the open field had a moisture content of 7.8 percent. This was considerably higier than the moisture content of any of the three plots. This trend. at the 36 inch depth continued until the conclusion of the study on August 29. Apparently a cover of gasses and low shrubs is very favorable for increasing the soil moisture supply at the 36 inch level. A heavy rainfall of 2.35 inches on July 1 brought the soil moisture content up in all plots and at all soil depths, except for plot 120 which decreased by 0.2 percent in moisture content at the 36 inch depth. On July I; plot 80 showed a moisture content of 8.0 percent at the six inch depth. Plots 190 and 120 were at 7.3 and 7.2 percent respectively. At 18 inches, the order of soil moisture content as: ‘ . , . r I - _ A .a O , _ O ’ _ _ . L . - x I o “ ' . r- - - w » ‘ q - #7 F. - . - - ' ' ~ r ' I I I ' ‘1 n C ‘ ' . r- . v . ' ‘ I - ‘ -(n ‘ K'\ ‘ . . . a ~ Q . r A o ‘ .‘ 1 . ' 1‘ n '_ r ' ’ m - ‘ ' 1'“ , . . I V v r I r ‘ ' . " ' “a . q. .’ t , ,... '71, , . Inn y \ ‘ ' I , -"' ~r ' . ‘ ' ' 1' “ ' . \ J ‘ ' , N. ‘ > I ~ '1‘ q u . ' l e . U? A“ \1 ) In -. r‘ 1 0 U - v . l m h . —' " I r“ ‘ ' If ‘ I ‘ e e . r I ‘_V . , . ’ .l -.‘\ ‘ V I ' . ‘.K r N , I‘ '.J |_, . l () I , ,‘> . . -, ..‘ . . . ,‘ r, . e . r. a I I - . I ‘ ‘ - __. H s . .- 1 ._(- 3 rs. . . W : v ' " \ k .. \ ' .' . r1. ' y- . -e .- ' v e “ \ " ‘ . ‘A -‘ ' ' T fl'I 4 V I, _ " I. ' ‘ ‘ \ ‘ ‘ J ' . " "t I " I v - , ' O 9‘ -, .) n, e f ' '1 " ‘ ' ' . I . Q! I ‘ .- u l4 1- V ' ' -- ‘ e U "‘ u ‘ _ f‘ \ "‘r . A! r"; . . i, s i ( - - - ' \ , r‘.‘ . I ' 'I< H". r . , ‘ ’5 A. - .T 1‘ In I'— :- - \ . i . 'J »~ ' V I ~. ‘ . '_| . r‘_ s‘ _,, a'. . a .I "‘ Fr- - .p e , '- - ‘» l " 1 ‘ ‘ 1 t a '_C., u :0 d z of“ -. . M a t 31.... .. r I t x -1.“ '_V_ _ ' .1 . .'. C . .1 Yr). :‘r :r' ' I 1‘ .- ‘O \‘_- fl. \ .l. .4 .a '- N 4.- -. 1' .4._‘. 62 plot,80 6.0 percent; plot 190,5.8 percent; plot 120,5.6 percent; and the open field ,5 percent. Differences in soil moisture between plots here more apparent at the 36 inch depth more the order was: open field, 8.2 percent; plot 190, 5.3 percent; plot 80, h.2 percent; and plot 120, 3.5 percent. The period from July 5 to August 1 was characterised by a very low rainfall. The precipitation which occurred was practically limited to July 18 and 25 when 0.82 and 1.03 inches of rain fell on the re- spective dates. The air temperatures for the period were mostly in the 5. Diddle 70's and low 80's. . ‘7"; From July hall, only 0.214 inches of rainfall had occurred. This shortage of rain was reflected in the soil moisture determinations for July 11. A drop in soil moisture occurred in all the plots and the open field at all depths. A rain of 0.82 inch on July 18 raised the soil noisture content at six inches in all the plots and in the open field. At the 18 and 36 inch depths the soil moisture continued its downward trend in all the plots. Only the open field showed a rise in soil moisture at these two depths. Undoubtedly interception, absorption, and retention of precipitation by the plantation canopy and litter in the red pine plots before it could get past the six inch depth were the principal reasons for this trend. In the open field there is no highly absorbent needle litter; consequently, rainfall can quickly percolate to the lower depths of the sand soil. On July 25 another heavy rainfall of 1.03 inches occurred. At the six inch depth in all the plots the soil moisture content rose again (Figure 22). The soil samples collected in the open field showed ‘ o o e C ‘ , j . - ‘ F.1- I — . . e 5 ’ - , e . . . | ’ - . U f ' - ‘ . . , 7‘ . . . . . I ‘ . . ,I - e v 7‘ I 1‘ I e ( I . . . ' \ ‘ ‘ i - O u ‘ ‘ \ ‘ ' , ' - -. a \ , . P F . I I ' _ ’ _ \ > n I . N N -, - 63 a very high soil moisture content of 10.8 percent. Plot 120 surpassed plot 80 with a 9.0 percent vs. 7.6 percent moisture content. Plot 190 remained relatively low with a moisture content of 6.5 percent. At the 18 inch depth plot 80 rose to 5.2 percent. Plots 120, 2.7 percent, and 190, 2.3 percent, continued their downward trend which began shortly after July 1;. At the 36 inch depth all the plots continued their dom- flard trend or remained the same as on July 18. From July 25 to August 1 only 0.06 inch of rainfall was recorded. All the plots showed a considerable drop in soil moisture. The most noticeable decline occurred in the open field where the soil moisture ""5 dropped from 10.8 percent to 3.2 percent. At the 18 inch depth the open field, plot 120, and plot 190 showed the same noisture content of 2.5 percent. Plot 80 was slightly higher with 3.1 percent soil moisture. At 36 inches all the plots were at a moisture content of 2.5 percent of oven-dry weight. Low as this moisture percentage was, it was to drop even lower before the conclusion of the study. The total rainfall for the month of August was 2.93 inches. Actually, sore rain fell than in June, but the water content of the soil at the lower depths was at a more critical level. The most promi- nent precipitation periods occurred as follow: august 2, 0.22 inch; August )4, 0.72 inch; August 8, 0.67 inch; August 12, 0.63 inch; August 21, 0.20 inch; and sag-n.1, 25, 0.28 inch (Figure 20). The combined rainfall of August I; and 8 raised the soil moisture content at six inches to favorable levels. In the open field on Augmt 8 the moisture content was at 10.8 percent. In the red pine plantation the soil moisture distribution was as follows: Plot 80, I ,.A ‘4 -‘ ..‘. . . .I l ‘1 fl. 0 ‘ ‘Ao- A .I f, I . -r‘ r r, v» " < O -. ' 4 1 _ r i . C v . . "1 . \ . 4‘ i . I .\|. ~, [- ‘,- r if 3 —~ ' r 7" ¢\ .' , l , . .— «V I l ' i- C r " ‘ f‘ ’ .' x ‘ . ' a . . e‘ ‘ ‘ "\ ‘ f“ ‘\ ‘ u "‘ O W L) ‘ 'I I ‘ . r . \ fl A 1 t , n - . A r‘v - u ~J .rI ‘ ‘ I I r ' ‘ ’ (\l \l I '- _ U . .' " - fi' ‘1‘ s . { 1 r_' I, . , . ' 1" .. - I r -- I a e « . I v n I‘ I ‘ h a O 4- ‘ . ' c n . T If . r . ‘ ' ' J‘ r .. v . . C u . ' .4 . .. \ ._ _ , f." _ \ s 1 u , I Q . r . a '3 .3 .. . -‘ ‘fl‘ , I 7‘0" .‘ - . I .z " oer o n - r . I O ‘ \. . O . u . . \ -\. ,. n ‘ , . C ‘ v . - ,‘ ’1 ”f 7‘ re , ‘ ‘A r\. v . I ' I l ' , _ - I r," . r a k . ‘ I D r r \ 1 r 0 . jpr ‘ I .‘ I Y A. ' - n \ \J L; I .f . I‘- {'1‘. r. ' ,., , Fl"), ' e _l f s. . - ’ A , . 'fi ., \v K U f“ I I . . fl ‘ I r'- '- » ., (‘7 a.“ .n .A ‘ .l, "v H a’.‘ «yr 2"“. I ‘ r-vq- e \~ A- - . —. ._- . . ~or ,2 a ___,_1.v.—a _ 6h 8.5 percent; plot 120, 7.2 percent; and plot 190, 5.1; percent. Except on August 15, plot 80 remained above the other plots in soil moisture content at the six inch depth. On August '29 the plots were all at an approximate moisture content of 2.7 percent. it the 18 inch depth througxout the month of August, the plots varied between moisture contents of 2.5-3 .5 percent. Even though the variation was small, the order of decreasing soil moisture in the plots was plot 80, 120, and 190. During this period the open field had moisture contents on August 15 and 22 of 6.5 percent and 5.5 per- cent. These percentages were approximately double those which were recorded for the plots. On August 29 , however, the open field had the lowest soil moisture average recorded during the entire. study for the 18 inch depth (2.2 percent of oven-dry weight). For the period August 8-29, soil moisture differences at the 36 inch depth were more noticeable. For this entire period, plot 190 constantly had the lowest soil moisture content (Figure 22). The lowest recorded averages for this depth, 1.7 percent on August 22 and 29, occurred in plot 190. Of the three red pine plots, plot 190 on August 1 had the lowest recorded soil moisture content at the six inch depth (2.6 percent); on July 25 it had the lowest average recorded at the 18 inch depth (2.3 percent). Thus, plot 190, with a basal area of 190 square feet, exhibits the most pronounced soil moisture fluctuatiom when compared with the other two red pine plots. In March and during the first week in April when the snow cover in plot 190 was melting at a slower rate than in plots 120 and 80, it had the highest soil moisture content at all three fl. '5 ‘ \ O .\ ’ p, , . - l q ._ , . ‘\ , e .. - I D l‘ l " r r e- .‘ J. . ' . -r .4 ‘ . \ 'z-f‘ .. . t l . . I - . \ \ \ .— . . . .- . \ ' Q I, .- l‘ . I. . .. - . (W \I . ~n- r“ ' l_ . ,l “ , h _ r .. , I ' l l a. ‘ ' I I. 'fl 'A ‘V .0 “"i' I . _- . , r‘fiqy ‘I —- r 0"" r .l . _I ,‘A 1 . u ‘ . I -. q. . a. , V A. . ‘ C . ".f '\ . . - W "I" ‘ U 1 u I A. . . \ c \ ,_‘ , I l 3 -~ — . 'J c «r y. . . .- - . y. f“ ,\ a A r. ,- r _I Ir " ‘\ . ', U a. O f“ "“" v I T) Y ,1 ‘ , O -, l . r I A & \4 \ I fir C ‘l H. '. a‘ ’ r-‘fi fi- .4 ‘ I "v rr" F r”... ' ’6 '\ . P' " ‘ l W I. 6h 8.5 percent; plot 120, 7.2 percent; and plot 190, 5.1; percent. Except on August 15, plot 80 remained above the other plots in soil moisture content at the six inch depth. On August ‘29 the plots were all at an approximate moisture content of 2.7 percent. At the 18 inch depth througlout the month of August, the plots varied between moisture contents of 2.5-3.5 percent. Even though the variation was small, the order of decreasing soil moisture in the plots was plot 80, 120, and 190. During this period the cpen field had moisture contents on August 15 and 22 of 6.5 percent and 5.5 per- cent. These percentages were approximately double those which were recorded for the plots. On August 29, however, the open field had the lowest soil moisture average recorded during the entire. study for the 18 inch depth (2.2 percent of oven-dry weight). For the period August 8-29, soil moisture differences at the 36 inch depth were more noticeable. For this entire period, plot 190 constantly had the lowest soil moisture content (Figure 22). The lowest recorded averages for this depth, 1.7 percent on August 22 and 29, occurred in plot 190. Of the three red pineplots, plot 190 on August 1 had the lowest recorded soil moisture content at the six inch depth (2.6 percent); on July 25 it had the lowest average recorded at the 18 inch depth (2.3 percent). Thus, plot 190, with a basal area of 190 square feet, exhibits the most pronounced soil moisture fluctuations when compared with the other two red pine plots. In March and dm'ing the first week in April when the snow cover in plot 190 was melting at a slower rate than in plots 120 and 80, it had the highest soil moisture content at all three l l t . .