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DEC ? 2 fa}! 086 GROWTH RESPONSE AND WATER USE EFFICIENCY OF PINUS BANKSIANA AND PINUS RESINOSA SEEDLINGS UNDER CONTROLLED MOISTURE REGIMES By William Graham Cole A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Forestry 1986 ABSTRACT GROWTH RESPONSE AND WATER USE EFFICIENCY OF PINUS BANKSIANA AND PINUS RESINOSA SEEDLINGS UNDER CONTROLLED MOISTURE REGIMES By William Graham Cole Pinus bangsiana Lamb. and Pinus resinosa Ait. seedlings were grown on undisturbed samples of four 7-3;. "v':_' _ In“... M texturally different soils under low stress and high stress moisture regimes. Low stress Pinus banksiana above-ground biomass growth was greater than for Pinus resinosa. High stress Pinus banksiana diameter and biomass growth were greater than for Pinus resinosa, but leaf area growth was less than for Pinus resinosa. Pinus banksiana high stress water use efficiency was greater than for Pinus resinosa. This difference was due to differential biomass growth rather than differential evapotranspiration among species. Optimum Pinus resinosa growth for all measured variables was on the dry-mesic sand. Pinus banksiaga growth was about equal on the dry-mesic and xeric sands, and much poorer on the wetter soils. ACKNOWLEDGMENTS I would like to thank the members of my committee, Dr. James Hanover, Dr. Donald Diokmann and Dr. Raymond Kunze, for so willingly sharing their time and wisdom with me. I owe a specieal debt of gratitude to my major professor, Dr. Kurt Pregitzer, for providing me with the opportunity to conduct this study. His insight, guidance and support were invaluable. Thanks go to Dr. Ronald Woessner and John Johnson of Mead Paper Corporation for their assistance in selecting sample sites and for providing the seedlings used in this study. I also want to thank Randy Klevickas, Roy Prentice and the staff at the Michigan State University Tree Research Center for all of their help. Thanks to all of my friends and colleagues in the MSU Forestry Department who helped make life a little easier and a lot more pleasant. Most importantly, I want to thank my wife, Abby. Her unending love and patience kept me going through it all. iii TABLE OF CONTENTS page LIST OF TABLES ........................................... vi LIST OF FIGURES ......................................... vii INTRODUCTION .............................................. 1 OBJECTIVES ................................................ 1 LITERATURE REVIEW ......................................... 2 METHODS AND MATERIALS ..................................... 6 Soil ................................................. 6 Soil Collection ................................. 6 Soil Analysis ................................... 7 Seedlings ............................................ 8 Seedling Establishment .......................... 8 Seedling Analysis ............................... 9 Moisture Treatments .................................. 9 Low Stress Treatment ............................ 9 High Stress Treatment .......................... 10 Experimental Design ................................. 12 Statistical Analysis ................................ 12 RESULTS .................................................. 13 Soil ................................................ 13 Seedlings ........................................... 21 Moisture Treatments ................................. 21 Low Stress Treatment ........................... 21 High Stress Treatment .......................... 26 DISCUSSION ............................................... 38 iv page CONCLUSIONS .............................................. 47 APPENDICES ............................................... 49 Appendix A: Soil Profile Descriptions ............... 49 Appendix B: Soil Sampling Tool ...................... 52 Appendix C: Data Points For Figures ................. 53 LITERATURE CITED ......................................... 54 LIST OF TABLES page Table 1. Moist bulk densities for upper 10 inches of 3 forest soils ................................... 14 Table 2. Moisture retention functions and coefficients ........................................ 16 Table 3. Average total water loss from three mineral soils during high stress period, July 1985 to October 1985 ........................................ 34 _ vi LIST OF FIGURES page Figure 1. Moisture retention curves for undisturbed samples of three mineral soils ...................... 15 Figure 2. Average Onaway Loam soil matric suction during high stress desorption cycles ................ 18 Figure 3. Average Kalkaska Sand soil matric suction during high stress desorption cycles ................ 19 Figure 4. Average Rubicon Sand soil matric suction during high stress desorption cycles ................ 20 Figure 5. Diameter growth during the low stress period, July 1984 to July 1985 .............................. 22 Figure 6. Height growth during the low stress period, July 1984 to July 1985 .............................. 24 Figure 7. Above-ground biomass growth during the low stress period, July 1984 to July 1985 ............... 25 Figure 8. Diameter growth during the high stress period, July 1985 to October 1985 ................... 27 Figure 9. Height growth during the high stress period, July 1985 to October 1985 ................... 28 Figure 10. Above-ground biomass growth during the high stress period, July 1985 to October 1985 ............ 29 Figure 11. Adjusted mean leaf area for the high stress period, July 1985 to October 1985 ............ 31 Figure 12. Water use efficiency for high stress period, July 1985 to October 1985 ................... 33 Figure 13. Average cumulative water loss from Onaway loam cores for six desorption cycles during the high stress period, July 1985 to October 1985 ....... 35 Figure 14. Average cumulative water loss from Kalkaska sand cores for six desorption cycles during the high stress period, July 1985 to October 1985 ....... 36 Figure 15. Average cumulative water loss from Rubicon sand cores for six desorption cycles during the high stress period, July 1985 to October 1985 ....... 37 K“ I:,. INTRODUCTION The Lake States forest products industry depends upon pine plantations for much of its supply of softwood (Nicholls 1979). Jack pine (Pinus bgnksigna Lamb.), once considered to be an undesirable commercial species, is now being harvested as pulpwood and sawtimber. If jack pine is to continue to be an important commercial resource, successful plantation establishment is essential (Hacker et al. 1983). Red pine (Pinus resingsa Ait.) has been planted extensively in Michigan, Wisconsin and Minnesota, and will continue to be an important softwood plantation species in this region (Nicholls 1979). However, plantation establishment can be difficult or impossible if proper site selection is overlooked (Hacker et a1. 