CORRELATION BETWEEN SEVERAL ma CHARACTERISTICS or SUGAR MAPLE {Acm gAccH'ARUM MARSH.) AND THE MAPLE SAP AND SUGAR YIELDS mm for m. Dogma oi m b. MICHIGAN STATE UNIVERSITY Abdul Karim Tom: 1961 vvvv " " .‘ZJI'G IIIIIIIIIIIIZIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIlL 310409 6049 This is to certify that the thesis entitled Correlation Between Several Tree Characteristics of Sugar Maple (Acer Saccharum March.) and the Maple Sap and Sugar Yields presented by Abdul Karim Toma has been accepted towards fulfillment of the requirements for Ph. D. degree in Forestry Major professor Date May 3, 1961 0-169 LIBRARY Michigan State University ABSTRACT CORRELATION BETWEEN SEVERAL TREE CHARACTERISTICS OF SUGAR MAPLE (ACER SACCHARUM MARSH.) AND THE MAPLE SAP AND SUGAR YIELDS by Abdul Karim Toma Of the numerous studies made in the general field of maple sap products, only a few are concerned with the rela- tionship between the tree characteristics, on the one hand, and the sap and sugar yields, on the other. Furthermore, most of the publications concerned with this phase of maple sap products are based on inadequate sampling and, often, on unreliable statistical evidence. This study, therefore, was devoted to determine the relationships which exist between several tree character- istics and the sap and sugar yields. The characteristics studied were: d.b.h., basal area, tree height, tree volume, crown length, live crown ratio, crown diameter, and crown area. The experimental area is located in Baker Woodlot on the campus of Michigan State University. Tree measurements were made in the fall of 1952 for 52 trees and their yields of sap and sugar for the years 1953, 1954, and 1955 were recorded. 2 Abdul Karim Toma In order to obtain maximum information about the effect of the previously stated tree characteristics on the yields of sap and sugar, three distinct statistical procedures were conducted. These were: (1) analysis of variance, (2) simple correlation analysis, and (3) multiple correlation analysis. Calculations for these analyses were performed by MISTIC computer. This is a tape-input, digital, high-speed, elec- tronic computer. The results of this study were as follows: 1. Significant increases in the yields of sap and sugar are obtained from trees with larger diameters (d.b.h.). There are also indications that the increase in sugar production is not attributed only to the increase in the volume of sap pro- duced, but also to the higher sugar percentage in the sap of trees with larger diameters. 2. The effect of basal area, which was found significantly favorable, on the yields of sap and sugar is none other than that already expressed by d.b.h. 3. Consistent negative correlation existed between tree height and the yields of sap and sugar in the three study years, but this correlation was not significant. 4. Significant increases in the yields of sap and sugar are expected by the increased tree volume. 3 Abdul Karim Toma 5. No significant increases in sap and sugar yields are obtained by the increased crown length of a tree in this experimental area. 6. Live crown ratio was positively correlated with the yields of sap and sugar in all the study years, but this correlation was not significant except with sugar yield in 1955. 7. Significant increases in the yields of sap and sugar are obtained from trees with larger crown diameters. This experiment also shows that large crown diameter is equally effective in increasing sap and sugar yields. 8. Large crown area significantly increases the yields of sugar, but not that of sap. 9. The combined effect of d.b.h., height, crown diameter, and live crown ratio accounted for 19 percent of the sap and 32 percent of the sugar in this experimental woodlot. The correlation coefficient of the four tree characteristics with the sap was significant at the 1 percent level, and with the sugar at the .1 percent level of significance. 