\ . . ‘ \ x \ I U I \‘ \ r I f I I (' i . ' - -’ F' I ' , --. p '1' .\ 1 , ‘ . cu“. ' ‘ ’— A I L 9- :- ‘I‘ f“ fl- V r" — e ~ ‘- ‘ _l -- r, x a .7 o l . , . v . q ,- .‘ n "\ f'\ ,— . NI I ' r H‘ . d \ >‘ a. e -- --r f "— J. A .‘x‘ . . e D l ‘ ' [Jr-7"" . - ‘ ‘ I. (‘ ” r)” v ".' " ‘ ’\ I I“ .' ’\ l I -L ' -r t \v . { '4 -‘ C A ‘ e fit ' ' Q . - \ I { . ~\ ,7, .. ' T- r °‘ r r ‘ ' "V's r ‘ ‘ ‘ ‘ p . v- — l I I ’1 I ' r , , . ,. r. C . e - n \ ‘ - I rvnvf | x . ' ‘ .- I I ,. _ D . l ’ C q ‘, \ IK-n r‘. e I ' I \n. . q- ' . I . a, f . - h-' r r C a ' ‘.lr .\ ~5- r P. 'r-r x H r '.l . v" - ‘ ‘ ‘ qfi., . , . — ‘ .A | _ r I I '_ ’ l 3‘ . ‘ i "' u"- Q l— ‘ . :.J '(‘T r ‘: "-° ' ‘YV‘ ,. .L ‘ ' y -_ C‘\ u 3 if" .'. . e r_ e - w ‘ A O ) -. 6 ‘ I 3. ‘ ‘I t l-l 3 ~... I . ‘4 ‘ F .‘ ‘ ‘ -. —~ .f * fit ‘I - ‘I v - A 2‘ , t . f. e n r. ,vn - I“ r“ I '\ L O h I l I - F v I r. r. I . O I. I _ W - V I n‘ A \a s . l C q. - C‘. , . (v ' n ' ' _ l “'r‘ ‘(\ v . ‘ ~. . e r I I s l '.' r A“. -n- \. .'. ‘— e r- ‘. ”\ n a. 'F ( . x . I A .. -‘. L. . Pee 6h 8.5 percent; plot 120, 7.2 percent; and plot 190, 5.1; percent. Except on August 1‘3, plot 80 remained above the other plots in soil moisture content at the six inch depth. On August '29 the plots were all at an approximate moisture content of 2.7 percent. At the 18 inch depth througxout the month of August, the plots varied between moisture contents of 2.5-3.5 percent. Even though the variation was small, the order of decreasing soil moisture in the plots was plot 80, 120, and 190. During this period the open field had moisture contents on August 15 and 22 of 6.5 percent and 5.5 per- cent. These percentagee were approximately double those thich were recorded for the plots. On August 29, however, the open field had the lowest soil moisture average recorded during the entire study for the 18 inch depth (2.2 percent of oven-dry weight). For the period August 8-29, soil moisture differences at the 36 inch depth were more noticeable. For this entire period, plot 190 constantly had the lowest soil moisture content (Figure 22). The lowest recorded averages for this depth, 1.7 percent on August 22 and 29, occurred in plot 190. Of the three red pine plots, plot 190 on August 1 had the lowest recorded soil moisture content at the six inch depth (2.6 percent); on July 25 it had the lowest average recorded at the 18 inch depth (2.3 percent). Thus, plot 190, with a basal area of 190 square feet, exhibits the most pronounced soil moisture fluctuations when compared with the other two red pine plots. In March and during the first week in April when the snow cover in plot 190 was melting at a slower rate than in plots 120 and 80, it had the highest soil moisture content at all three r l \ . \ r N (‘r nest-s ’ I U I. r“. Jr A o l’\ r \ t , ‘ ‘- . , C ‘ . \‘ e I' . ' P /. 4 I I ‘ r v . e ' e t . , ‘ , I u I . ~J" ‘ ‘ ‘ ' , n . , , . .- t r ~ ~ e . I“. \ n ‘ ‘ - I . *N' \_. ' t ‘.s v I r ‘ " 1(- 1 L. W 7 fl‘ ' an. ‘ W ‘ u .4 . " i V r V " W ‘ ‘ ' ’ V . ‘. ' . \z _ . . p. I n . \ . . a . . ’1 - '2 .I . l' ‘ F. n‘ ' I I .n l . .’I . I . I ' F‘ '- . ‘ \- I] r~‘ I .—. ~ . V I ‘ \ a II D I . i . . ‘ . r\ "I w ‘ r I .' I“ V - I i , 4 . L L d ' r , . . P fi‘ ‘ , r ' ~ . u l \ . . I-I r -'l ‘ ' \ .- I . 4 I ‘ I ~ ‘I ‘ ‘7 “ 1 :3 ' I . I w A ', r \ - \ . ‘N ‘ ' r J" r I ' r "‘ u V. -. . ‘- ~-.~ ‘ 4 - y“ ‘ r , . . e . e I. . . , r I - . \ , r- I II ‘ ' n ‘ A‘ . \‘s ‘ ' ‘ f‘ . ' ' 7‘ .' U r‘ C { \ . e ‘ _~ \ ' e u "\l" _ fl . 1‘ \. . t O .- a . . ‘ . \ - I r n ‘. ., . ,n . r r (f l » g. l e . ‘. _.- . 5 . . I I '.- n « I ‘A r- “ ‘ '1 \ L; .r "‘._x-. .- u “U ' a V . e . r "r‘ I. M ‘_ I e O ‘ x-- - ' . . I-r' I r ' . z \ . - I‘A , \ . A _ ( I . U 7 - U - ‘1 _ ’ '( . . . . r . I ~- ,n, ‘ , r . _ — - x ‘ -. 1 - '\ V I r. q '.l. L; I r . ,r A ‘J .‘1 'l ‘ a ." F . A r» ‘ a . \ . i a . ’3. I l \ u (- . \v I _ e \‘ 6S depths. Late in the growing season when the heavy tree population of the stand exerted a tremendous moisture demand from the soil through its very dense root system, the situation was completely reversed and plot 190 exhibited the lowest soil moisture percentages. Statistical analysis did not disclose a significant difference between plots for the season as a whole. Analysis of Variance Source Degrees of Sums of F Freedom Squares Mean Square F Book Total 65 330 Between 2 13 6.5 1.30 3.15 Within 63 317 5.0 21 and 22 However, close inspection of Figures/ will disclose that during the paving season 82.1; percent of the time plot 80 had the highest moisture content at the six inch depth; plot 120, 11.8 percent; ani plot 190, 5.8 percent of the time. The only time during the growing season that plot 190 surpassed the other two plots in moisture content at the six inch depth was on May 30. During the week of May 23-30, 1.62 inches of rain had fallen and the maximum moisture variation between the plots at that level was «1110.1. percent. It is quite conceivable that with such a small amount of variation and for the number of samples collected that the usual order of moisture abundance between plots could have differed ' . a - ‘ - ’ t I o O ‘ ‘ V . v r‘ -‘ C O . e A ' q . . l . . 1 r- I ‘ ‘ P 0 fl 7' \ ,\ » _/ J W P ’1. A f , r p. I - ‘ - L ‘ - - \ ‘ f v‘ \ , O \. . ‘ . i I" ‘\ ' I r P . r \ I ‘ . ’ A 7 ‘ v/ F‘_\ - Fl '3 ' ; / >‘v i . o ca 7 ‘ I . . ‘ - . l 7‘ J u- I I r I I ' M 7‘ ‘ C r- * I - A I ' . . ‘ -‘ ' fl ‘ x. i r . f . 0 , "‘ . n f \f l . - I ‘ I ‘ I . .‘. . I . T I ' '. ' l ‘ . r ‘ ' I‘ t - ‘JC . , , . e . l ' ‘ ‘ . I r l ., fl - “ ‘ r r A ‘ I 7‘ I I 1 . I‘\ F ‘ .‘ _ — r .. — I I. x ‘ ' ' I - \. . e I .' ‘ r ( A r~ ' ‘- r . l . fl ‘ ‘ ' 7" . h r .. . I 5 ~ . 0 ' ‘7 . re r- P. ‘ ‘ r ‘ . "h . v\ n r ’- 7‘ . q . n ’ Partial soil profile in Plot 190 shoeing dense use of roots. Figure 23. Figure Zhe 80. ilprofileinPlot 'ialso Part 67 Figure 25. Partial soil profile in the open field showing the grass roots. 68 69 from the customary. The same situation occurred between plots 80 and 120 on August 15. The moisture trend as shown in Figure 22 strongly indicates that at the critical six inch level, there the feeder roots are located, plot 80 had the highest soil moisture content 82 percent of the tine. when abundant rainfall tends to create a high level of soil moisture througiout— the plots, then perhaps if there are insufficient samples the usual tendency will not resolve itself. it the 18 and 36 inch depths the usual trend , early in the growing season, is a variation among the plate as to which contains the lost moisture. Differences are not nearly as large as are four! at the six inch depth. From July until September the usual trend was as for the six inch depth in that the order of decreasing soil moisture at the 18 inch depth between plots was .plot 80, 120, and 190. At the 36 inch depth, from August until Septenber, plate 80 and 120 had practically the same moistm‘e content. Plot 190 had markedly less soil moisture than either of the other [two plots. Soil Moisture Trends as Indicated by the film . Electrical; Resistance Unit Originally the plan of study had called for the determination of the soil moisture variation between the red pine plots by using nylon electrical resistance units. The units were carefully installed at random throughout the three plots and the cpen field on November 8, 1952. The blocks were dry when installed because it was thouglt that they would thus be better able to stabilise to the soil moisture O ,-. . C o a I .4 ‘. x d .4 v A t . . 3. $1 1!; u .. es . a \ e . .. . r .I . 0 . . \1- I...) III!!! 1 (l. I]: o . . r o r . . J . t i . x . n o u . r . x I o . ad .6 _ ‘1 n o . ts . x V: . . J a u,. .t . (n . 70 conditions surrounding them. In December, approximately one month later, ohm reading were taken at all the stations. Analysis of the data re- sulted in the decision to collect soil samples to determine the soil moisture trend for the plots . Initially the readings were rather erratic, but by February 28, 1953, on thich date the readings were taken again, the date were such as to indicate that the resistance units had stabil- ised themselves to their surroundings during the winter months. It should be pointed out that by the very nature of the unit installation many resistance units need to be placed in the soil area for a reliable measure or soil moisture. .Once a nylon resistance unit is installed its location is fixed. If the location is too wet or too dry and does not properly represent the soil moisture conditions for the plot in which it is located, nothing can be done to remedy the situation. Unless there are drastic changes in the soil moisture regimen for the plot so that the soil situation for the plot is then properly reflected by the readings taken from the unit, then all readings taken from the unit will not properly reflect the soil moisture conditions as they exist in the plot. Even in plantatiom where the litter and humus layers have not been disturbed for many years, importantodifferences exist throughout the litter layer as to its perviousness to rainfall and cram drip. in important objective to be attained while installing the block is a minimum or soil and litter disturbance. Consequently, if the block is placed in a location where penetration by rainfall is made difficult by a relatively impervious litter layer, high re- sistance readings will be encountered. If the location selected has '\ ‘ o . o ’\ u _ ,5. \— 71 a litter layer which permits rainfall to enter the mineral soil quickly, lower resistance reading will be given by the block. The only remedy for this situation is to install many resistance units systematically at random on the plot which is to be tested. An important considera- tion encountered with the installation of many resistance units is the high initial cost. It is difficult to appraise the perviousness of the needle litter in the small area surrounding the block installation. If this could be judged, locations might be chosen which are comparable. Another very important factor which will indirectly affect the readings taken from the unit is the overhead crom cover. The more variation in the overhead canopy the more are the number of units that should'be installed. Here, again, the cost per unit may easily become prohibitive. Even under a crown canopy that is as uniform as the one over plot 190, the spacing is th, considerable variations existed in the readings within the plot on any particular day. It became obvious after the study was under way that the only possible approach would be to use the average of the units on each plot for any particular day as a working item with which to construct a graph of the soil moisture trend. is was previously pointed out, once the unit is placed in the ground it becomes fixed and is subject only to the particular micro- clinatic conditions surrounding it. The moisture trend it indicates is only for one location throughout the period of the study. In sampling a quantity which is as variable as soil moisture, it is obvious that many units need to be installed. A distinct advantage which soil samples taken at random possess is that of variability of location. C) Q . A h, ., _ Yf' - m a ' ° ‘ rv- . t ‘ ‘ ,J t \F , fl‘ I 1. "‘ , I. .