1983, DeMent and Stone 1968, Rawinski et a1. 1980). OBJECTIVES The primary objective of this study was to assess the growth response of jack and red pine seedlings grown on four texturally different soils under controlled moisture regimes. The second objective was to develop an efficient and practicable system for conducting tree seedling moisture stress experiments in a controlled environment using undisturbed field soil samples. LITERATURE REVIEW Jack and red pine are frequent associates in natural Lake State forests (Alban 1978, Fowells 1965, Benzie 1977a, 1977b). Both jack and red pine are adapted to xeric conditions, but jack pine is generally considered to be better able to survive and compete on very xeric sandy soils (Schulte and Marshall 1983, Pereira and Kozlowski 1977). Both species, however, exhibit their best growth on well drained sandy loams (Benzie 1977a, 1977b, Hacker et al. 1983, Fowells 1965, Rawinski et al. 1980). Growth responses of red and jack pine to soil moisture regimes have been studied extensively. Schulte and Marshall (1983) reported that reduction in leaf area growth and stomatal conductance following induced soil moisture stress were more obvious in jack pine than in red pine. They concluded that the enhanced sensitivity and physiological response of jack pine to soil water deficits were a possible explanation for its ability to survive on very xeric sites where other species might perish. In another study, Pereira and Kozlowski (1977) reported that jack pine leaf water potential was higher (closer to zero on the negative potential scale) than for red pine under controlled moisture stress conditions, indicating jack pine’s ability to control water loss more effectively than red pine on droughty sites. Begg and Turner (1976) presented a discussion of water 3 use efficiency (WUE) as it relates to crop plant production. WUE is a measure of dry weight produced divided by evapotranspiration during the growth period. They proposed a simple and interpretable form of WUE as WUE = g plant dry weight produced, kg evapotranspiration but warned against the use of WUE as a direct measure of drought resistance. Plant productivity is often negatively correlated with drought resistance (Jarvis and Jarvis 1963, Reitz 1974). However, in the context of non-irrigated forest trees on xeric sites, selection of species or genotypes for establishment on dry sites should be based on drought resistance as well as productivity. Drought resistance at the seedling stage is especially important. The most critical period in the survival and growth of plantations on dry sites is in the first few years (Strothmann 1967, Miller and Schneider 1971, Hacker et al. 1983). Lambert, Boyle and Gardner (1972) pointed out the lack of research on quantitative soil moisture as it relates to pine seedling growth and field performance. Diameter growth in jack pine and red pine seedlings is controlled to a great extent by the immediate environmental and soil conditions (Lambert et al. 1972, Strothmann 1967, Tang and Kozlowski 1983). Radial growth is not directly influenced by the previous year’s growth conditions, except to the extent that detrimental conditions can lead to root injury 4 or other gross morphological and physiological injury that can inhibit seedling performance in subsequent years (Tang and Kozlowski 1983, Stone et al. 1954, Hacker et al. 1983). In contrast to diameter growth, current year jack and red pine height growth is directly affected by the environmental conditions present during terminal bud development in the previous year (Clements 1970), but is not totally independent of current conditions (Tang and Kozlowski 1983, Strothmann 1967, Lambert et al. 1972). Most normal height growth in jack and red pine in the Lake ;I States is completed by late June or early July, but stem . elongation may continue at a reduced rate through September (Rudolph 1964, Kramer and Kozlowski 1983, Kozlowski 1971, Kozlowski and Ward 1961, Strothmann 1967). Both species exhibit determinate shoot growth (Kramer and Kozlowski 1983, Kozlowski 1971, Clements 1970, Rudolph 1964). Terminal buds are formed in mid-summer, with subsequent cell differentiation occurring through early autumn (Rudolph 1964, Clements 1970, Kozlowski and Ward 1961). Jack pine may have two or more recurrent shoot flushes in one growing season (Rudolph 1964). Both species exhibit some degree of lammas and proleptic shoot growth as well (Kramer and Kozlowski 1983, Rudolph 1964, Kozlowski 1971). Though the techniques and instruments for measuring soil moisture status in the field exist, their use is not without limitations. Tensiometers may be used to measure the energy status of soil water under low suction (less 5 than 1.0 bar). While plants normally exhibit reduced transpiration and growth rates at sustained matric suctions greater than 1.0 bar (Hillel 1982), it may be of interest to quantify and study soils under higher soil moisture deficits. In situ thermocouple psychrometers are now available for measuring the free energy status of soil under high tensions, but these instruments are difficult to calibrate and use without the confounding errors of changing environmental conditions (Savage and Cass 1984). Non-destructive gravimetric moisture measurements are not practicable in field studies. However, use of potted soils lends itself well to gravimetric soil moisture measurements (Stransky and Wilson 1964, Wadleigh 1946). Recent studies relating seedling performance under simulated field conditions to actual field performance have been somewhat successful (Waxler and van Buijtenen 1981, Feret 1982). In the present study, red and jack pine seedlings were grown on undisturbed soil samples of four texturally different Michigan soils under two successive moisture regimes. Several seedling growth responses were measured in an attempt to detect differential species response to natural soil moisture characteristics. METHODS AND MATERIALS Soil Mm Soil cores were collected from four sites in May 1984. Three sites were recent clearcuts in Michigan’s Upper Peninsula and the fourth was a northern white cedar swamp in central Lower Michigan. The sites comprise the following soil series: Kalkaska sand, Rubicon sand, Onaway loam and Lupton muck. A 150 cm deep soil pit was described on each of the mineral soil sites. Soil pit descriptions and the site habitat types are presented in Appendix A. The pre-harvest forest on the Kalkaska site included red maple (Aggr rubrum L.), eastern hemlock (ngga cgnadensis (L.) Carr.), eastern white pine (Ping; strobus L.) and yellow birch (Betula alleghaniensis Britton). The Rubicon site was part of a large uniform outwash plain dominated by jack pine. Site preparation included row scalping to