10. No significant improvement was achieved in predicting sap and sugar yields by a multiple correlation analysis involving four tree characteristics than by a simple corre- 1ation using d.b.h. data only. 4 Abdul Karim Toma 11. Since the four visual tree characteristics, namely, d.b.h., height, crown diameter, and live crown ratio, deter- mine only about one-fifth of the sap yield and about one- third of the sugar yield, the need for future research in genetic variability between trees and the effect of soil characteristics in determining sap and sugar production is stressed. CORRELATION BETWEEN SEVERAL TREE CHARACTERISTICS OF SUGAR MAPLE (ACER SACCHARUM MARSH.) AND THE MAPLE SAP AND SUGAR YIELDS BY Abdul Karim Toma A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Forestry 1961 ii ACKNOWLEDGEMENTS The author wishes to express his sincere appreciation to Professor P. W. Robbins who, as a chairman of the guidance committee, gave freely of his time and experience throughout the graduate program. Grateful acknowledgement is extended to Dr. T. D. Stevens, Head of the Forestry Department, for his constant advice and assistance given generously throughout the course of the study. Special acknowledgement is due to Dr. J. W. Wright and Dr. V. J. Rudolph for their critical review of the manuscript and for their many helpful suggestions. Appreciation is extended to Dr. D. P. White and Dr. L. A. Wolfanger, members of the author's guidance committee. The author is grateful to J. G. Williams and Dr. B. M. Cool for collecting field data upon which this study is based. Appreciation is also extended to Drs. R. K. Hudson, L. M. James, and to all the staff and faculty members of the Forestry Department whose kindness and genuine friendship made the author's study at Michigan State University a pleasant one. iii TABLE OF CONTENTS Page INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 1 LITERATURE REVIEW . . . . . . . . . . . . . . . . . . 12 LOCATION AND GENERAL DESCRIPTION OF THE EXPERIMENTAL AREA . . . . . . . . . . . . . . . . . . . . . . . 15 EXPERIMENTAL PROCEDURE AND COLLECTION OF DATA . . . . 18 STATISTICAL PROCEDURE . . . . . . . . . . . . . . . . 26 1. Analysis of Variance 26 2. Simple Correlation 26 3. Multiple Correlation 27 EFFECT OF D.B.H. ON THE MAPLE SAP AND SUGAR YIELDS . . 29 EFFECT OF BASAL AREA ON THE MAPLE SAP AND SUGAR YIELDS . . . . . . . . . . . . . . . . . . . . . . 37 EFFECT OF TREE HEIGHT ON THE MAPLE SAP AND SUGAR YIELDS . . . . . . . . . . . . . . . . . . . . . . 41 EFFECT OF TREE VOLUME ON THE YIELDS OF MAPLE SAP AND SUGAR 42 EFFECT OF CROWN LENGTH ON THE MAPLE SAP AND SUGAR YIELDS . . . . . . . . . . . . . . . . . . . . . . 43 EFFECT OF LIVE CROWN RATIO ON THE MAPLE SAP AND SUGAR YIELDS . . . . . . . . . . . . . . . . . . . 44 iv TABLE OF CONTENTS (Continued) Page EFFECT OF CROWN DIAMETER ON THE MAPLE SAP AND SUGAR YIELDS . . . . . . . . . . . . . . . . . . . . . . 45 EFFECT OF CROWN AREA ON THE YIELDS OF MAPLE SAP AND SUGAR . . . . . . . . . . . . . . . . . . . . . . 50 COMBINED EFFECT OF D.B.H., HEIGHT, CROWN DIAMETER, AND LIVE CROWN RATIO ON THE YIELDS OF MAPLE SAP AND SUGAR . . . . . . . . . . . . . . . . . . . . 51 A SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . 58 I LITERATURE CITED . . . . . . . . . . . . . . . . . . . 63 V APPENDIX . . . . . . . . . . . . . . . . . . . . . . . 68 LIST OF TABLES Table Page 1 Correlation coefficients . . . . . . . . . . . . 3O 2 Significant levels of the correlation coefficients . . . . . . . . . . . . . . . . . 31 3 F-values for the difference between the means of d.b.h. classes . . . . . . . . . . . . . . . 34 4 Values for the least significant differences between the means of d.b.h. classes. . . . . . . 35 5 F-values for the difference between the means of crown diameter clases . . . . . . . . . . . . 47 6 Values for the least significant difference between the means of crown diameter classes . . 48 7 Summary table for the multiple correlation analysis . . . . . . . . . . . . . . . . . . . . 52 Figure LIST OF FIGURES Map of the Experimental Area . . . . . . . Photograph Showing a Bucket Hung on a Tree Photograph Showing Sap weighing and Sugar Contents Measuring Procedures . . . . . . Photograph of a Refractometer . . . . . . Histogram Showing the Average Sap Produced per Tree by Years . . . . . . . . . . . Histogram Showing the Average Sap and Sugar Produced per Tree by D.B.H. Classes . . . Histogram Showing the Average Sap and Sugar Produced per Tree by Crown Diameter Classes vi Page 17 22 23 24 25 33 49 49 vii LIST OF ANALYSES IN THE APPENDIX Analysis Page 1 D.b.h. classes and sap yields of 1953 . . . . 68 2 D.b.h. classes and sap yields of 1954 . . . . 69 3 D.b.h. classes and sap yields of 1955 . . . . 7O 4 D.B.H. classes and sap yields of 1953 through 1955. . . . . . . . . . . . . . . . . 71 5 D.b.h. classes and sugar yields of 1953 . . . 72 6 D.b.h. classes and sugar yields of 1954 . . . 73 7 D.b.h. classes and sugar yields of 1955 . . . 