\ l o i l‘ 7‘ ° n z o ' 72 Each sample taken is from a different location. This is advantageous in that the effect of any one particular location is minimized and the average of all samples for any particular day can thus more nearly repre- sent the general soil moisture condition present on that day. For the entire period of this study, any one resistance unit represented the soil moisture conditions existing at only one location within the plot in vhich it was buried. In contrast to this, each soil sample collected on a comparable basis represented the soil moisture found in 22 locations within the same plot. Other disadvantages present themselves then one decides to use the resistance units to determine the moisture content of the soil. First and foremost is the task of successfully developing an ohm- soil moisture curve. The curve is necessary for determining the quantity of soil moisture present in the soil for any given reading in ohm. For some soils this is a relatively easy task, for others, and sand is one, it is extremely difficult to obtain a curve thich approximtes field conditions. Reinhart (1953) had a very good approach to the problem in that he described a field technique for constructing a calibration curve. Each time a reading is taken it is necessary to measure the soil tempera- ture at the depth of the unit. The ohm reading then must be corrected to the temperature at which the calibration curve is standardized. This is a time consuming procedure which must be considered when many re- sistance readings are taken. For the actual relationship between soil moisture abundance and the demity of stocking complete reliance has been placed on the soil moisture values obtained from the soil samples. The gaphs of the F1 e v "v‘ . e I‘, ’l . ‘ u f}. <. ' C v 73 ohm-date trend, constructed irom the data collected from the resistance block readings, is presented to show that it is possible to follow the moisture trend of a. sani soil using electrical resistance units if’a suitable field calibrated curve can be constructed, and if a sufficient nunber of resistance unitsare installed (Figures 27, 28, and 29). The ohm-date graph for the six inch depth distinctly shows that the fluctuations in soil moisture correspond to the periods of light and heavy rainfall as they occurred during the sumer months (Figures 20 and 27). On July 25 the resistance readings were recorded for all the units between 8:30-10:00 in. With but one enceptio’n, 75,000 ohms, an the readings at the six inch depth were between 200,000-h60,000 ohms. it 10:00 A.M. it commenced to rain and between 10:00 A.M. and 3:00 P.M. a total of 0.86 of an inch of rainfall was recorded by the area rain gang. The cumulative rainfall for the week of July 18-25 was only 0.07 inch; hence, h1g1 readings were given by all the re- sistance units. At 3:00 P.M., when the rain ceased, all the unit resistances were measured again. Some of the resistances recorded showed resistances as low as 9,500 ohm. Most ofthe recordings were in the vicinity of 30,000 ohms ; several showed only a small drop when compared to the reading recorded before the rain. This indicated that the units could respond quickly to soil moisture changes. Close impaction of the unit location where h1g1 resistances were recorded showed that rapid drainage from the location before the rain water had penetrated to the six inch depth was responsible for the high reading. it the end of the season an inspection of the locations showed that the ‘0 horizon was very indurated and evidently rather ,_ ,., l r) v - .1" f‘ ..e. I' _t . ' . . , , I —." , l . ’ n -‘ '?.' _ o . V" - £3. . “ 0 Ms . um. 26. Electrical resistance measurements can be easily taken during the sinner months. Note the sack used as insulation for the portable soil moisture bridge. 7’: I " " Plot 80 —--- Plot 190 —.— Plot 120 Open Field ilk‘lllflrldl‘522'29 2 bf 23 50 1‘6 s9 26 51T 2% Feb. Hsr.Apr. May fiJi # _ 7.65..“ 3 _A.~_ A a _ a @9876 S I“ 3 2 ’ m 1 958 5 ecceafleem 20 J “1y August June Ohm resistance at the 6 inch depth at 60'F. Figure 27. .‘III‘U‘ Ilsa; Resistance in Ohm 81 /\ 7 — ' 6 6 — . \ 7 5— W \ / \ - \ h ’II‘ ._.v°'.\\ // \ 3 " I ' / ' \\ ,’ I I I 2 '4 ' I _ I I- ‘ I, 5 Il/ “ \I f I'. ‘ 'I T: 100, 4 ’/ “ l\ I " I I -. N ’ \' 7 — t\ I I, . 6 - : \'"\ a’ l a ‘ ll . 5 u I \\ , ._ I .\,- ' h '/ \\\ I \/ 3‘ r / 2.. \Wv./l/ .1 z’_ 10,000l 81 7- 64 5_ ha _._- Plot 190 _._ Plot 120 3" Plot 80 ........... Open Field 2— I r I I TT I I I I I I j_ I I T I Tir I I a 2826.31291623301320 h112518152229 18 6 27 18 Febmsr. Mu Jlune July August Aw. Figure 28. Ohm resistance at the 18 inch depth at 60'F. Resistance in Ohm 100000... 9 8— 7— 6— h-i 3d /\ /’\ ---- Plot 190 ----— Plot 120 Plot 80 .......... Open Field I I I T I I r 28 26 1g 2 9 16 36 a .201 21’ ’1' 1'1 125' 1 d 1:; 2T2 I29 31 28 13 18 Febeflardtpr . May June July August Figure 29. Ohm resistance at the 36 inch depth at 60’1“. 78 resistant to penetration by rainfall. Inspection of the graph will show that distinctions between the various plots are obvious, but no reliance can be placed on their significance because of the insufficient nuaber of resistance units used during the study. The h1g1 per unit cost prevented using any additional units. Early recognition of this deficient resulted in the decision.to collect soil samples at weekly intervals in order to obtain more specific information on soil moisture. The graph plotted for the 18 inch depth has variations correspond- ing to the high and low precipitation periods as did the graph for the six inch depth. Differences between the plots are even more clearly shown than they were at the six inch depth. At this depth the' indi- cated trends more closely follow those obtained from the soil samples. Several things are very obvious when one examines the graph for the 36 inch depth (Figure 29). The curve no longer corresponds to ' rainfall fluctuations as did those at the six and 18 inch depths. Relatively dry periods and the dessicated conditions they produce at the soil surface are not reflected on the graph until near the end of the period. The curves are in rather close agreement with the soil moisture trend indicated by the soil samples. For the purpose of illustration, they tend to show'noisture trends more distinctly at the 36 inch depth than soil samples dobecause the relatively high sensitivity of the resistance scale under low soil moisture conditions produces more marked variance on the graph when the scale of the graph remains unchanged. The graphs indicate that the deeper the resistance units are placed in the soil the fewer are the number required to obtain valid results. \ a i r . i . . PI. _ n a ._ r e . w A \. . e . e . l a . .x 3 a . _ y s l a f . . . n r V . - . J . w a. . A}. \ w ._ H \ rll. . . . r .i . a, rl . , nu \ r1, . i. . a Q a a . . , . ‘ wt . «\. ._ x . F . .i. a . q f . e “a . .3. w . \ x. r . \ .\ ( w -‘ ,‘ 79 Field Res istance-Moisture Calibration Curves Devegped For the yylon Electrical Resistance Unit for Use in Grayling Sand , Gravellz Phase At the beginning of the study laboratory experiments were con- ducted in an attempt to construct an ohm-soil moisture curve which would permit conversion of the ohm resistance values recorded during the course of the study into equivalent soil moisture values. No workable curve which would adequately represent the soil moisture values exist- ing in the field was developed. It became obvious as the experimental work progressed that the effect of the microclimate surrounding each unit on the unit at the depth at which it was interred was so intricate that it probably could never be satisfactorily reproduced in the laboratory. For some soils, satisfactory laboratory curves have been produced, but for Grayling sand, gravelly phase, no such curve had been developed. With the data available, it seemed logical that an approximation to a satisfactory curve could be developed by plotting the average of the resistance values and soil moisture values for each plot for each day the data was collected. Furthermore, the data indicated that it would be necessary to plot the data for each depth separately. The resulting curves are shown in Figures 30, 31, and 32). Each plotted point represents the average of three resistance reading, in chow, and the soil moisture content of six soil samples expressed as percent of oven-dry weight. A similar procedure was attempted by Reinharttfisj, but on a moreilimited scale. F1 rs At. I w r I F . r . . n x . . A p In "A .\ pl u . l . —.J . x 9‘ . n . _. . l _ 7 A. A a h N ., 3n- Ohm Resistanct at 60’1“. 