a depth of 5-10 cm, exposing the E horizon. Soil cores were extracted from within these trenches. Stand composition on the Onaway loam prior to clearcutting was primarily sugar maple (Aggr saccharum Marsh.), white birch (Betula pgpxrifigrg Marsh. and white ash (Fraxinus amerigana L.). The fourth site had a mixed overstory of northern white cedar (Ihgjg ocgidgntalis L.), black ash (Eraxinus Qigra Marsh.), trembling aspen (Populus 7 tremulgides Michx.), eastern larch (Larix larigina (Du Roi) K. Koch) and red maple. I Eighteen 6 x 6 x 10 inch deep square soil cores were taken at randomly located points within the sample area on each site, which was limited to less than 1/10 ha to maintain homogeneity among cores from a given site. The soil sampling tool is shown in Appendix B. The sleeve was driven into the ground vertically with the driver and cap assembly, and then carefully dug out with a shovel. The bottom of the core was trimmed flat before the sleeve and ii core were placed on the press stand. The extracted core was transferred into a polyethylene glycol coated paper plant band as the sleeve was pushed down over the press stand, and placed with three other cores in a plastic crate. Cores damaged during sampling or transfer to the paper cartons were discarded. Cores were transported to the Tree Research Center on the Michigan State University campus. 5 .1 A 1 . An average moist bulk density was calculated for each soil using 20 cm3 samples taken at three successive depths from eight cores of each mineral soil (Blake 1965). For each crate in which seedlings were planted a dry soil weight was calculated from the volume of soil in each core in that crate and the average bulk density. A mean weight of the plastic crates and four plant bands, plus an 8 estimated correction for four seedlings, was added to the soil weight to give an estimated total dry weight for each crate. Mass water content was measured at matric suctions of 15, 1.0, 0.33, 0.25, 0.1 and 0.05 bars for each of the mineral soils by equilibration in a pressure plate apparatus (Richards 1965). Undisturbed samples were extracted using PVC pipe rings (4.3 cm across x 2 cm deep) for use in the low matric suction determinations. The 15 bar determinations were performed on sieved samples (2 mm sieve) using 5 mm deep rings. The air entry matric suction at saturation was determined from measurements of the changes in color shading of drained vertical soil columns that were packed to each soil’s respective average bulk density (Hillel 1982). An inverse quadratic function was fit to the moisture retention data points from 0.05 to 1.0 bar matric suction, inclusive, using Plotit Statistical Software (Eisensmith 1985). The rentention curve between 1.0 and 15 bars matric suction was approximated by a linear funtion for each of the soils. Seedlings b ' nt One year old jack and red pine styro-block seedlings were donated by Mead Paper Corporation Woodlands Division 9 of Escanaba, Michigan. Trees were transplanted to soil cores during the last week of July 1984. Sixty-four seedlings of each species were chosen for transplantation on the basis of overall vigor and uniformity of height among each species. Initial mean heights of the seedlings were 14.68 i 1.21 cm for jack pine and 8.93 1 1.20 cm for red pine. W Root collar diameter and height (root collar to terminal bud tip) were measured on each transplanted seedling. Diameter, height and oven-dry weight of the above-ground portion of 20 red pine seedlings and 28 jack pine seedlings, selected on the same bases as those that were transplanted, were collected for subsequent derivation of a predictive biomass equation. Moisture Treatments Low St e The low stress treatment period began when the trees were transplanted to the soil cores and ran from July 1984 to July 1985. During this time, all crates with seedlings, plus several control crates of each of the three mineral soils which had no seedlings growing in them, were kept in an uncovered frame structure under ambient outdoor conditions and were uniformly watered from overhead 10 sprinklers as needed. Weeds that sprouted in the cores were pulled or clipped. The trees were protected over the winter by covering the structure with white polyethylene. The poly cover was removed and watering was resumed in the spring at bud break. Diameters and heights were measured in July 1985 at the end of the low stress treatment period. H t T t The frame structure was covered with clear polyethylene in July 1985. End and side walls of the house were left uncovered to control excessive heat and humidity. Overhead sprinklers were the only source of water for the seedlings during the high moisture stress period. Crates with trees and control crates were subjected to six desorption cycles from July 1985 to October 1985. Each desorption cycle was begun with a thorough overnight watering of all soil cores. The six concurrent cycles lasted 14, 12, 15, 14, 16 and 22 days, respectively. Crates were weighed to the nearest .01 kg approximately one hour after the water was shut off, and every few days thereafter. A 90 kg capacity GSE, Inc. model 4446 scale platform and model 620 digital display electronic indicator were used to weigh the crates. The mass water content on a per-crate basis was calculated using the measured wet weight and the calculated dry weight (Gardner 1965). When the average mass water content for jack and red pine on the two sandy soils fell below 9.0 %, 11 all seedlings and control cores were watered, thus beginning a new desorption cycle. The Lupton soil cores were kept saturated throughout both treatment periods. The matric suction of each crate was calculated from the regression equations and the moisture content for each weighing during the high stress period. A 1-inch diameter soil extractor was used to remove a column of soil from two cores of each crate during the final desorption cycle in October. The extracted column was divided into 5 equal segments which were placed in pre- weighed moisture cans for mass water content determination. The average of the 10 samples per crate was used to evaluate the accuracy of the indirectly measured mass water content. Final measurements of the treatment seedlings consisted of diameter, height and biomass. Stems (stems, branches and buds) and needles were oven dried separately at 700 C for 48 hours and weighed. The dry weights of treatment seedlings, and of seedlings harvested prior to the low stress treatment, were regressed against the 2 * H so that above-ground biomass could be variable D calcuated for each treatment seedling based on a known diameter and height prior to and after the low stress period. Cumulative needle length, L, was measured on 12 randomly selected treatment seedlings of each species. Linear regression functions