74 8 D.b.h. classes and sugar yields of 1953 through 1955 . . . . . . . . . . . . . . . . 75 9 Crown diameter classes and sap yield of 1953 . . . . . . . . . . . . . . . . . . . . 76 10 Crown diameter classes and sap yield of 1954 . . . . . . . . . . . . . . . . . . . . 77 11 Crown diameter classes and sap yield of 1955 . . . . . . . . . . . . . . . . . . . . 78 12 Crown diameter classes and sap yield of 1953 through 1955 3 . . . . . . . . . . . . . 79 13 Crown diameter classes and sugar yield of 1953 O O O O O O O O O O O O O O O O I O O O 80 Analysis 14 15 16 LIST OF ANALYSES (Continued) Crown diameter classes and sugar yield of 1954 . . . . . . . Crown diameter classes and sugar yield of 1955 . . . . . . Crown diameter classes and sugar yield of 1953 through 1955 . viii Page 81 82 83 INTRODUCTION The maple syrup and sugar industry is confined to North America. Although some believe that early French settlers taught the American Indians the techniques of making maple syrup and sugar, the majority of writers (g, _4, gZJ ggy _§)l believe that it was the Indians who taught the European pioneers. The writings of early American settlers dating as far back as the year 1521 (31) show that this industry was a well established practice among the Indianltribes. Income from maple sap products constitutes a small portion of the national economy. The annual national gn- come from maple sap products for the period between 1943 and 1954 averaged a little over 7,250,000 dollars (4;). With its average annual production valued at approximately 400,000 dollars during that period, Michigan ranks fourth or fifth among the maple sap producing states. This con- tributes substantially to the income of many woodland and sugar grove owners. lThe underlined-numbers in parentheses refer to the literature cited. Production of maple syrup and sugar in commercial quantities is confined to the eastern and northern United States and the neighboring southeastern part of Canada (3, 21” _§). There are only eleven states in the United States which produce syrup and sugar in commercial quantities. These states are, in descending order of the average number of trees tapped per year (1949-1958), Vermont, New York, Ohio, Michigan, Pennsylvania, Wisconsin,.Maine,.Minnesota, and Maryland (QED. Of the 13 species of maple native to the United States, only sugar maple (Acer saccharum Marsh.)2 and black maple (Acer nigrum Michx. f.) are of importance in the production of syrup and sugar in commercial quantities (lJ ggJ _§). These two species have approximately equal capacity for sap production. Because of its wider range of distribution and more frequent occurrence, sugar maple, however, contributes most of the sap produced. For some time, plant physiologists have been aware that in several genera, including Acer, Betula, Juglans, Ostrya, and Vitis, transitory pressure is developed in the vessel sap of their stems (25). Upon wounding of the stem, exudation is formed which in Acer gpp, is sap containing 2Scientific names are according to Little (22). varied amounts of sugar that may be converted into syrup or sugar by concentrating at boiling temperature. Sugar in the maple sap comes from carbohydrates accumulated in the tree as starch during the previous summer. When the weather becomes cool, the starch is con- verted into sugar. This results in a relatively high con- centration of sugar in the xylem sap. Sugar solution drains out of holes bored in the stem if conditions are favorable for the existence of pressure in the xylem (29). The exact cause of maple sap flow is not yet deter- mined in spite of numerous physiological studies. Marvin (25), conducted intensive study in an effort to determine the mechanism or mechanisms responsible for the flow of sap. He concluded: An explanation of the mechanism producing sap pressures and flows in maple stems based on a single physical phenomenon such as thermal expansion seems inadequate. A more acceptable point of view is that the sap flow results from the interaction of two or more factors . . . . During the cooling part of the temperature cycle there is an absorption of water or the vessel solution from the vessel by other xylem cells. This absorption is independent of the compo- 'sition of the vessel solution and may be in part a physical phenomenon. It apparently does not depend entirely upon the activities of living cells. The vessel solution is then replaced by absorption from -the