80 1,000,000 llllll I u rmmqm fIT TI! [[11 3h56189101112 Soil moisture as percent of oven-dry weight. Figure 30. Field calibration curve for Grayling sand, gravelly phase, at the 6 inch depth. Ohm Resistance at 60"F. f3 \» er v1:>-acn<€; 10,000 coo 11L l T 1 I I T T j 3 h S 6 7 8 9 10 Soil moisture in percent of oven-dry weight. Figure 31. Field calibration curve for Grayling sand, gravelly phase, at the 18 inch depth. 1 § U rmoxqcno§ 1111 9 l N l 1 11111 1 Ohm Resistance at 60'1". U 2‘ \n Ossxcoot-O 1 ’5‘ ”’5 11 j r l I I I I I I fl 2 3 h S 6 7 8 9 10 Soil moisture as percent of oven-dry weigxt. nge 32. Field calibration curve for Grayling sand, gravelly phase, at the 36 inch depth. 83 The graphs indicate that it is probably necessary to develOp a calibration curve for each depth being tested. The curve for the six inch depth has an approximate 16 degee slope. At the 18 inch depth the curve is noticeably steeper but still maintains a linear trend. At the 36 inch depth the curve assumes a reversed "J' shape. The wide latitude between plotted values for both soil moisture and ohm resistance suggests that perhaps the best use of the resistance unit in a sand soil is as an indicator of broad relative soil moisture conditions rather than an actual moisture content. Soil Temperature Trends During the course of this study it was necessary to record soil temperatures weekly for the purpose of converting all the resistance unit measurements to a standard temperature of 60 degrees Fahrenheit. It was soon apparent that the soil temperatures at the 6, 18, am 36 inch depths usually differed from week to week among all the plots ad the open field (Figure 33). In the open field the soil temperatures recorded at the three depths were decidedly higher than the temperatures recorded for the same date in the red pine plots. The maximum variation occurred on May 9 then at the six inch level the open field was ”4.5 degrees higher than plot 80. The red pine plots varied most at the six inch depth. Plot 190 usually had the lowest temperatures at all three depths. Plot 120 often had soil temperatures which were intermediate between the temperatures of plot 80 and 190 at all three levels. Usually the soil temperatures in plot 120 tended to be more nearly f‘. . . r ._ ,, . . . I /)/‘\f 4' VI ry. '\ ' ‘ 4 .m- . - . V x): . a . \ ‘ - t i I a i ‘q‘ I a A ‘ I e ‘ . . ‘ . . e f , :- -~ A - 7‘ '0‘ n r‘. v ‘ ‘ . ’- 8011 Temperature in Degree. Fahrenheit 8h 70- 604 50- h0~ I1IIITIIIIIIIIITTIIIj 70- 60- --—-- Plot190 50- _._. P10t120 ——-Plot80 ............ OmnField hop IIUTITITIIIIII1IIIITII 70- 60- 0M \ ____ ”-- 50v laO- llfiTIIIIITIITIlillllll 28263118 29162330 6132027 hll182518152229 Feb. Mar. Apr. HQ June July August Figure 33. ‘ Soil temperatures in the red pine plots and in the open field . 85 similar to those in plot 80 than those in plot 190. At the six inch depth, from April 18 to May 9, the three red pine plots had temperatures vhich differed but slightly. From May 9 to July 18 the soil temperature differences were especially large. On May 30 the differences between the curves for the red pine plots were most obvious. On that date plot 120 had a temperature six degrees higher than that for plot 190. At this depth prolonged dry spells were occasioned by a rise in soil temperature. Conversely, periods of heavy rainfall caused the soil temperatures to decrease. At the six inch depth the recorded temperatures never went below 32'F. For the red pine plots the temperature recorded on June 20 was the maximum attained, 71'? in plot 80. On that date plot 80 and the open field were at the same temperature at the six inch depth. From June 27 to August 29 the temperatures recorded for the red pine plots tended to vary around 62'F. at the six inch depth. Referring to Figure 33, a straight line connect- ing April 18 to June 20 would indicate a rise. of approximately four degrees per week for the period. The curves for the 18 inch depth have very nearly the same trend as those for the six inch depth. Fram August 8 to August 29, plots 120 and 80 tended to be at nearly the same temperature at this depth. How- ever, for this periOd, at the six inch depth plot 120 tended to have temperatures more nearly like those of plot 190. From June 20 until August 29 the open field maintained its trend of having higher tempera- tures at the 18 am 36 inch depths; however, the 0.67 inch rainfall on August 8 caused a very noticeable dr0p in the field temperature at the six inch depth there the recorded temperature of 62‘F. was the same "\ ’3 m 86 as for plot 80. The soil moisture content of the field for that date was raised to a high level, 3.2 percent recorded on August 1 to 10.8 percent on August 8. In general, periods of heavy precipitation pro- duced more noticeable declines of soil temperature in the open field than in the red pine plots. After July 14 the trend indicated for all plots at all three depths was a general leveling of the temperature curves. The periOd preceding July 1;, except for two occasions, is characterized by weekly temperature increases. The temperature curves for the 36 inch depth show the same trend. However, temperature fluctuations at this depth- are less noticeable for similar periods when compared with the six and 18 inch depths. an approximation of the mean temperature for the period July 25 to August 29 at the 6, 18, and 36 inch depths would be 62, 59, and SS‘F. respectively. _I' [I 87 Effects of Soil Moisture and Stand Density On Radial Growth As nearly as could be determined from examination of the bud development ard radial increases measured by the dendrometer, growth in the red pine stands started during the week of May 9-16. By May 16 all the plots had shown an increase in radial growth (Figure 31;)- During the period May 16-23, plots 80 and 190 showed a larger increase in radial growth than plot 120. By May 30, however, a radial growth trend developed that was to rennin the same throughout the course of the observations. Plot 80 constantly showed the most growth. Plot 120 was next highest in total growth; plot 190 showed the least total growth. Except for the month of June, the total monthly rainfall during the growing season of 1953 was above the monthly means for Crawford County, Michigan, as given in "Climate and Man" (19141). The year 1953 was a good year for tree growth in Crawford County because a greater supply of rainfall was available during the growing season than normally occurred. This in turn undoubtedly raised the level of available moisture in the soil. During the period of growth, four periods occurred during which the growth rates in plots 120 and 190 noticeably decreased. The first of these occurred during the week of June 6-13. Reference to Figures 20 and 21 will show that there was a marked decrease in rainfall for the period with a subsequent drop in soil moisture. Some low temperatures also prevailed during this period. Cumulative Radial Growth - Hundredths of an Inch .13 4 .12 a .11 4 .10 J .09 1 .08 " .07 " .06 a .05 i .01 ‘ 88 Plot 80 /\ /\ Plot 120 ./ V I *7 ‘U r T V V f T T f V T U I I 162330 6132027 13111825 1 8152229 May June July August Figure 3b. Cumulative Radial Growth Curves for 1953. Cumulative Radial Growth - Hundredths of an Inch .13 . 012 'l .11 4 e10 "‘ .09 i .08 ‘ .07 ‘ e06" .05 ' .03" .02‘ .01‘ 88 Plot 80 /\ /\ Plot 120 ./ V' I I V I I T I U I U l 16 23 30 6 13 20 27 h 11 18 25 1 8 15 22 29 May June July August Figure 3b. Cumulative Radial Growth Curves for 1953. 89 From July h-ll another decrease in the growth rate occurred in plots 120 and 190. This, too, was a period of low rainfall and the moisture content of the soil showed a decrease. A very marked decrease in growth occurred during the week of July 18-25 in plots 120 and 190. Plot 80 showed only a very slight decrease. The rainfall mich fell for the period occurred only on the first arxi last days of the period. The soil moisture trend for the period at the six inch depth shows a general rise. However, ‘ since the soil samples were collected soon as the rain had ceased on July 25, the soil moisture curve would show a general increase for the period. The best trend for the period is shown by the moisture curves for the 18 and 36 inch depths because the heavy rainfall which fell on the area during the morning of July 25 had not changed the soil moisture situation at those depths. The soil moisture trend for the period can be considered as a general decrease. On July 25 the soil moisture curves show the lowest soil moisture percentage recorded at the 18 inch depth for both plot 120 and 190. Also, at the 36 inch depth very low moisture percentages were recorded for these two plots. A shortage of soil moisture for the period evidently caused the decrease in the growth rate for the two plots. Plot 80, in which only a slight decrease in the growth rate occurred, showe an increase in soil moisture for the 6 and 18 inch depths for the period. At 36 inches the moisture content remained unchanged for this plot. From July 25 to August 1 only 0.06 of an inch of rain fell. The growth curve for the period shows that plots 120 and 80 increased r\'* r u r O -\ r . fl - L1 . A .— r~ «I, ._v \ .'n . . ' s -| U . ‘ C , c ' I O . fl ’ I (’ a f‘] . . N I | \ { f~~ -\ - . ,— . I _L . . \ . o -— (h J: r» ,l 4 \ . , r f A 1 A. 4 J ‘ ‘ I v I . -' . 5‘ . L - .4 —~ "I. ‘ .' _I- H A O .- w 1 \ ~ A 'r‘ ' I l’.‘ ‘ I . F v ‘ . \ . '. ‘ 1 v ‘v p .