were derived to predict L for the remaining seedlings from known dry weights. Mean 12 species needle width, w, was determined from 19 red pine and 24 jack pine needles randomly picked from several randomly chosen seedlings. Total foliar surface area was then computed for each seedling. A water use efficiency (WUE) ratio, defined as the quantity of above-ground dry matter produced divided by the quantity of water lost in evapotranspiration during a given period, was calculated for each species on each of the mineral soils. Change in weight of the crates was attributed to water lost in evapotranspiration. Experimental Design The study was a two-by-four factorially arranged completely randomized design with four replications per treatment combination and four subsamples per replication (2x4x4x4=128 seedlings). Two tree species and four soils were completely cross classified to produce eight unique species-soil treatment combinations (Steel and Torrie 1980). Statisitical Analysis Where appropriate, seedling measurements were tested for normality and homogeneity of variance with Number Cruncher Statistical System (NCSS 1986, Sokal and Rohlf 1981). Analyses of variance were performed on seedling 13 diameter, height and above-ground biomass increments for the low stress and high stress treatment periods. An analysis of covariance was performed on final total needle surface area, using July 1985 (pre-high-stress) stem diameter as a covariate term in the model. Analyses of variance and covariance were carried out with the GLM procedure of SAS on the Michigan State University IBM 4381 mainframe computer (SAS 1982). Significant main effect treatment factor means were compared for significant differences using Fisher’s protected LSD. In each of the analyses, error mean square and sample mean square were pooled. However, with conservative interpretation of the resultant probability levels, distinct ranges of significant and non-significant mean differences were apparent. Unless otherwise stated, the alpha level used to judge statistical significance was 0.05. RESULTS Soil Moist bulk densities of extracted mineral soil cores are shown in Table 1 along with published ranges for these soil series. Compaction due to sampling and transportation was not evident from these data. 14 Table 1. Moist bulk densities for upper 10 inches of three forest soils. Measured Bulk Reported Bulk Soil Series Density Density s/cm3 Onaway Loam 1.45 1.41-1.45 a b Kalkaska Sand 1.41 1.25-1 45 Rubicon Sand 1.44 1.36—1.60 b a. Padley et al. 1984 b. Frederick 1985 Moisture retention curves are shown in Figure 1. The functions, coefficients and r2 values for the curves are listed in Table 2, along with the linear equations for the 1.0-15.0 bar range. The graph illustrates the moisture gradient present among the soils. The Rubicon held less water per gram of soil than the Kalkaska at matric suctions greater than .10 bar. The Onaway loam had a gentler transition from low to high suction and a greater mass water content at a given suction than did the sands. The soil moisture gradient shown in the desorption data corresponded well to the edaphic gradient suggested by pre- harvest forest composition and to the soil survey descriptions of these soil series (Frederick 1985, Berndt 1977). Metric Suction (bars) 15 15.0— m D 1.00- i> t D Onaway : T A Kalkaska . o Rubkon 0.75- 0.50- 0.25-1 " C] 0'00 ""I"r'l""l""|""l"'—'|fi>'l“"l""l O 5 10 15 20 25 3O 35 4O 45 Moss Water Content (%) Figure 1. samples of three mineral soils. Moisture retention curves for undisturbed 16 Table 2. Moisture retention functions and coefficients.a 0.05-1.0 bar Y=X/(A*X2+B*X+C) Soil Series A B C 32 Onaway 1.1975 -20.7946 65.6737 .988 Kalkaska .5056 36.2386 -297.8605 .997 Rubicon 1.0309 6.9813 -58.9659 .994 1.0-15.0 bar Onaway Y = 31.668 - 2.132 * X Kalkaska Y = 27.805 - 3.158 * X Rubicon Y = 46.513 - 8.754 * X a. For both equations, X = (percent moisture, dry weight basis)*100, and Y = matric suction. 17 Direct gravimetric water content determinations of the mineral soil cores during the terminal desorption cycle resulted in the adjustment of previously estimated crate dry weights. The corrected dry weights ranged from 2.81 kg greater than to 2.72 kg less than the original estimates. The profiles of average treatment combination matric suction during the 86 day high stress period are shown in Figures 2, 3 and 4. The graphs show that the cores wetted to nearly the same matric suction at the beginning of each desorption cycle. However, a pattern of steeper ascent of soil matric suction for jack pine in nearly every desorption cycle on all three soils suggests that water loss occurred more quickly on these cores than on the red pine cores. The maximum average initial matric suction was 0.1 bar, which occurred on the Onaway-red pine treatment combination. Mean initial values were generally less than 0.05 bar for the sands and around 0.08 bar for the loam. Maximum average matric suction on the soils did not exceed 20 bars, although a few individual crate maxima exceeded 25 bars at the end of the second, third and fourth cycles. Metric Suction (bars) 18 10- Onowoy Loom a—a Jack Pine -+—+ Red Pine f 0 '1b 2'0'30 4'0r5'o so 70 80 90 Days Figure 2. Average Onaway loam soil matric suction .during high stress desorption cycles. Motflc Sucfion (bore) 19 Kalkaska Sand 15- H Jack Pine 14_ +—+- Red Pine 13— 3 3 121 11- iO~ 8~ 7.. 6.. 5- 4- 3_ 2_ 1- O ' I I ' T ' l“ l ""l ' l "T :l O 10 20 3O 4O 50 60 7O 80 90 Days Figure 3. Average Kalkaska sand soil matric suction during high stress desorption cycles. Metric Suction (bers) 14- i3- 12~ 11d 10-- 20 Rubicon Send B—El Jack Pine +—i- Red Pine I 'l J 1‘ .. l 0 10 '7 20 30 4050 60 7080 90 Deys Figure 4. Average Rubicon sand soil matric suction during high stress desorption cycles. 21 Seedlings Examination of seedlings revealed no evidence of lammas or proleptic shoot growth in any of the seedlings in this study. Tests for homogeneity of variance and normal distribution on seedling measurement data indicated no significant violation of the assumptions of analysis of variance and analysis of covariance. Moisture Treatments ow tr Treatm nt Mean seedling diameter growth after the one year low stress treatment period for jack pine was not significantly different from that of red pine across the range of soils (Figure 5). Diameter growth averaged 1.63 and 1.50 mm for jack pine and red pine, respectively. The soil main effect on mean diameter growth was significant, with the Kalkaska and Rubicon outperforming the Onaway and Lupton, but not significantly different from one another. The interaction main effect, represented graphically as the degree of non- parallelism between corresponding segments of the two species curves, was not significant. Jack pine diameter growth was greatest on the Rubicon (2.0 mm), though not significantly greater than on the Kalkaska (1.9 mm). Mean red pine diameter growth was significantly greater on the Kalkaska than on any of the other soils, averaging 1.9 mm. Diemeter Growth (mm) 22 25‘ Low Stress Diameter Growth ‘ LSD = .446 mm 2.0- 1.5a _ -F—+ Red PMe 1.0 B—a Jack Pine LUP'TON ONA'WAY KALKTASKA RUBiCON SoH Sefles Figure 5. Diameter growth during the low stress period, July 1984 to July 1985. 