roots. we.have called this absorption on cooling the conditioning period. It appears to be quantita- tively related to the volume of flow following warming . . . . After adequate conditioning, sap 4 pressures and flow may occur on warming. There is evidence that living cells are necessary and the composition of the vessel solution is important. The mechanism may be osmotic and the pressures and flow depend on D.P.D. across the ray cells between the ultimate reservoirs and the vessel solution. Whatever physiological activities may take place within the stem cells and vessels, however, it is now certain that the alternating freezing and thawing of the stem control sap flow (1.8.. 2_3_. is. as, 21. .3...)- The effect of weather, prior to and during the flow, on sap and sugar production, is one of the most thoroughly discussed topics in maple sap products literature. This is expected because the flow of sap itself is dependent on the temperature. To substantiate this, severed stems of maple trees exuded sap upon proper control of temperature (18, 23, _§). Maple trees, therefore, will produce sap during the dormant season, each time a period of freezing is followed by a period of thawing (45). A rise in temperature following a period of low, but not necessarily freezing temperature, is essential for the flow of sap. Hewever, the volume of flow is greater when the preceding temperature drops below 320 F. than when the lowest temperature between the flows is above 320 F. (24). It has been found that the more often the temperature fluc- tuates between freezing and thawing the better the sap flow season (22). The best runs have been reported to occur after sudden and rapid thaws with temperatures above 400 F. fol- lowing freezing nights (2, 2_). Reports on the effect of weather conditions during the growing season preceding the sap flow are somewhat contra- dictory. On the one hand, it is reported (28) that drought during the summer greatly reduced the subsequent sap yield. On the other hand, later investigators (2, 21) failed to report any significant correlation between the sap yield and weather conditions previous to the sap flow. Because of the statistical evidence presented by the latter group, the writer is of the Opinion that no significant correlation exists between the volume of sap and weather conditions prior to sap flow. The flow of sap is not a continuous process; that is, sap does not flow constantly all the time from the beginning of the season till the end. It only flows when atmospheric conditions are favorable during the season. Generally, there are 6 to 10 runs within each sap season. These are separated by non-flow periods ranging from one to several days. The starting dates of sap flow vary from year to year and from one place to another, depending upon weather conditions and geographic locations. For instance, sap season in Maryland or Ohio starts a week or two earlier than in the more northerly states such as Maine or Minnesota. With the same latitude, the season starts earlier in lower elevations than in higher elevations. In any one area, sap season starts earlier in some years than in other years if the rise in temperature following the freezing period of the winter is unseasonably early. If, on the other hand, the day and night temperature stay at freezing mark or below until the spring, sap season is, consequently, delayed. The sap season therefore, may start at any time between late January and the middle of March. As the beginning of sap season is influenced by temperature, so is its termination. So long as the temperature during the day is preceded by freezing or near freezing temperatures at night, sap will continue to flow. If, however, the day and night tempera- tures continue to be above freezing, sap stops flowing and the season comes to an end. Sap season in northern states and in higher elevations lasts longer than in the more southerly states and in lower elevations by 10 to 15 days. In the region as a whole, sap season usually ends between the middle of March and the middle of April. Radio fore- casts of the correct tapping dates are provided for sugar grove owners in several states including Massachusetts, Michigan, New York, Vermont, and Wisconsin (22, 22, 45). The sap and sugar yields vary from year to year, from sugar bush to sugar bush, from tree to tree, and from day to day during the sap season (2, 2, _Q, 22, 22, 22, 2_). These variations are due to: (1) the