{ r ‘. . “r n P“ n 90 their growth rate. Plot 190 showed a recession. The moisture curves for the period show a genera decrease in soil moisture. At the six inch depth, plot 190 on August 1 had the lowest soil moisture content recorded at that depth fcr the red pine plots during the entire course of the study. The rainfall on July 25 of 1.03 inches must have been in sufficient quantity to satisfy the growth requirements of the trees on plots 120 and 80 so as to cause the trees to show an increase in growth for the week. Evidently the dry condition of the soil at the 18 and 36 inch depths in plot 190, in addition to the large nunber of trees per acre on this plot, had created a growth moisture requirement which could not be adequately supplied by the rainfall of July 25. On August 15 a recession occurred in all three plots. A similar recession was reported by Dils (1952). By August 22 all the plots showed a slight gain above the amount recorded for August 8. However, on August 29, plots 120 and 190 showed a recession of radial growth; plot 80 continued its trend of the previous week and showed additional radial growth. From August 8-29 there was a weekly de- crease in rainfall until by August 29 the soil moisture content of all the plots was nearly the same at all three depths. What caused the general growth recession in all plots on Auglnt 15 is not know. Neither is the reason known why plot 80 showed a radial growth increase at such a favorable rate on Augmt 29, while plots 120 and 190 receded fora second and third time respectively. Possibly the recessions} are associated with terminat ion of growth. -'x v ’ l T, 91 At the six inch depth, plot 190 was at the same moisture content as on August 1, when it receded in radial growth for the first time. Plot 80 for the period of August 22-29 showed a higher soil moisture content at the six inch depth than either plots 120 or 190. Possibly this slight moisture advantage coupled with the light rainfall for the period may have provided enough moisture for the riser roots to supply the growth requirements for the plot. It is also probable that some compensating factor, such as soil temperature or the amount of light received by the plot, may have aided plot 80 to show additional growth. The soil temperature curves show a distinct de- crease in the soil temperature on August 15, the date of the major recession, for all three plots. By August 29, plot 80 showed a distinct imrease in soil temperature at all three levels and was obviously warmer at all three soil depths than plots 120 and 190. Statistically, the radial growth for the entire season was not significant. Analysis of Variance of Radial Growth it h Source Degrees of Sum of Mean Square F F Freedom Squares Book Total h? 153,7h2 Between 2 11,519 5,759.5 1.822 3021 Within us 1h2,223 3,160.5 Examination of Table V will disclose the fact that the within error was so large as to make the analysis of variance insignificant. n. f\”\ [I 92 TABLE V-A. Radial Growth per Diameter Class per Plot. DOBOH. class Plot 80 Plot 120 Plot 190 (Inches) (Inches) 6 0.117 0.062 0.0141 7 0.122 0.088 0.072 8 0.131; 0.100 0.125 The radial growth data showed that for trees with a six inch diameter the rate of growth was 2.8 times faster three years after thinning from 190 to 80 basal area. From a basal area of 190 to 120 the rate for six inch trees was 1.5 times faster. For seven inch trees the comparable rates were 1.7 and 1.2 3 for eight inch trees the rate in reducing the basal area from 190 to 80 was 1.1. For the small six inch trees, reducing the basal area of the stand from 190 to 80 square feet resulted in almost tripling the growth rate. The dominant eight inch trees showed practically no increase. Within the same plot the larger diameter trees showed the largest growth rates. The less basal area the plots contained the greater was the rate of growth. On August 29, five increment cores were collected at random from dominant trees in each of the three plots. The analysis of variance for the 15 cores shows that there is a significant difference between the nunber of growth rings in the last inch for the cores collected. 93 Analysis of Variance for Increment Cores Source Degrees of Sum of Mean Square F F Freedom Squares Book Total 11; ' 6,666 Between 2 2,976 1,1188e0 110811'* 3088 Within 12 3.690 307 .5 t :=_-_=== The mean number of growth rings in the last inch for the cores collected from each of the three plots is as follow: Plot 80, 10.36 rings; plot 120, 12.78 rings; and plot 190, 13.70 rings. Growth was best in plot 80. Plot 190 slowed the least growth; plot 120 had an intermediate growth rate, but tended toward the growth rate of plot 80 (Figure 31.). By July 18 growth had practically ceased in plot 190. Growth continued in plot 80 until about August 8, there- after no important growth gain was made. In plot 80, on August 29, was still progressing. A heavy densiiy of stocking (large basal area) appears to reduce the length of the growing period for the stand. Forty-year old red pine stands at an average stocking of 80 square feet of basal area grow relatively satisfactorily on Grayling sand, gravelly phase. 93 Analysis of Variance for Increment Cores Source Degrees of Sun of Mean Square F F Freedom Squares Book Total 1).; ' 6, 666 Between 2 2,976 1,1488 e0 b.0811“ 3088 Within 12 3.690 307.5 g l:— Ea The mean number of growth rings in the last inch for the cores collected from each of the three plots is as follows: Plot 80, 10.36 rings; plot 120, 12.78 rings; and plot 190, 13.70 rings. Growth was best in plot 80. Plot 190 filmed the least growth; plot 120 had an intermediate growth rate, but tended toward the growth rate of plot 80 (Figure 31;). By July 18 mirth had practically ceased in plot 190. Growth continued in plot 80 until about August 8, there- after no important growth gain was made. In plot 80, on August 29, was still progressing. A heavy density of stocking (large basal area) appears to reduce the length of the growing period for the stand. Forty-year old red pine stands at an average stocking of 80 square feet of basal area grow relatively satisfactorily on Grayling sand, gravelly phase. " I l i '1 ‘A k K (A ‘ Pl q 0 \_ - .'." " x I ~ , - - F '- I ' f . . C . r . - . — r \ r I, | . r O I f' u - " \ (]\-/ f. - I A L {I 16' ,. , L‘ a. .V 0‘ .J‘ . -I _ J” a O n - \ i .L l L. .“ 7' V ‘ a) .1 or i _: [_. F‘ n \ I SIH‘MARY AND CONCLIBIONS A soil moisture study was made in a lib-«year old red pine (m resinosa Ait.) plantation during the winter, spring, 'and‘summer months of 1953. The plantation is located on the Higgins Lake State Forest in Crawford County, Michigan. The trees are grOwing on Grayling sand, gravelly phase; the area is relatively level and is geologically classed as an outwash plain. The soil moisture content was determined for the soil at the 6, 18, and 36 inch depths. The soil samples were collected at weekly intervals during the growing season from three red pine stands within the plantation vhich had basal areas of 190, 120, and 80 square feet, respectively, and from an adjacent open field. The soil moisture content for the soil samples was computed as a percent of oven-dry weight. Weekly resistance readings were taken using the Bouyoucos portable soil moisture bridge with Bouyoucos nylon electrical resistance units. The units had been interred since November, 1952. Measurements were taken from February 28 until August 29 , 1953. Previous to the month of May, measurements were taken at two-week intervals. In addition to soil moisture determinatiom, measurements and observations were made to detemine the depth of snow accumulation, rate of snow melting, precipitation, soil temperature, and radial growth of the red pins. 1. Snow accumulations were deeper in plot 80 than in plot 190; however, the rate of melting was greater in plot 80 than in plot 190. The snow cover had considerable influence on the supply of moisture \ r'o 'a r . ‘ C“ i, r r. a -/ .\ .- ". r 1 ‘\ \' Y . I I’l‘ 4 f r r o r i u I n '0 r '7 \ r 1 (w ‘I e I' “ \v' r r . r -f‘ 95 present in the plots; it remained longer in plot 190 than in the other two plots, 2. During the early spring months plot 190 had a consistantly higher soil moisture content at all three depths than did plots 120, 80, or the open field. This was due to the snow covere it contained and to the slow rate of melting. During the month of August, plot 190 had the lowest soil moisture cont ent at all three depths. 3. The rapid loss of snow cover in plot 80 resulted in an early decrease in the rate of increase of its soil moisture supply at the six inch depth. At the same time it Iroduced decreases in soil moisture content at the 18 and 36 inch depths. A gradual decrease in moisture content in plot 80 at the 36 inch depth was evident from March 26 until May 16; during this period and at this depth it had the lowest moisture content of any of the plots. 1;. Plot 80 had the highest moisture content at the six inch depth 82.1; percent of the weeks during the growing season; plot 120, 11.8 percent; ard plot 190, 5.8 percent. From July until September the usual trend among the plots at the 18 inch depth was a decrease in soil moisture with increasing basal area. 5. After June 20 the cpen field had the most soil moisture at the 36 inch depth. Soil moisture fluctuations were greatest in the open field. 1 6. Soil moisture fluctuations and differences between the plots were greatest from July 18 to August 22, they occurred at the six inch depth. , . kJ 96 7. There was a gradual decrease in soil moisture at all three depths from April 1 to August 29. On August 29 the soil moisture supply was extremely low at all three depths; all the plots and the cpen field were at a moisture content of approximately 2.7 percent at the six and 18 inch depths. At the 36 inch depth the average moisture content for all plots was approximately 2.0 percent. Cons irleriug the area as a whole, on August 29 the soil was at its most critical moisture level and tended to be nearly uniform throughout all the plots, including the cpen field; in addition, it was nearly uniform in moisture content at all three depths. 8. TABLE II-D. I-‘aximum and Minimum Soil Moisture Percentages (Percent of Oven-dry Weight). 6 inch depth 18 inch depth 36 inch depth P1015 Max. Date Min. Date Max. Date Min. Date Max. Date AMin. Date 190 10.80 3/31 2.57 8/29 7.h6 géga 2.35 7/25 7.70 3/31 1.66 8/29 12010.65 3/31 2.69 8/29 7.89 3/31 2.58 8/1 6.35 5/2 2.10 8/29 80 10.8h 5/2 2.92 8/29 6.91 3/31 2.73 8/29 5.83 3/26 2.22 8/29 Open 10.82 7/25 2.16 8/29 8.h0 5/2 2.22 8/29 8.7h 6/6 2.77 8/29 ‘_._ - . . . '_. - ._- --*O-‘—-.-.--o———m’-—-——._ u-o--- h. 4-m-~--_—uu—n—I 9. laboratory calibration curves for the nylon electrical resistance unit which will properly represent field conditions have not been developed for Grayling sand, gravelly phase. n\ 97 10. Empirical field-calibration curves have been developed for Grayling sand, gravelly phase. 