23 Mean height growth during the low stress period had a significant two-way interaction (alpha 2 .02), due primarily to the divergence of the means on the Rubicon series (Figure 6). Mean jack pine height growth was greater than that of red pine on all four soils. A strong soil main effect was present, with the combined species height growth during the low stress period showing a significant negative correlation to the moisture gradient. The combined seedling height growth means on the KalkaSka and Rubicon cores were the only two that were not significantly different from one another. Red pine height growth was greatest on the Kalkaska soil, averaging 4.95 cm. The greatest jack pine height growth, 10.58 cm, occurred on the Rubicon cores. The species main effect on net above-ground biomass growth during the low stress period was slightly significant. Jack pine seedlings averaged 1.7 g net growth and red pine averaged 1.4 g (Figure 7). Average seedling dry weight was not significantly different on the two sands, nor on the two wetter soils. However, significant differences were present between the former and the latter. Comparison of individual treatment combinations showed that red pine dry weight increase was clearly superior on the Kalkaska soil, and that jack pine grew equally well on the two sands. Neither species performed well on the wetter Lupton and Onaway cores. Height Growth (cm) 24 Low Stress Height Growth 12.01 1 1.04 10.0; 9.01 8.0— 7.0-3 6.04 5.03 4.0-3 3.0-1 2.05 1.0.: +——+ Red Pine ‘ B—a ‘ 0.0 Jack Pine LUP'TON ONAIWAY KALKIASKA RUBiCON LSD = 1.61 cm SON Senes Figure 6. Height growth during the low stress period, July 1984 to July 1985. Biomess Growth (9) 30: Low Stress Above—Ground : Biomass Growth 2.5—: 1 2.0: 1.5-: 1.0{ 0.5: LSD = .717 g : +—+ Red Pine 0.0- H Jack Pine LUP'TON ONA'WAY KALKTASKA RUBiCON SoH Sefles Figure 7. Above-ground biomass growth during the low stress period, July 1984 to July 1985. 26 High Stress Treatment No significant interaction was evident in the diameter growth response during the high stress treatment period (Figure 8). Mean jack pine diameter growth for the four soils was 0.96 mm, which was significantly greater than mean red pine growth, 0.57 mm. The soil main effect on diameter growth was not significant for the two species. Average jack pine diameter growth on the Kalkaska soil was 1.12 mm, which was significantly different only from the Lupton seedlings. Red pine high stress diameter growth was about equal on the Lupton and Onaway, 0.66 and 0.67 mm, respectively, slightly less on the Kalkaska, 0.54 mm, and poorest on the Rubicon, 0.40 mm. High stress treatment mean height growth is shown in Figure 9. Neither the species nor the interaction main effect was significant. Jack pine had an average height growth of 3.15 cm and red pine averaged 3.25 cm. Seedlings of both species had much better height growth on the organic muck than on the mineral soils during the high stress period. The Onaway seedling mean height growth was significantly greater than on the Rubicon soil. Biomass growth during the high stress treatment period was significantly different among species, but soil and interaction main effects were not significant. Jack pine seedling biomass increased an average 1.67 grams, while red pine seedlings averaged 1.22 grams net accumulation (Figure 10). Jack pine grew best on the Kalkaska , nearly as well Diemeter Growth (mm) 1.3- 1.1d 0.3 27 High Stress Diemeter Growth LSD =-- .357 mm ‘ +——+ Red Pine B—B Jack Pine Figure LUPITON ONAINAY KALKrASKA RUBiCON SoH Senes 8. Diameter growth during the high stress period, July 1985 to October 1985.‘ Height Growth (cm) 6.01 5.04 4.04 3.0- 1.0 28 High Stress Height Growth LSD = .750 cm ‘ +—i- Red Pine a—a Jack Pine LUPTTON ONATWAY KALKZASKA RUBiCON SoH Senes Figure 9. Height growth during the high stress period, July 1985 to October 1985. BiOmess Growth (9) 29 3.0: High Stress Above-Ground . Biomass Growth 2.5-} 2.0% l /\G 1.5: B— 1.0{ 0.51 LSD = .516 g : +—-+ Red Pine 0 0. 121—9 Jack Pine LUP'TON ONA'WAY KALKTASKA RUBiCON SoH Senes Figure 10. Above-ground biomass growth during the high stress period, July 1985 to October 1985. 30 on the Rubicon, and significantly less on the Onaway and Lupton soils. Red pine tree growth was about equal on the Onaway and Lupton cores, 1.29 and 1.28 grams respectively. The Kalkaska grown red pine showed slightly better biomass growth (1.41 grams) and the Rubicon trees showed significantly less dry weight increase than either the Onaway or Lupton seedlings. The linear regression equations derived to predict needle length from measured needle dry weight for the two species were: 381.73 x DW + 460.67 (r2 : .89) Jack pine L 459.55 x DW + 381.02 (r2 Red pine L .99). Needle surface area per seedling was then computed from the formula needle SA (cmz) : L x [ w + (pi) * w/2], which is the formula for the surface area of one half of a longitudinally bisected cylinder, excluding the end surfaces. Results of the analysis of covariance of needle surface area are presented in Figure 11. Adjusted mean leaf area values represent final treatment combination leaf area means minus a weighted correction factor to account for differences that existed prior to the high stress treatment period. Therefore, the means shown in Figure 11 indicate differences in final leaf area attributable to the high stress treatment period. sq crn / 1000) Ad]. Meen Leef Aree 31 High Stress 55‘ Adjusted Mean Leaf Area 5.5— .1 4.5— 3.5-4 +——+ Red Pine 25 B—Ei Jack Pine LUP'TON ONA'WAY KALK'ASKA Rusicow SON Senes Figure 11. Adjusted mean leaf area for the high stress period, July 1985 to October 1985. 