difference in climatic condi- tions during the sap season from one year to another, (2) the difference in soil characteristics between different sugar bushes, (3) the inherent tree characteristics for sap pro- duction (genetic variation between trees), (4) the difference in the physical tree characteristics such as stem diameter, height, crown diameter and length, etc., and (5) unknown factors. The average sap produced per tree ranges from 10 to 40 gallons annually, but yields as high as 130 gallons have been reported.3 Sugar concentration in the sap varies from .5 to as high as 7 and even 10 percent, but ordinarily it is between 2 and 3 percent (2, _Q). With an individual tree, sugar concentration in the sap is low early in the season, rises quickly to a maximum, then gradually decreases as the season advances (49). Maple sap is free from bacteria, yeasts or molds when in the tree (22). It becomes contaminated in the taphole, spout or in the bucket. As the season advances, infection becomes more severe and produces the so-called "buddy sap" 3Unpublished data, Forestry Department, Michigan State University. or sour sap. The growth of microorganisms in the maple tree taphole results in a decreased rate and often complete stoppage of sap flow (29, 2_). Yields from trees tapped early in the season are much more likely to be affected by microbial growth, even in a relatively cold season, than trees tapped at later dates (23). In an effort to determine the exact causes of pre- mature stoppage of sugar maple sap production, intensive study was conducted by Ching and Mericle (4). They concluded: Histological findings indicate that premature stoppage of sap flow in normally tapped maple trees results from the combined effects of a bacterial invasion of the living tissue via pits along the cell walls, and an actual vessel blockage by microorganisms and/or gummy plugs produced by these microorganisms. Demonstration of pectolytic activity in the bacteria isolated from tapholes suggests a mechanism whereby these organisms penetrate the pit membranes. The most promising method of combatting microorganisms which result in premature stoppage of sap flow has been found recently by Sheneman and his coworkers (23). It consists of inserting a pellet containing paraformaldehyde with agar into the taphole during the tapping operation. The effect of grazing on the yields of sap and sugar is a matter of dispute among the writers. One group (29, 22) reported substantial decrease in the yields of sap and sugar as a result of grazing. However, no statistical evidence was presented. The other group (_Q, _l), with reliable statis- tical evidence, found that yields from grazed groves were as high or higher than from ungrazed areas, but the difference was not statistically significant. Consequently, the writer is convinced that grazing has no significant effect on the yields of sap and sugar. However, the harmful effect of grazing on the physical properties of soil and on the young reproduction is well realized (2, 2, _Q, 22, 2g, 22, _2). In reviewing the literature, the writer noted several comments as to the effect that different types of soil may have upon sap yield and sugar percentage. They were mainly speculations with no statistical evidence of the superiority of one soil type over others in relation to maple sap and sugar yields. Moore and others (21) failed to establish any signi- ficant difference between sap yields of several soil types, except as was related to drainage, depth of topsoil, and tilth. White and Rdbbins (42), using different combinations of nitrogen, phosphorus, and potassium, commercial fertilizer, found that trees receiving nitrogen and phosphorus gave significantly higher sap yields than the trees receiving other treatments. In the same experiment, they found that there are indications that potash depresses the yields. 