11. Many nylon resistance units are needed to adequately sample the moisture content of an area. 12. Fewer units are needed as the depth to mich the units are interred is increased. 13. A separate empirical field-calibrated curve is needed for each depth to xhidi units are interred. 1h. The nylon electrical resistance units should be interred dry, preferably in the fall when Grayling sands are dry. 15. The nylon electrical resistance units require several months before they become stabilized to the soil conditions surrounding them. 16. Nylon electrical resistance units can respond quickly to sudden moisture changes under field conditions. 17. Perhaps the best use ofthe nylon electrical resistance unit in a sand soil is as an“ indicator of broad relative soil moisture conditiom rather than an actual moisture content. 18. Temperatm'es at all three depths in the cpen field were decidedly higier than the temperatures in any of the red pine plots. 19. From April 18 to June 20 an approximate rise in soil temperature of four degrees Fahrenheit per week occurred. 20. The curves at the 18 inch depth have nearly the same trend as those at the six inch depth. 21. After July I; the trend indicated for all the plots at all three depths was a general leveling of the temperature curves. 2r 1». c 98 22. Temperature fluctuations at the 36 inch depth are notably less then compared to those at the six and 18 inch depths for similar periods. 23. The recorded soil temperatures for the red pine plots at the six inch depth were never below 32°F. nor above 71°F.; at the 36 inch depth they were never below 3h°F. nor above 60.5'F. 214. In the open field the maximum and minimum temperatures were ~72'F. ard 36.5’F., respectively, for the 6 inch depth; at the 36 inch depth the mxinmm was 66.13”. and the minimm 38’F. 25. An approximation of the mean temperature for the period July 25 to August 29 at the 6, 18, and 36 inch depths would be 62, S9, and 58'F., respectively. 26. The general trend in order of decreasing soil temperatures at all three depths was plot 80, 120, and 190. 27. Radial growth began when the plots were at an approximate minimum temperature of h7.5 ’F. at the six inch depth; and a minimum temperature of h3°F. at the 36 imh depth. 28. During the first week radial growth occurred, plot 120 showed the least growth; this was not a characteristic trend for plot 120, and a corsequent inspection of the temperature graphs revealed the fact that the plot showed the lowest soil temperatures recorded at the 6 and 36 inch depths for that week. 29. During the week growth began the maximum and minimum air temperatures were 79'F. and 50°F., respectively; the mean temperature for the week was 614.1'F. No precipitation occurred during the week so it is assumed that the maximum amount of sunlight occurring for that week at that latitude was available fer photosynthesis. 30. Plot 80 produced.the best radial growth; plot 120 followed, and plot 190 showed the least radial growth. 31. There were three periods previous to August 15 when plots 120 and 190 showed greatly reduced growth rates. This was attributed to a lack of sufficient soil moisture in the plots. 32. Radial growth practically ceased in plot 190 by July 25. 33. A general radial growth recession occurred in all plots on August 15; there was a slight drop in soil temperature in the plate on that date. 31;. On August 29 radial growth receded again in plots 120 and 190; plot 80 continued to add radial growth at a comparatively rapid rate. Plot 80 showed a definite increase in.soil temperatures on that date, which were larger than the soil temperature increases shown for plots 120 and 190. 35. The radial growth data showed that thinning from a basal area of 190 square feet to 80 square feet the growth rate almost tripled for 6 inch d.b.h. trees; for 8 inch d.b.h. trees the increase was very slight. 36. The growth rate for dominant trees increases only slightly when thinnings are made. 37.‘Within the same plots, the dominant trees showed the best growth. 38. Reducing the density of’the stand increased the total radial growth rate for the stand. 1‘. . - {\ 1"“ ‘ ‘ -“‘ r“ ' ‘ “ ' ‘ “ F A x K v ‘ " ‘ _ O u '— - ,7 ’ ‘ r y A \ . F . -- u. ,7 7 .— ,. ' , r I W . . I ‘ I O f- , w - - 1 7‘ l _ A J - . J o 1 s - ’ 7 P f (- ‘ u - V ‘ r I. - v ‘ If. .j, " O '_ 1 " ‘ ." ’ f" '— x e , 1‘ (I . , v I Y . . H ‘ . s 1 O \ u . r 3 y . L . W‘ . ,2 . , A ‘ 7 . \ ,- . ' . O O O - . z - r1. _ . . 0'. J . 7 \ . t 'N . \ ~. \. - . . | O . ‘ \ . .. . \ ° \ g V '. r' g . a I . a ‘ 1 ° .1 ‘ ‘ . ' r» - " VI' - 100 LITERATURE CITED Albert. 1915. Ungllnstiger Einfluss einer an grossen Stemahl suf den theserhaushalt winger Kiefernbdden. Zeitschr. f. Font-g. Jagwesen, fl: 2111-2148. ° . 1925. Der mldbauliche Wort dor Dunensande, souls der Sandblden in ellgemeinen. Zeitschr. f. Forst-g. Jagdwesen, 3: 129-139. bend, John L. 19112. Infiltration as affected by the forest floor. Proc. 95 3.313 Soil Sci. §g_c_. g_f_ Amen, 191:1. é: 1.30-4.35. 387913, In. Do 19,480 8011 Engine. 1111 * 398 pp. John Wiley and 30m, NEW Im'ko Bounces, George J., and A. 8. Mick. 19140. in electrical resistance lethod for the continuous leasurement of soil moisture under fa.“ condition. Michigan 53‘ he E‘s-.‘., I'd. Bile 172. 3 PP- Bowoucos, George J. 191.9. Nylon electrical resistance unit for continuum measurement of soil moisture in the field. Soil §_c_i;., 67: 319-330. Brigg, Lynn J. 1897. The mechanics of soil moisture. U. S. “a. 930’ Pg. 2; $011., 1111-. l2. 2“. PP. Briggs, Lynn J., and H. L. Shants. 1912. The wilting coefficient for different plants and its indirect deter-instion. U. S. DOE. mo, Bureau 2!. P131115 11‘1th, 231.. £29.. 83 pp. Cameron, Frank 1., and Francis E. Gallagher. 1908. Moisture content mi physical condition of soih. U. S. Dept. 53., Bueau 2!- 30118, 22;. 59’s 70 pp. Carlton, Paul 3., n. J. Belcher, 2. a. Cuykendell, and H. 3. Seek. 1953. Modifications amd tests of radioactive probes for measuring soil moisture and density. Cornell University Technical. Developed. m No. 191;. 13 pp. Crsib, Ian J. 1929. Sons aspects of soil moisture in the forest. Isle Univ. School 2; Forest , £111.. _25. 62 pp. Dils, Robert E. and Maurice V. Day. 1952. The effect of pre- cipitation and temperature upon the radial growth of red pine. BL! American Midland Naturalist fl: 730-731;. ,1 (N y. e o . .— . - I - ._ . ”_._. . ,. I K ~__ _-_—— C O . _._.-- ~ . . p Q 9 \ , ._ -m - n x . _.g—.. V . I ;‘ ”H. -m. . Q , Q e v F- o P Q . y" 101 lbemyer, Ernst. 1889. Einfluss des Waldes und der Bestandes dichte auf die Bodenfeuchtigkeit und auf die Sicheruasserlenge. L115. Font-3. Jag-Zeitrmg, gs: 1'13. Hubbert, 14. King. 19140. The theory of ground-water notion. Jour. GOOle, he! 785-9hhe Keen, B. A” and J. R. H. Coutts. 1928. '8er value" soil properties: A stuck of the significance of certain soil constants. Jour. Age £33" 183 7140.765. Kittredge, Joseph. 191.8. Forest Influences. I 4' 391; pp. Hearse-Hill Bock Conpew, Em, New Iork. hssen, Icon, Howard H. Dull, and Bernard hank. 1952. Sons plant-soilmter relations in watershed aanagenent. U. S. jDe. 53., Div. of Forest Influences, Pores—_t _S___ervice, NJ'EQ! _I-a-tPP- lute, Harold J., and Robert 1’. Chandler, Jr. 191.6. Forest Soils. xi + 51!; pp. John Wiley and Sons, 1110., new !ork. Heinser, Occu- E. 1923. Outline of ground-eater Mdrology. Us 3e D. e Interior. G001. Survey. “term 2.322 «TIPP- Miller, C. I. and L. H. Turk. 19,43. Fundamentals of Soil Science. :1 ‘0 1:62 pp. John Uileyand andmsg ,5)?” New MM, Ea H. m He We M10 1953. “Mon 0: for tip“ of electrical resistance instruments for measuring soil noistm‘e. Southern For. Eg___ Sta. Occasional m_ 128. 158 pp. Peter, F. U. 1922. The classification of soil noisture. Soil §£_i_. Q: hB-Sh. Rater, Oran. 1937. Hater utilisation by trees, with special reference to the economic forest species of the North Tm. ZOBOe no so DOEe Age, m8¢e Ea me 97 pp. Balaton, a. A. 1953. Effect of stand density upon red pine height growth on poor site in northern lower Michigan. Paper resented Mich. Acad. Sci., Arts, and Letters. April 10, 1953. Reinhart, I. O. 1953. Installation and field calibration of fiberglass soil noisture units. Southem Egg. Q. Sta. Occasional Lam _13_8_. h8 pp. r ‘ -— - I l . C O“ . ..‘ . x ' ' g. r . I r_ , z. I. r I .o ‘ . «In I \ \ ‘ . r— .r ‘ . r ‘ . 1‘ . . t I" e F C- c r”. ' z. 0 -.--' . ...__. O . I c' ' w _w- -— - e. . . O ,. . . O “ ' 7 r ." '— - . t“ _.. '— \‘—_- ' — ‘ I. D . .- "o—v—h F... , n t' ' K * + ’ r O ”“ - ,- . z . C . . - . . I __. .‘. -~ , . Q . . ' . ' . + ‘ ‘ C _,i__ , ' . , ‘ I I . ' . l \ . D _“ - O \ I" I O . t _ ."' -v\ " o- ‘ "—_— ‘ - .—.a—. - . _. O . . . . F' ‘ r I h v . . O _. - r‘ . I I . ~ . v ' . - ' -- 0‘ ‘ ( ...’ O_ ' . . I .. .- . . J . . i r . e‘ F'- .__“° ‘ 102 Veatch, J. 0., L. R. Schoennan, z. 0. Foster, and F. R. Leah. 1927. ‘Soil survey of Crawford County, Michigan. 1!. S. D"! Bureau ______o_f_ Chenistg___ and §__,oils §____eries 4:172 Viehneyer, P. J. and L. H. Bendrickson. 1927. Soil noisture coalitions in relation to plant growth. Plant Mic . 2! 71-82, 11111:. e 1931e The noisture eqtflva'fén‘tw as a neasure of the Held capacity of soils. Soil Sci., 33: 181-193. Hhitney, Hilton, Frank D. Gardner, and lumen J. Brigg. 1897. An electrical Mind of determining th. noisture cm of mbla 3011.0 Us Se DORE. Alfie, DimiOE 2.; $011.. PE}... ée 26 pp. Iearbook of Agriculture. 191:1. Climate and a. House Deon-eat no. 27, 77th Coupons-TE? 55.1.11, 0. s. Goren-ent Printing Office. I. h..- A. B. C. D. IPPDIDII Data recorded within or collected fro: the red pine plantation designated for thinning studies by the U. 8. Forest Service at Higgins Lake State Forest, Michigan. Data. recorded at U. 3. Weather Bureau cooperative weather station at Higgins Lake, Michigan. Data recorded for the laba-atory calibration experinents with the . Bomucce nylon electrical resistance unit. Plot ding-an. 10h .APPENDIX.L TABLE I. Cumulative weekly rainfall, 1953. Dates (inclusive) Rainfall (Ihches) may 2-9 0.03 10-16 0.37 17-23 I 1.1.5 21.30 1.52 May 3l-June 6 1.65 June 7-13 0.19 11-20 o.h8 21-27 0.51 June 28.