32 The two-way soil-species interaction was not significant, although the red pine-Kalkaska treatment combination adjusted mean leaf area was significantly greater than that for the Onaway, Lupton or Rubicon. Adjusted mean jack pine needle surface area was not statistically different among the three mineral soils, but was much lower on the muck. The foliage of jack pine seedlings grown on the Lupton cores was shorter than the foliage of the mineral soil seedlings, and had developed a considerable degree of chlorosis by the end of the study. Both the species and soil main effects on foliar area were highly significant. Adjusted red pine leaf area was greater than that of jack pine on each of the four soils. Adjusted leaf surface area averaged over the two species was greatest on the Kalkaska series and was smallest on the Lupton soil, due in large part to the poor jack pine vigor on the Lupton cores. Red pine adjusted needle area on the Lupton and Onaway seedlings was not significantly different. Kalkaska grown seedling adjusted needle area was significantly greater than the Onaway or Rubicon. Results of the analysis of WUE are presented in Figure 12. Soil and interaction main effects were not significant at the 95 percent confidence level. The species main effect was significant. Jack and red pine WUE averaged .295 and .189, respectively, over the range of mineral soils. g Biomass/Kg water 0.5% 0.4- 0.2- 0.1A 0.0 33 High Stress Water Use Efficiency LSD =‘ .138 g/kg " 5 e////////fi ~1—+ Red Pine a—a Jack Pine ONA'WAY KALK'ASKA RUBiCON SON Senes Figure 12. Water use efficiency for the high stress period, July 1985 to October 1985. 34 Average total water loss from the soils during the six high stress treatment desorption cycles is shown in Table 3. Cumulative water loss through evapotranspiration from crates with seedlings and evaporative loss from control crates during the high stress treatment period are shown in Figures 13, 14 and 15. Although the graphs show that total water loss for each species varied slightly from cycle to cycle, cumulative total water loss for species on each soil was very similar. Table 3. Average total water loss from three mineral soils during high stress period, July 1985 to October 1985. .Jack Pine Red Pine Kg 1 s.d. Kg 1 s.d. Onaway 22.92 1.30 21.47 1.83 Kalkaska 23.34 1.59 25.13 1.52 Rubicon 24.44 1.21 25.99 1.44 35 Onaway Loam 6.01 13—51 Jack Pine +—+ Red Pine 5.0- _ a—a Control Kg Water LN .0 0 ' 1‘0 2'0 ' 3‘0 . 4‘0 ' 5'0 8'0 ' 7'0 ' 8'0 ' 9'0 Days Figure 13. Average cumulative water loss from Onaway loam cores for six desorption cycles during the high stress period, July 1985 to October 1985. 36 Kalkaska Sand 6.01 q B—El Jack Pine +—+ Red Pine 5.0- H Control Kg Water (N (P r . 0 I1'0 2'0 3'0 ' 4'0 ' 5'0 8'0 ' 70 I80 ' 9'0 Days Figure 14. Average cumulative water loss from Kalkaska sand cores for six desorption cycles during the high stress period, July 1985 to October 1985. Kg Water 37 Rubicon Sand 6.01 B—EJ Jack Pine +—+ Red PMe 5.0— - 3 12.—18 Control 4.04 3.01 0 ' 1'0 2'0 ' 3'0 ' 4'0 ' 5'0 —6'0 ' 7'0 ' 8'0 ' 9'0 Days Figure 15. Average cumulative water loss from Rubicon sand cores for six desorption cycles during the high stress period, July 1985 to October 1985. DISCUSSION The soil core extraction process used in this study was successful. Visual inspection of the cores after the seedlings were harvested, as well as the bulk density measurements, revealed little evidence of structural disturbance. The use of plastic crates as pots provided for relatively easy collection and transportation of the soil from the field sites to the TRC. The mass of the crates with four soil cores ranged from about 35 kg to 45 kg, depending upon the actual volume of soil and the quantity of water present in the soil in a given crate. Core extraction from soils with an appreciable clay fraction proved to be impossible because the fine textured soil stuck to the inside surfaces of the extractor sleeve. If the extracted core could be pressed out of the sleeve, which was not always the case, excessive compaction of the bottom few inches of the core had already occurred. The tool was subjected to considerable stress during the four weeks of soil collection. Various welds and a few of the case hardened steel components failed and required re-welding. The sharpened bottom edge of the sleeve received numerous nicks and dents from stones in the soil. With a bit of experience, however, it was possible to tell when the sleeve had come to rest on a large stone, in which case the tool was relocated and a new extraction attempted. The sharpened edge was able to cut through woody roots up to 38 39 1-2 cm in diameter. Roots larger than 2 cm either prevented the tool from further penetration, or transmitted vibrations through the soil core to the extent that soil structure was significantly affected. There were several possible sources of error in the estimation of crate dry weights. Core volume was determined from external dimensions of the cores. Cores could not be removed from their crates without being destroyed, so precise external measurement of each core was not possible. A mean bulk density was used for each soil series. The presence of stones or roots in the cores would result in either under- or over-estimation of dry weight. A plastic crate that weighed significantly more or less than the mean crate would also affect the net dry weight estimate. A more accurate method of determining crate dry weights would be to pre-weigh and label all crates and plant bands. The wet weight of the crate, plant bands and 4 freshly extracted cores would be recorded in the field. Soil samples from each hole would be placed in moisture cans for determination of field moisture content at the time of sampling. Errors could still arise from the presence of a large stone or root channel within a core, but the overall effect of these modifications should be to improve the accuracy of the moisture content determinations. A better understanding of the moisture content of field soil cores will yield more reliable 40 estimates of the physical state of water in the cores when destructive sampling is not desirable. Seedling diameter growth is a reflection of current growth conditions. In the absence of competition, both jack and red pine trees are generally most productive on well drained sandy loams, so the poor diameter growth on the Onaway during the low stress period was an indication of some limiting growth factor. This limiting growth factor was probably excessive water in the lower portion of the cores. The lattice design of the plastic crates created a soil-air interface at the bottom of the soil cores. Crates were kept on the ground within the protective structure, the floor of which was covered with polyethylene. The small air space below each crate was undoubtedly quite humid. The low evaporative potential of the air space and the low unsaturated conductivity of the soil led to a build up of water in the bottom of the cores. One would expect the effect to be more pronounced in the loam cores than in either of the sandy soils because the volumetric percentage of water in the pores was higher in the loam at a given matric suction. The low stress treatment period ran from July of 1984 through July of 1985. Height growth was measured only before and after the treatment period, so the precise timing of shoot growth during the low stress period is unknown. Weekly measurements of seedling diameter and 41 height