10 Trees of similar growth rate, crown and diameter sizes, growing on the same soil, vary considerably in their capacity to produce sap and sugar. This, then, suggests that factors other than environmental, perhaps genetic, may be partly responsible for this variation. Genetic efforts to improve sap producing qualities of maple trees have been very scant. In fact, the few attempts made in this direction were to propagate trees of high sugar concentration by means of cuttings (22, 22, 2_). The initial rooting was very poor. Later, with improved techniques and better care, rooting was increased to about 35 percent. Best results were obtained with cuttings taken from current season's growth. They were planted in indoor shaded beds and sprinkled frequently with water. Adaptation of the rooted cuttings to the field or to nursery conditions in tne open, however, was not encouraging. Despite the numerous studies made in the general field of maple sap products, only a few are concefned with the relationship between tree characteristics such as d.b.h., height, crown width and length and the sap and sugar yields. In addition, most of the publications devoted to this phase of maple sap products are based on inadequate sampling and, often, on unreliable statistical procedures. 11 This study is an attempt to determine the relationships which exist between several tree characteristics and the sap and sugar yields. The characteristics studied are: D.B.H. (diameter at breast height, approximately four and one-half feet from the ground) in inches. (D.B.H.)2 as an expression of the basal area in square inches. Total tree height in feet. (D.B.H.)2 x height as an expression of volume in cubic feet. Crown length in feet. Live crown ratio in percent. Crown diameter in feet. (Crown diameter)2 as an expression of crown area in square feet. 12 LITERATURE REVIEW Several workers (2, g, __E_'>_, ___6_, _6, £2, 22, 3_2_, 4_5) anti- cipate an increase in the yield of sap by tapping additional holes in a tree. As a general rule, they recommend one tap— hole for a 10 to lS-inch (d.b.h.) tree, two tapholes for a 16- to 20—inch tree, three tapholes for a 21— to 25-inch tree, and four tapholes for trees over 25 inches in diameter. Other investigators (Z, _l), on the other hand, failed to report any significant difference in the yields of sap due to the addition of more tapholes on trees of comparable diameter classes. Due to inadequate sampling reported by the latter group, the writer holds the conviction that the ‘addition of more buckets to a tree, especially to those with larger diameter classes, will result in significantly higher sap yields. Moore _§_§2, (21), in a test based on four—year average of 35 plots, reported an increase in both the volume of sap and sugar percent due to increase of d.b.h. In another experiment, Lawrence (22) feund significant increase in sap yield and sugar percent for those trees with bigger d.b.h. in comparison with those with smaller d.b.h. Morrow (29), reports that significant correlation exists between live crown ratio and sugar percentage for trees in 13 open stands. Others (2, 21) report that marked increases in the volume of sap and its sugar content are obtained from trees with larger live crown ratio. That a large photosynthetic surface (leaf area) is a prerequisite for increased sugar production in maple trees is well recognized (2, 22, 2Q, 22, 21, 2_). Significant increases in sap yield and sugar percent were reported for trees with larger crown diameter compared with those of smaller diameter (22, 21, 2_). McIntyre (26), in an experi- ment including large numbers of trees, showed evidence of increased sap flow with the increase of crown size. Morrow (22) found that crown diameter was correlated with increased sap flow much more than with sugar percentage. He also found that the influence of crown diameter on sugar percentage was greater in a closed forest than that of the live crown ratio, although the latter had greater effect on sugar percent in Open type sugar bush than the former. White (24) found that sugar percent in the sap yield of trees growing in open stands or along roadsides was significantly higher than that of forest grown trees. Roadside trees were reported (38) to yield sap with higher sugar percent than trees growing in open stands. In addition to their higher sugar contents, Willit (42) observes that open grown trees are excellent sap 14 producers. This is explained (22) by more rapid fluctuation between freezing and thawing in the open than in the forest, which directly hastens or retards sap flow. 15 LOCATION AND GENERAL DESCRIPTION OF THE EXPERIMENTAL AREA The experimental area with which this study is con- cerned is about 6 acres in size and is located on the north- east corner of the 77-acre Baker WOodlot on the campus of Michigan State University, East Lansing, Michigan. This woodlot is a part of the initial land grant to this university which was established in 1855, then known as Michigan Agricul- tural College. It is located