-Ju1y h 2.6).; July 5-11 0.31: 12-18 ' 0.95 19-25 0.07 July 26-August 1 0.08 August 2-8 1.57 9-15 0.78 16~22 0.31. 23—29 0.17 Total 13 .15 e ".'c r‘ ‘ .— (‘fi \ ’- ;. ~- \' r r“ 0.... k - .L r r f _ _ p.. x 105 TABLE 112A. Soil moisture averages from.soil samples at the 6 inch depth expressed as percent of oven-dry weight. Date Collected Plot 80 Plot 120 Plot 190 Open 21.18 February 28 7.56 6.82‘ 8.19 .... March 26 8.99 9.21 9.77 .... 31 8.82 10.65 10.80 8.83 April 18 9.31 9.56 9.13 10.39 may 2 10.81 10.33 8.95 10.91 9 7.86 7.17 6.19 7.80 16 7.66 , 6.29 5.61 7.85 23 8.77 ‘ 7.00 6.77 7.71 30 8.72" 8.82 9.13 10.06 June 6 9.92 8.62 8.88. 10.53 13 7.13 6.80 6.16 6.85 20 5.51 5.18 1.17 5.72 27 5.70 1.65 1.11 6.53 July 1 8.00 7.20 7.31 7.61 11 5.10 1.25 3.88 3.73 18 ' 7.29 6.19 5.76 8.11 25 7.57 8.98 6.58 10.77 August 1 11.141 3 .01 2 .65 3 .11 ' 8 8.15 7.08 . 5.11 10.82- 15 6.35 6.61 1.12 10.58 22 1.86 3.57 3.12 3.80 29 2.92 2.69 2.57 2.16 Total 162.07 151.31' 139.95 151.56 O r f [- r ’ r ,. F \ _‘ - .00. O O o i t ’ \x q... l\-. . 0 l; r‘ ‘~‘ 0 r. . . s 0 L; 1 r, \ r l t . . l\ g Q -. O r r f r '7‘ " i r I" . 5 e \\l c S 1 , r \ I r“ \. a I‘ O V .\ a r v\ A \ \\ x _ I \ \ . . -1. . I J r ' K \ ‘ ’ ~~ '; ll‘ Y1. o\. Y . g.) f‘ " I‘ .— \‘ . r K . .3 I Y. K - ‘ 2’ \ \ . r e S 0 Q Try ~ \ \ \ ' \ P! p..- ‘ ‘ In I g e I , ~.. ‘ 0.. Yrs 1‘. ' ‘ 5 . ...fi 11“.... - expressed as percent of oven-dry weight. 106 TABLE II-B. Soil moisture averages from soil samples at the 18 inch depth Date Collected Plot 80 Plot 120 Plot 190 Open Field February 28 5.09 5.57 7.10 .... March 26 6.66 6.91 7.35 .... 31 6.91 7.89 8.37 5.79 April 18 6.12 6.70 7.16 5.70 May 2 6.67 7.19 7.16 8.10 9 5.68 ~ 5.37 5.70 1.92 16 5.17 1.53 1.91 5.76 23 5.55 6.23 5.69 6.61 30 6.75 7.11 7.17 7.55 June 6 6.10 7.62 7.15 6.27 13 5.22 5.27 5.33 1.13 20 1.11 1.51 5.36 1.71 27 1.17 3.71 3.31 3.90 July 1 5.97 5.61 5.75 1.99 11 1.35 1.25 3.95 3.55 18 3.32 3.62 3.15 3.76 25 5.19 2.72 2.35 3.511 August 1 3.05 2.58 2.57 2.52 8 3.16 3.21 2.62 . 2.90 15 3.33 3.22 2.86 6.18 22 3.30 2.90 2.91 5.19 29 2.73 2.85 2.18 2.22 Total 109.8 110.0 111.0 99.52 6 0a.. O o I \ C \ O ,\ x O ’ 1 O ‘7‘ \ ‘ e \ O O ‘ \ O .. .\ \. ‘ - ‘ O O \ . O \ e O \ x O 0 ' J /) . _ . x \ r ,. \ \ .. \ t. \ .. - - -r' ‘ \ 5 a. \ 107 TABLE II-C. Soil moisture averages from soil samples at the 36 inch depth expressed as percent of oven-dry weight. Date Collected Plot 80 Plot 120 Plot 190 Open Field February 28 1.81 1.71 7.39 . . . . March 26 5.83 1.93 7.19 .... 31 5.08 5.28 7.70 6.17 April 18 1.79 6.12 5.19 6.21 May 2 1.71 6.35 6.67 7.19 9 1.61 1.87 5.23 5.77 16 1.17 3.81 1.59 3.5h 23 1.69 1.10 1.57 1.15 30 1.57 1.87 1.61 7.12 June 6 5.18 5.68 1.13 8.71 13 1.31 5.68 5.70 1.65 20 3.61 3.30 1.99 1.17 27 3.19 3.56 3.97 7.8h July 1 1.20 3.19 5.35 8.20 ° 11 3.91 3.57 3.51 1.21 18 3.09 2.85 3.15 5.38 25 3.13 2.15 2.39 1.30 August 1 2.61 2.31 2.72 2.90 8 3.09 2.90 2.27 3.81 15 2.73 3.00 1.88 1.02 22 2.30 2.25 1.69 1.11 29 2.22 2.10 1.66 2.77 Total 87.3 88.5 96.9 106.27 I \ F n ' ¥ . — \ 1‘ - Tr r, \- ' r - . ' r} A r ‘ ‘ .00. ~" "r . r ' fl . e '., - (1\ ~: 7 N .. . on \ I o \‘ =1 N ‘.\ 'r- ';r.‘ “‘.I F r ‘ (”15. Y".\ ‘:e\ '<.' Q 7:. :3 V -' ”U 7 ' * 1‘ '-: WI \7 Es' \ O ‘ " ‘ . A \~ \ 1 \ s“ S' e r . I Y ‘ ‘1 s I ‘ \ I “ ' \ l . [I O r. \ \ \ 7 \ ‘ I . , e -[e‘ge ”I K . f'l ' ~ I\ -. Y_r:. U \‘\. .\ A J I ’ ‘ . ‘ In .7 x .1. '\ I ‘(.K- Y: A x- ‘ I - .1 A f ..\e 1_.. .\ j\" 1‘ "fl ' r ‘ v. _ J. . \ . .\ ' .\ 0‘ rr f-| ~ A ‘ ‘ 1F. ‘ ’r' r . .- f\‘ ' r T I‘ ' ‘ fr ‘- . \,_ s Qw'; ‘Q I I. I \v". A " I. ‘ o o "" -- .\ N —. r‘l' (N | 77 ' r‘: r ‘ ‘ ‘ ‘ _.. "of ‘ ' -‘. C‘" 1.: G \‘ r. ‘ | n \ 1? ‘er I. (‘0'? . a \ \, ‘ ~ YT. r P. e - t'fi. F"' 108 TABLE IIIeA. Bouyoucos nylon.block resistance averages at the 6 inch depth. Date Recorded Plot 80 Plot 120 Plot 190 Open Field (0883) February 28 16,000 90,500 23,000 15,000 March 26 18,000 15,000 22,000 39,000 31 17,000 11,000 21,000 16,000 April 18 11,500 31,000 18,000 13,500 may 2 11,000 30,000 19,000 16,000 9 17,000 11,000 10,000 18,000 16 29,000 115,000 190,000 18,000 23 19,000 76,000 16,000 18,000 30 16,000 50,000 21,000 12,500 June 6 11,500 29,000 23,000 11,000 13 20,500 98,000 69,000 21,000 20 51,000 310,000 360,000 66,000 27 98,000 570,000 115,000 72,000 July It 1153000 669000 359000 311,000 11 72,000 310,000 310,000 210,000 18 150,000 310,000 21,000 23,000 25 100,000 260,000 23,000 26,500 August 1 160,000 320,000 320,000 180,000 8 180,000 160,000 15,000 16,000 15 38.000 1311.000 55.000 28.000 22 78.000 370.000 270,000 36,000 29 260,000 360,000 110,000 190,000 d I? n\. \.1 109 TABIE III-B. Bouyoucos nylon block resistance averages at the 18 inch depth. Date Recorded Plot 80 Plot 120 Plot 190 Open Field (OHMS) February 28 13,000 22,000 11,000 16, 000 March 26 13,000 19,000 11,000 25,000 31 12,000 20,000 13,00012,500 April 18 11,500 18,000 111,500 12,500 May 2 11,500 19,000 16,000 13,000 9 12,000 20,000 18,000 11,000 16 18,000 12,000 81,000 13,000 23 13,000 10,000 61,000 10,500 30 13,000 11,000 61,000 9,200 June 6 11,500 28,000 30,000 9,100 13 13,000 31,000 37,000 8, 600 20 36,000 110,000 220,000 15,000 27 160,000 370,000 350,000 29,000 July 1 27,000 300,000 66, 000 21,000 11 52,000 26,000 210,000 26,000 18 310,000 580,000 180,000 320,000 25 330,000 510.000 130.000 390.000 August 1 300,000 1,000,000 350,000 110, 000 8 390,000 110,000 290,000 160,000 15 111,000 311,000 310.000 91,000 22 290,000 510,000 100,000 250,000 29 130,000 610,000 350,000 100,000 Ni ~x\., r rll. _r r, '\ I\ r, x V v r. 7’ 0s Ox Ix r F o ox v\ I r _ x '. pk \ 109 TABLE III-B. Bouyoucos nylon block resistance averages at the 18 inch depth. Date Recorded Plot 80 Plot 120 Plot 190 Open Field (OHMS) February 28 13,000 22,000 11,000 16,000 March 26 13,000 19,000 11,000 25,000 31 12,000 20,000 13,000 12,500 April 18 11,500 18,000 11,500 12,500 may 2 11,500 19,000 16,000 13,000 9 12,000 20,000 18,000 11,000 16 18,000 12,000 81,000 13,000 23 13,000 10,000 61,000 10,500 30 13,000 11,000 61,000 9,200 June 6 11,500 28,000 30,000 9,100 13 13,000 31,000 37,000 8,600 20 36,000 110,000 220,000 15,000 27 160,000 370,000 350,000 29,000 July 1 27,000 300,000 66,000 21,000 11 52,000 26,000 210,000 26,000 18 310,000 580,000 180,000 320,000 25 330,000 510,000 130,000 390,000 August 1 300,000 1,000,000 350,000 110,000 8 390,000 110,000 290,000 160,000 15 1h1,000 3hh9000 310,000 9h9000 22 290,000 510,000 100,000 250,000 29 130,000 610,000 350, 000 100,000 h fl P. r. A \ a“ . I DA FL 7|. p n I 03 J . a . A .\ ri A ‘.I, V‘ FLA ~ \ I n)». rL as n... . a C. .7 . an) . . run . Z enkaLrinbv... Jr _ rJr rfir r .1\ «.‘.. r171 1,. fx 1 a . _ . ax . run . 1\ _r n a r.. I H .\ '\ ox I 1 C t O. l . t 7. ox 0‘ ox Q vx 9‘ Os Q l\ 9‘ .. r. _ . . r r . r ... h s , I r- _ F ‘r a. A, 5 A F, . e I I a. . 1 . \ 1 7r. Cr . 1 n .010. r o c _ . 1 \1 x x- _ . F 7t. 7?. x Z r7.r ,\ - v 1 F.. a I, ‘1 lurL . I n _ 1 - x P I t t 1 K Q 0.. .1 ! .‘. Q Os 1 C. Q 1 t I\ -\ l i K Os . _ a , r P: r r a- .- r x _, p a . b. r p . r ht _ 4 A P , n. I P a- e H, r n . n _ n - 7 E n i .l 3k r1... . - r \ x 1 a, \ - n. .1 . .111 \ -- - x C . . t t l t u t t p ox Q Q Q i Q I Q Q C t I Is 1 r f r . f flu f h .1 r r: _ A F , n: F P l _ n .1 1 , e , a n» 7 P . nx Pi n r 1 I 7 - a 7.. Ft. 7. r 1 F r! _ _ r1 r: r u n» In \ n n . . a . x 7 a . o. 1 { ox l C l f. 7 ex 1 I t 0‘ .. { ax l\ I l K Os v 1 r n\\. C. \ .. . _ a.) - a .1 _ \ r . r. 7 Wu .7. .. r r - r: _ r n- f\ 1: A a u n f ./ bk P1 . 110 TABLE III—C. Bouyoucos nylon block resistance averages at the 36 inch depth. Date Recorded Plot 80 Plot 120 Plot 190 Open Field (OPUS) February 28 13,000 12,000 10,000 13,000 March 26 12,000 10,500 8,500 23,000 31 12,000 15,000 8,000 13,500 April 18 12,000 11,000 8,500 13,000 May 2 12,000 12,000 8,500 11,000 9 11,500 11,000 8,200 15,000 16 12,500 12,500 10,000 15,000 23 11,500 12,500 10,000 13,500 30 13,000 13,000 12,000 15,000 June 6 11,500 13,000 12,500 16,000 13 11,500 12,000 9,100 15,000 20 13,000 15,000 16,000 19,000 27 139500 3&9000 51,000 19,000 Ju1y 1 12,000 36,000 76,000 19,000, 11 13,000 39,000 70,000 19,500 18 11,500 110,500 160,000 23,000 a 25 16,000 350,000 380,000 27,000 August 1 16,000 210,000 310,000 28,000 8 21,000 390,000 510,000 38,000 15 21,000 390,000 100,000 10,000 22- 26,000 390,000 190,000 16,000 29 32,000 270,000 370,000 52,000 TABLE IV-A. Soil temperature at the 6 inch depth. L” r Date Recorded Plot 80 P1ot 120 Plot 190 Open Field (Degrees Fahrenheit) February 28 32 00.0 coo. coo. March 26 3205 .ooo one. o... 31 3605 33-0 3205 3605 April 18 33.5 3,400 3205 3700 May 2 10.5 3905 39 00 11.5 9 51.0 1.1900 149.5 66 .0 16 50.0 16.0 17.0 58.0 23 18.0 19.0 16.5 56.0 30 50 .0 51.0 15 .0 52 .0 June 6 55.0 51.0 5205 5900 13 57 .5 55 .5 514-5 61.0 20 71.0 68.5 66.0 70.0 27 60.0 60.5 58.5 66.0 July 1 61.5 60.5 58.0 69.5 11 62.0 61.0 57.5 68.0 18 66.0 66.0 63.0 72.0 25 59.5 59.0 58.0 61.5 August 1 62.5 62.0 6205 68 .0 8 62.0 61.0 60.0 62.0 15 61.0 60.5 60.0 61.5 22 61.5 60.5 60.5 67.5 29 65.5 - 63.0 62.5 69.5 {.01. . r1 :1 .\ \ 1.1 f. \r I 1.\. «x. (n. r.. I n \ I 1 11 VI rJ . k I n . o 1.1 1. 1. f1... 1 \ \ x C... \ 1 1 r 1... r1 ..\ ,7 .1 e u o o o u o e o 9 u a . .. . r. a... 1 ._ .. r. . n I . 1 1- . u \ . \ \ . o . 1 7. . - , . ,. \ ..x I . a e a o O c o l o I o . N e o - . _., r.. x .1, .. n. . . 3. o . 1 x, .1 _- \ \ \ o . n. 1,.1 \\. 1- ax. \ \ , 1 n. V. . . o n o o c n o o o o a a; o . . x x. ,c f x... l. ...-1 F1. fl w l.— C O 1 \. \ x I \ Y‘ .\ u o - x s. x... S .. . . Q o 9 0 o c o a O o c o u .. . . .u . .. p L . 1. 1‘ . 141, ms. 0.. F\. F. \ \\ c 0 ~,.\». \ \ 11 O O . r. x \ .. C. v e - 1r \ \ o a H .1 .‘.—.