would have allowed exact monitoring of shoot growth timing. No lammas shoot growth was observed in the fall of 1984, so presumably, most of the height growth attributed to the low stress period occurred in the spring flush of 1985. The watering regime was the same during bud development in 1984 and stem elongation in 1985, so whether shoot growth reflected primarily fall 1984 or spring 1985 growth conditions is of little concern. Comparison of relative performance of the species on the four soils is of greater interest. Jack pine height growth was directly and inversely related to increasing soil moisture across the range of soils. Red pine seedling height growth also improved with decreasing soil moisture, but unlike the jack pine seedlings, declined again on the Rubicon cores. Poorer growth of red pine on the Rubicon cores was not as pronounced in the height data as it was in the diameter results. The magnitude difference in species height growth can be attributed more to natural growth habit than to treatment effects. Jack pine is known to have faster early height growth than red pine (Alban 1978). The lack of significant diameter or biomass growth differences between species supports the hypothesis that total above-ground growth was not different for the two species. The pattern of seedling dry weight increment across the four soil types is virtually identical to that of diameter growth. The relation between leaf area and 42 conducting xylem area, known as the pipe model theory, has been presented a number of times in the literature (Waring et al. 1982, Grier and Waring 1974, Rogers and Hinkley 1979). Since most of a young seedling’s diameter is composed of xylem tissue, a high correlation between diameter and above-ground dry weight growth patterns is not unusual. For all three of the measured low stress variables, red pine performance was optimum on the Kalkaska cores, about equal on the Onaway and Rubicon soils, and poorest on the Lupton cores. Jack pine diameter and biomass growth was nearly equal on the two sands, and similar in magnitude to red pine on the Kalkaska. The apparently greater total growth of jack pine compared to red pine on the Rubicon cores is not due to better performance of the jack pine on this soil relative to the Kalkaska, but to impaired growth of the red pine. High stress treatment diameter growth clearly illustrated the difference in the ability of jack and red pine to resist moisture stress. Evidence that soil moisture stress was present was apparent in the reduced diameter growth of jack pine on the Rubicon relative to the Kalkaska, and in the improved growth on the loam relative to the other soils as compared to the low stress period. Jack pine can grow well on the finer textured loams if soil aeration is adequate and if resistance to root penetration is low (Hacker et al. 1983). 43 Red pine diameter growth was virtually equal on the loam and muck, and relatively lower on the sands. Poor red pine growth on imperfectly drained soils, such as the Lupton cores in the present study, is a well documented phenomenon (Benzie 1977b, Tang and Kozlowski 1983, Fowells 1965, Stone et al. 1954). The high stress treatment moisture regime of the Lupton soil was the same as that of the low stress period, so the poorer relative response of red pine on the three mineral soils was due to the altered moisture regime on these soils rather than to any change in the Lupton seedling behavior. Not only was the diameter growth of the mineral soil red pine seedlings relative to the Lupton seedlings greatly reduced, but the gradient seen in low stress growth, lowest on the Lupton to highest on the Kalkaska, was completely reversed following the high stress period. Results of the height growth analysis suggested that, even though the high stress treatment was applied after normal bud set in both species, height growth was still affected by the treatments. A nearly complete reversal of the low stress moisture gradient was seen. The height growth of jack pine on the Lupton cores was nearly equal to the low stress growth. Since the low stress treatment lasted longer and included the period of normal maximum height growth, jack pine seedlings on these cores were clearly under physiological "stress” due to some soil factor throughout the two treatment periods. This stress 44 was probably due to excessive water, but there was no direct evidence collected to support this hypothesis. Tang and Kozlowski (1983) showed that jack pine seedlings were more susceptible to damage and reduced growth than red pine under flooded conditions. Red pine height growth on the Lupton soils was greater during the high stress treatment period than during the low stress period. The reasons for this apparent anomaly were not clear from the data. Total high stress treatment height growth was smaller in magnitude than low stress height growth, but was not trivial. Due to the influence of a preformed bud in both red and jack pine, it is not intuitive that application of the high stress treatments during the period of greatest shoot growth in the spring would have elicited greater growth differences between the species or soils. During the period of maximum shoot growth in the late spring and early summer, stem elongation is less sensitive to current conditions than to bud development conditions in the previous fall. Therefore, height growth differences measured in the present study probably reflect differences between the species in the timing of shoot growth cessation under moisture stress. The results of the high stress treatment biomass analysis were similar to those of diameter and height. Relative seedling performance was not greatly affected on the Lupton and Onaway cores. Most of the change in relative behavior among the soils was due to the lower net 45 growth on the Kalkaska and Rubicon cores. The ability of jack pine to produce more net biomass during the high stress period is indicative of jack pine’s adaptation to drier sites. Leaf area growth was further evidence of the difference in species response to the moisture stress of this experiment. Red pine produced more needle surface area on the Kalkaska than on any other soil type, and more than jack pine on any soil. Greater production of leaf area in red pine seedlings was accompanied by relatively less diameter or height growth than jack pine, which suggests a carbon allocation pattern in red pine that is not as well suited to very dry conditions as that of jack pine. Greater leaf area and less sensitive stomatal control in response to water deficits (Pereira and Kozlowski 1977) would tend to create greater moisture deficits within the plant under soil moisture stress. During the same high stress treatment period, jack pine above-ground biomass growth pattern was directed more towards stem diameter growth, with less production of new leaf area. It is possible that the smaller needle surface area and the more linear growth habit of the jack pine seedlings led to greater soil insolation. More incident sunlight would raise the temperature of the surface soil and could lead to greater evaporation rates. Another explanation for the more rapid loss of water in the jack pine cores during 46 the high stress period is that jack pine water uptake was more rapid than for red pine. More rapid uptake of water by the seedlings during periods of moisture availability would be advantageous on excessively well drained sandy soils that have very low water holding capacity. The increase in water conducting tissue, indicated by the greater diameter growth in jack pine, supports the latter hypothesis. Differences in WUE may play an important role in the selection of species for a given site. A species’ ability to out compete other plants on a droughty site in the early years when root systems are shallow and photosynthetic area is small may depend on the most efficient use of the available water resources. The results of this study did not support the hypothesis that jack pine seedlings transpire less water than red pine seedlings under conditions of soil moisture stress. CONCLUSIONS The present study illustrated a number of important differences between jack and red pine seedlings in relation to soil moisture stress. 1. The low stress diameter, height and above-ground biomass results support the hypothesis that jack pine seedlings are better adapted to xeric Rubicon soils than red pine seedlings. 2. Low stress red pine seedling performance was best on the Kalkaska soils for all three measured variables. 3. Neither jack nor red pine is well adapted to poorly drained soils, regardless of soil texture. Diameter, height and biomass growth on the Lupton muck and Onaway loam was significantly less than on the better drained sands. 4. High moisture stress treatments induced even larger growth differences between the two pines. Jack pine diameter growth was significantly greater than for red pine over the three month high stress period. Height growth response was inconclusive due to the timing of the treatments. 5. Jack pine showed a trend of more rapid utilization of available water than red pine on the Kalkaska and Rubicon soils, which has significant implications on soils with 47 48 such low moisture holding capacities. The difference in water uptake patterns was not as pronounced on the Onaway cores . 6. Jack pine had a greater water use efficiency than red pine on all three mineral soils. This difference reflected jack pine’s greater net biomass growth rather than different amounts of total water use. APPEND I CES 50 Kalkaska Sand Location: SW 1/4 Secl4 T44N R20W, Alger County, Michigan Date: 5/22/84 Crew: Kurt S. Pregitzer, William G. Cole Of: 6 to 3 cm; partially decomposed hardwood litter. Oh: 3 to 0 cm; finely decomposed hardwood litter; pH 4.3; abrupt smooth boundary. E: 0 to 10 cm; brown (7.5YR 5/2) medium sand; weak fine crum structure; very friable; pH 4.5; abrupt wavy boundary. Bh: 10 to 15 cm; dark reddish brown (5YR 2.5/2) loamy sand; weak fine crum structure; very friable; pH 4.5; many fine roots; clear wavy boundary. Bhs: 15 to 29 cm; dark reddish brown (5YR 3/3) medium sand; weak very fine crum structure; very friable; pH 5.0; many fine roots; gradual wavy boundary. 85: 29 to 55 cm; strong brown (7.5YR 4/6) medium sand; single grained sturcture; loose; pH 5.6; clear wavy boundary. IIBsm: 55 to 80 cm: strong brown (7.5YR 4/6) coarse sand; massive parting to mod. med. SAB structure; very firm; pH 6.0; abrupt smooth boundary. IIIC: 80 to 110 cm; strong brown (7.5YR 5/6) medium sand; single grain structure; pH 6.5; loose. IVC: 110 to 150 am; fine sand; single grain structure. VC: 150+ cm; med. sand; single grain structure; loose. Landform: outwash plain Topographic Position: low flat ridgetop Aspect: - Slope: < 2 % Distance To Break In Landform: 65 ft, below Microrelief: pit and mound, rolling Site Description: Site was clearcut in past 5 to 10 years, re-planted to red pine 3 to 4 yrs ago. Pre-harvest stand composition included red maple, eastern hemlock, white pine, yellow birch, beech, white birch. Ground flora present included Maianthemum, Streptopus, Trientalis, Drxopteris. Probable Habitat Type was Tsuga-Maianthemum. 51 Rubicon Sand Location: NW 1/4 Se024 T45N R25W, Marquette County, Michigan Date: 5/18/84 Crew: Kurt S. Pregitzer, William G. Cole 01: 5.5 to 5.0 cm. Of: 5 to 2 cm. Oh: 2 to 0 cm; pH 4.0 A: 0 to 2 cm; very dark gray (10YR 3/1) medium sand; salt and pepper; weak fine crum structure; friable; pH 4.1; abrupt wavy boundary. E: 2 to 8 cm; brown (10YR 5/3) medium sand; single grain structure; loose; pH 4.5; abrupt smooth boundary. B51; 8 to 13 cm; strong brown (7.5YR 4/6) medium sand; weak fine SAB structure; friable; pH 5.6; clear smooth boundary. B32: 13 to 40 cm; strong brown (7.5YR 5/6) medium sand; weak fine crum structure; very friable; pH 6.5; clear smooth boundary. C: 40+ cm; yellowish brown (10YR 5/4) medium sand; single grain structure; loose; pH 7.0; very well sorted. Landform: part of a very large outwash plain Aspect: - Slope: 0 Microrelief: none Site Description: Site was clearcut, then row scalped to about 5 to 10 cm, exposing the E horizon. Seedlings will probably be planted in these furrows. Most of fine roots on site are in the top 10 cm of the mineral soil. Some charcoal in soil profile. Adjacent stand composition is open jack pine with understory of Gaglthgrig prgggmbgns, Vaccinium gngustifglium, Cladonia sp., Carex pensylvanniga, Arbutus menzeisii, Ptgridium aguilinum, and Arctostgphxlos uva-grsi. Habitat Type: Pinus-Vaccinium—Carex. Cap and Driver Assembly "—°id—’i 0 16 i——: Extractor Sleeve [—1 APPENDIX 8 Soil Sampling Tool 30-35 lbs it 11—41 3’1" Top View Side View 3 3/, 52 '5” |‘—5 ’16—’i Press Stand Figure 5 Jack pine L 1.32 O 1.22 K 1.96 R 2.02 Red pine L 1.09 O 1.45 K 1.92 R 1.57 Figgre 6 Jack pine L 4.31 O 7.36 K 9.37 R 10.58 Red pine L 1.61 O 3.35 K 4.95 R 4.18 Figurg 7 Jack APPENDIX C Data Points For Figures F u e 8 Jack pine L 0.75 O 0.98 K 1.12 R 0.96 Red pine L 0.66 n! O HHHHW a: m 511N052? wNOr‘C-i a HH - n c [U hNNH Hmmg 0.90 Figurg 11 Jack pine O 0.252 K 0.317 R 0.318 Red pine O 0.218 K 0.222 R 0.126 Figure 12 Jack pine L 2924.3 0 4574.8 K 4747.7 R 4081.2 Red pine L 4269.3 0 4694.6 K 6077.0 R 5144.3 53 LITERATURE CITED LITERATURE CITED Alban, D.H. 1978. Growth of adjacent red and jack pine plantations in the Lake States. J. For. 76:418-421. Begg, J.R. and N.C. Turner. 1976. Crop water deficits. Adv. Agron. 28:161-217. Benzie, J.W. 1977a. Manager’s handbook for jack pine in the North Central States. 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