‘-- ‘- _m 1 o _. TABLE IV-B. Soil temperature at the 18 inch depth. Date Recorded Plot 80 Plot 120 Plot 190 Open Field (Degrees Fahrenheit) June 20 66 61 59 67 27 ' 53 56 51 62 July ’4 5705 58 S6 6’4 11 59 58.5 56 6S 18 63 62 61 68 25 58 S? S6 61 August 1 60 59 59 66 8 60 60 58 66 15 59 59 58 61 22 58.5 59 57 61 29 62 61 59.5 69.5 _. . . FL 1... +. r 1 r1 rl 0 1.) n} . \ x. \ \ \ .1. . u e x \ \ Fl- 1 V1 I Pl 0 \. \ r»; \ Y e \ \ \ \ \ \. x x \ 1\. v \ \ e _ . TABLE IV—C. Soil temperature at the 36 inch depth. Date Recorded Plot 80 Plot 120 Plot 190 Open Field (Degrees Fahrenheit) February 28 3:: e e e e o 0 ”31.011 26 3,4. .5 e e e e . e 31 38 31 31.5 38 April 18 36 35 05 3,405 38 M87'2 38.5 38.5 37.5 11 9 13 13 13 18 16 15 13 13 19 23 15 15 11 51 30 19 18 16 53 June 6 50 18 17 .5 56 .5 13 52.5 51.5 19.5 58 20 58 55 55 66 27 56 55 53-5 62 July 1 58 56-5 55 61 11 57.5 57 51.5 63-5 18 58 .5 58 55 65 25 58.5 59 56 61.5 August 1 59 58.5 58.5 65.5 8 59 59 57 65 15 58 58 57 63.5 22 58 57.5 57 63.5 29 60.5 59.5 57.5 65-5 I r AA r45 \ rr\ . . ... xri. r . — \ . «K.— ., _ ._ . a I I e, - x C. \ O . H C ~ \ . . \_1‘\ O c I.‘ I I x. I, - u . . _. T 7 - \, O C I I x» \r l . FA. , rL‘ y. r . x . r x I S S J I Fr 2. ._u .L T7 F”, a _ I a, I Q. h; H n\_ r. _ .. H 7 . r V x f \7 I T I. r: ‘f o b O O O u \. :\\.. k f \ T... _ r . .v‘ - I I I O O A. e e I ._ . X . r r L- \ v. ruV. T O 0 § O I O x. H, 6 e g. . \ \ x. \ \. \ \ \ \ \ \r \x \- C4 , . :k a. 1 e . o o I O I O c N a e 7.. ._ ,__ TABIE V. Average radial growth gains and losses as computed from the dendrometer recordings. Date Recorded Plot 80 Plot 120 Plot 190 (Inches) 23 +0.0058 +0.0053 +o.ooh3 ‘ 30 40.0113 +0.0IOh +0.0066 13 40.0061; 40.0021 +0.0011 20 40.0088 40.0097 40.0062 27 40.0093 90.00711 +0.0060 July I. +0.01o6 +0.0119 +o.oo93 11 40.0058 40.0010 40.0028 18 +0.0193 +0.0188 40.0119 25 40.0016 +0.0007 40.0006 August 1 40.0073 40.0038 -0.0009 40.0085 40.0071; 40.0051; 15 -0.0080 -0.0083 -0.0076 22 40.0128 40.0099 +O.(I)89 29 40.0073 -0.(D31 -0.0028 Total radial growth 40.1221 +0.0886 40.0615 r... X. «.‘.. . I. .1 S a n) S K fix 9. . Av _ . ..._ . ~ .1 4 O : Cc . mg I + . O r. x ._ + M a O a. \ rr g... APPENDIX B 115 TABLE VI. Air temperatures and rainfall as recorded at the U. S. ‘Weather Bureau Cooperative Station at Higgins Lake, MiChigan o 1953 o May June July August Date Rainfall Rainfall Rainfall Rainfall ‘F Inches 'F Inches ‘F Inches ’F Inches 1 39 0.33 65 0.02 85 2.35 68 T 2 16 0.11 38 0 75 0 69 0.22 3 17 0.01 69 0 66 0 70 0 1 60 .... 70 0.82 76 0 65 0.72 5 70‘ 0 71 0.12 .. 0.21 62 T 6 68 0 52 0.07 .. .... 70 0 7 68 0 62 0.0 o o o o o 0 6h 0 8 70 T 75 0.08 .. .... 62 0.67 9 79 O 62 T . . . . . . 68 0 10 71 0 73 0 71 0 79 0 11 71 0 70 0 78 0 79 0 12 57 0.23 73 o o o o 82 O 72 0063 13 50 0 72 0 82 0 67 0 11 51 0 73 T 77 0 83 0-06 15 61 0 61 0 79 0 71 0 16 62 0 65 0.36 78 0 68 0 17 53 0.15 72 0.01 81 0 71 0.01 18 63 1.28 71 0.01 78 0.82 75 0 19 61 0.06 78 0 78 0 75 0 20 61 0 82 0 78 0 80 0 21 53 0.07 79 0 80 0 63 0.20 22 51 0.02 75 .... 69 0.07 79 0 23 6S 0 65 0 S6 0 80 0 21 , 59 0 68 0 61 0 78 0 25 52 1.32 73 0.13 71 1.03 75 0.28 26 19 0.01 77 0 79 T 80 0 27 60 0 75 0 71 0 85 0 28 60 O 72 0.35 70 0.06 85 0 29 59 0.26 73 0 76 0 85 0 30 52 0.09 73 0.38 71 0 79 T 31 59 0.0).). 0 O o o o 0 79 0 78 0011‘» Total 1.07 2.71 14.57 2.93 [J I fix.) I .r r1 r1 r1. FL 7, F; I .1.“ .1 _.. .7 __ a.» a «x a 1,\ .77; ax, ..\1 1k . 7 c \4. _\ r e I t \ ,- \. _\l 1 r. a A 1 k v .1 x V 7 1 .( r1 :1 . ..\\ x \ ”c\ ..\n . \ \ \ \ \ \ I \ x a \ F“ r1 7. 1 A 1 \ri I A \r_ 7 n\ r F 1 «\ .7 I r r. e o . c e p o o 9 v u o I o r. 0 r7 , A. . e \ T. at n l- \ , - \\ \ .1 7 I \ \ \ ,. ,x 1 ‘7 \ \ ..\. h\ . V n - r,\ 0 r1, . r J. . . 1\ \ rJ r x . z .A T. . ( A . l \. o . o o o o o o u . w o o a o 9 Q o 7 c 1 ._ O 1 x 1 7 T n \ . - 4 \ -- . 1 n , . . r. - n . o o - \u - \t .,\q \ \ y \ n \\ n I a o \ , .\- fl \ ! \ 7 I 0 o I o u . o I O I x. u . o r \, . D C O I 1‘ v a ‘ \ x \ . \ \ \ x- \ .21 x \ e I» x n 5 \ N ‘\ x xx x. r . n. A . a .l, r . 1 o o o 1 o O t . o my .1. \ I Q, F A.\ ,N\ Y N \ K .. \r a I l P k e . .\ I 7 a... 1“... 116 AF?ENDIX.C Table VII. Laboratory Calibration -- Using Stratified Nylon Electrical Resistance Uhits in a Sand —- Container Open Only at the Top. Depth From.Top of Container - Inches Date 8011 6 5 1 3 2 1 bkdsture Percent Ohms at 72°F. March 7 130 50 50 50 75 125 23.0 8 70 60 60 70 120 230 21.8 9 60 70 . 70 90 180 250 20.0 10 70 90 110 120 220 275 18.7 11 8o 90 120 130 225 270 17.7 12 80 90 125 130 220 260 16.7 13 80 90 130 190 225 260 15.5 11 90 100 130 110 230 260 11.5 15 90 90 125 110 230 250 13.1 16 90 90 125 110 210 250 12.3 17 90 90 120 130 220 210 11.3 18 9o 90 120 125 200 230 10.1 19 90 90 110 125 200 225 9.1 20 100 80 110 110 125 190 8.1 22 110 80 90 100 150 175 5.7 23 120 90 90 100 150 210 1.6 25 125 100 110 110 160 160 3.9 27 130 110 110 120 170 1,000 3.1 28 110 110 110 125 190 11,300 3.2 29 110 110 110 120 190 9,500 3.0 30 110 110" 110 120 225 11,100 2.9 April 1 110 110 120 125 280 21,500 2.6 2 150 110 120 130 360 16,000 2.5 3 150 110 125 110 500 130,000 2.3 1 150 120 130 160 1,050 350,000 2.2 5 160 125 110 175 1,950 660,000 2.1 6 160 125 110 180 1,500 720,000 2.0 7 160 125 150 200 12,000 800,000 1.9 8 160 125 150 230 23,000 1,100,000 1.8 10 175 150 175 375 130,000 1,800,000 1.7 12 200 175 220 775 100,000 ......... 1.6 11‘. 225 200 280 2,225 500,000 00.00.00. 10’... 15 260 220 3110 h,350 1,100,000 0.00.0000 1.3 17 350 325 600 12,500 ......... ......... 1.1 19 525 575 1,350 22,500 ......... .. ..... .. 1.0 I5 I‘ ,’I , " I" I' ' r‘ ‘ v- .1 - . F :——T \ }._.‘ r '1 _ .'. ‘_ . I - k, 117 TABLE'VIII. Laboratory Calibration -- Using Stratified NylonmEIectrical Resistance Units in a Sand -- Container Open at lop and With Perforated Bottom. Date Depth From Top of Container - Inches Soil 1 2 3 h 5 6 Moisture Percent Ohms at 7S’Fo June 1h 150 80 ‘ 10 25 50 50 22.7 15 170 125 50 25 30 10 21.1 16 190 150 75 6O 60 50 18.1 17 210 175 100 80 90 90 16.2 18 225 175 120 100 100 100 lh.h 19 225 175 120 110 130 100 12.7 21 225 190 110 130 110 130 11.h 23 225 210 160 150 160 150 9.2 2h 225 220 170 170 175 160 8.1 25 230 225 175 175 175 170 7-5 26 250 250 180 175 . 180 175 6.7 28 275 290 210 190 200 200 5.h 30 310 350 260 250 250 260 1.2 July 2 550 . 170 320 310 320 330 3.0 3 1.110 ‘ S80 360 350 375 h7S 2.3 5 6,300 1,050 180 175 580 1,650 1.7 9,200 1,200 510 500 650 2,250 1.6 6 30,000 2,700 775 700 1,250 9,000 1.1 8 300,000 21,000 2,900 2,300 11,700 300,000 0.8 9 910,000 11,000 7,200 1,750 30,500 780,000 0.7 ,r. ‘ r / I F) I F fl F F» rl F1. \. I r. r \ I u v \ . r1 f. A 117 TABLE VIII. laboratory Calibration -- Using Stratified Nylon Electrical Resistance Units in a Sand -- Container Open at Tap and With Perforated Bottom. Depth Erom Tap of Container - Inches Date 3011 1 2 3 1 5 6 Moisture Percent Ohms at 75°F. June 111 150 80 ‘ 10 25 50 50 22.7 15 170 125 50 25 30 10 21.1 16 190 150 75 60 60 50 18.1 17 210 175 100 80 90 90 16.2 18 225 175 120 100 100 100 11.1 19 22 5 175 120 110 130 100 12 . 7 21 225 190 110 130 110 130 11.1 23 225 210 160 150 160 150 9.2 21 225 220 170 170 175 160 8.1 25 230 225 175 175 175 170 7-5 26 250 250 180 175 _ 180 175 6.7 28 275 290 210 190 200 200 5.1 30 310 350 260 250 250 260 1.2 July 2 550 . 170 320 310 320 330 3.0 3 1.110 580 360 350 375 1475 2.3 5 6,300 1,050 180 175 580 1,650 1.7 9,200 1,200 510 500 650 2,250 1.6 6 30,000 2,700 775 700 1,250 9,000 1.1 8 300,000 21,000 2,900 2,300 11,700 300,000 0.8 9 910,000 11,000 7,200 1,750 30,500 780,000 0.7 W I .__1 ,fi 1 \ I x \ \ l . “ . r I r‘\ \. C —L 9 x I. \ 3 I ~\ f o a v C . c O . v - ,Q r _ ,1 I 7' 117 TABLE VIII. Laboratory Calibration -- Using Stratified Nylon Electrical Resistance Units in a Sand -- Container Open at Top and With Perforated Bottom. Date Depth From Top of Container - Inches Soil 1 2 3 1 5 6 Moisture Percent Ohms at 75°F. June 121, 150 80 ‘ 10 25 50 50 22.7 15 170 125 50 25 30 10 21.1 16 190 150 75 60 60 50 18.1 17 210 175 100 80 90 90 16.2 18 225 175 120 100 100 100 11.1 19 225 175 120 110 130 100 12.7 21 225 190 1110 130 1110 130 11.1 23 225 210 160 150 160 150 9.2 21 225 220 170 170 175 160 8.1 25 230 27.5 175 175 175 170 7.5 26 250 250 180 175 _ 180 175 6.7 28 275 290 210 190 200 200 5.1 30 310 350 260 250 250 260 1.2 July 2 550 . 170 320 310 320 330 3.0 3 1.110 580 360 350 375 175 2.3 5 6,300 1,050 180 175 580 1,650 1.7 9,200 1,200 510 500 650 2,250 1.6 6 30,000 2,700 775 700 1,250 9.000 1.1 8 300,000 21,000 2,900 2,300 11,700 300,000 0.8 9 910,000 11,000 7,200 1,750 30,500 780,000 0.7 N: 1:: H U-.I‘_——_ 1.- r71 .1. —1; Fw, r 1.411". , a y x r\ n C . _7 a 1 \ 1 _ _ v\. pk F. P\ 2 1 a _ 15 1 v\ .k '\ 2. 1 ’M r a 118 TABLE: IX. Laboratory Calibration - Using a Single Vertical Nylon Electrical Resistance Unit in a Soil Can With Perforated Bottom -- Grayling Sand, Gravelly Phase. Depth From Which 3011 Was Taken Dat e 6 Inch T8 Inch 36 13337— Ohms at Sofi‘“ Ohm at 5011— Ohms at 30:11 60°F. Moisture 60°F. Moisture , 60'F. Moisture Percent Percent Percent 31 170 23.8 280 20.9 210 17.1 September 1 320 22.0 520 18.9 600 15.7 2 500 20 .5 730 17 .1 900 11.2 3 660 18 .3 1,000 15 .2 1,200 12 .3 1 760 16.1 1,150 13.3 1, 350 10.1 s 810 11.3 1,200 11.0 1,150 8.5 6 960 12.1 1,100 8.7 1,650 6.5 8 1,100 8.6 2, 900 1.9 3,100 2.9 9 2,800 6.1 71,000 2.3 90,000 1.2 10 18,000 1.1 260,000 1.2 260,000 0.1 11 15,000 2.6 820,000 0.5 820,000 0.1 12 72,000 106 0000000 .000 0000'... one. 13 170’000 0.8 eoeeoee 000. 0.0000. eooe W -x [I h . 0 I. '9 ll r‘"\ J . .n,I \ :r‘ \ / “IN 7‘ \ , O... [1 ,‘I r ,\‘ ' r "f .-. .\, I? 2"“) Crown Diameter in Feet 17 7 16 1 15.1 11,4 13" 12-‘ 11" 10‘ IPPENDIIED H1 Figure 35. 555678910 D.B.H. in Inches Crown-diameter graph used to plot crown area. Figure 37. Subplot BO-B. C. ,2. 0" x a g" 5 ‘. Figure 39. Subplot 120-A. Figure 10. Subplot 120-8. 12S A \\1/,\\\;// \\|//,NV\uxn1/v,\\\/¢\»/r . floNfiW. «.an v0.» $1 nag .- ‘. \ ./ 9....Dx .nw ”name 0 Q / x 1.». 6.9... CP-«wfifi “,9 $1.» *8 90.6w! [effigy (\ Dy ‘9. VJU'V CC CerC/VG G Scale: 1.320! Figure 11. Subplot 120-0. Scale: 1'-20' Figure 12. Subplot 190-A. Enclosed areas show canopy ~ openings . 127' : E : Z : ' ‘fllgigI.gon ULit ,fi‘éiij": :flfifijfifii/é Scale: 1"-20' Figure 13. Subplot 190-B. Enclosed areas show canopy openings. 128 312:1: if Scale: 1'-20' Figure 11. Subplot 190-C. Enclosed areas show «:10ij openings. .‘. ('3, "I'- 9 'a \ I. I. D \1N’-“ " .I i; I“ W‘!“ ‘Q'L‘::' ; M31654 ' 06M USE ONLY. .’.. -~ ‘.I. oo.‘qs" “‘