in Section 19, Township 4N, Range 1W, Ingham County, Michigan. The experimental portion of the woodlot is a mixed hardwood stand containing a high proportion of sugar maple. Other species present are red oak (22ercus rubra, L.), bass- wood (Tilia americana, L.), black cherry (Prunus serotina, Ehrh.), and American elm (Ulmus americana, L.). The woodlot is well protected from fire and grazing. Some intermediate cuttings have been made since 1914, with major harvest cuts in 1938 and in 1947, and, in small portions of the woodlot, experimental wildlife cuttings were made in 1933 and 1950. The site of the experimental area is well drained, with Miami and Hillsdale sandy loam soils on level to gently undulating terrain. Maple trees vary in size to over 30 inChes in diameter, with ample reproduction in the understory. 16 The trees in this woodlot were tapped for this experiment for the first time, hence, the hazard from previous injuries due to tapping is eliminated. 1'? BAKE R WOODLOT Ix scALz I“-Iu‘ IEEOH- SUGAR LEGEND —. IUIOVED ROAD 2... W000! ROAD /' TYPE LINE BEECH-800A MAPLE \\ \I H ate-autos: I: I M , .. i O f FIGURE 1 '18 EXPERIMENTAL PROCEDURE AND COLLECTION OF DATA In the fall of 1952, the tappable maple trees, 10 inches and over, were selected and numbered with white paint on the west side of the trunk. The d.b.h. to the nearest tenth of an inch, total height in feet, and their crown length and diameter in feet were recorded. In the winter of 1953, a study on maple sap and sugar production for 120 selected trees was initiated in Baker WOOlet. Some trees were assigned one bucket, others two, and some others three buckets. The study was aimed at determining the effect that some production techniques such as height, depth and diameter of the taphole, number of tapholes per tree, type of spout and container, several tree characteristics, as well as weather factors, may have on maple sap and sugar yields. This study is concerned only with the 52 trees that were assigned one bucket to determine the effect of d.b.h., basal area, height, volume, crown length, live crown ratio, crown diameter, and crown area on I the yields of sap and sugar. . 19 Each year during the sap seasons of 1953 through 1955, the trees were tapped at randomly selected compass positions at a height 2 to 3 feet from the ground. The holes were drilled with a brace and an ordinary tapping bit. Two different types of spouts with three-eighths and seven- sixteenths of an inch in diameter were used to lead the sap from the tree to the collecting container. The container was either a metal bucket with snap-on cover or a plastic bag with a flap on top to prevent rain and other materials from falling into the sap. It has been reported by Cool (1) covering other phases of this study that no significant difference was detected between yields of sap and sugar due to: (1) height of taphole from the ground; (2) depth of taphole, ranging from 2 to 6 inches; (3) diameter of taphole, ranging from three-eighths to fifteen—sixteenths of an inch; (4) type of spout design; and (5) type of receiving container. At the beginning of each sap season, the trees were tapped 24 to 48 hours ahead of the first sap flow predicted by the Office of the United States weather Bureau at East Lansing and the Michigan State University Forestry Depart- ment cooperating. Tapping just shortly before the sap starts flowing is very important, since, as it has been 20 pointed out earlier, too early a tapping may reduce the yield substantially due to the infection by bacteria and other microorganisms even in a relatively cold season. For the 1953 sap season, the first sap collection was made on February 20 and the last on April 8, with eight major runs separated by non-flow periods ranging from one to several days. The total sap produced by the 52 trees was 6,522 pounds for an average of 125.4 pounds (or 15 gallons) per tree. The first run of sap during the 1954 season was collected on February 15 and the last on April 7, with 9 major runs. It gave a total sap yield of 10,916 pounds and an average of 210.0 pounds (or 25 gallons) per tree. In 1955, the sap started flowing on February 20 and it stopped on April 5, with 8 major runs in between. Total sap yield was 10,530 pounds for an average of 202.5 pounds (or 24 gallons) per tree. During each day, when a major run occurred, the sap was collected in the afternoon. The contents of the bucket or the bag were poured into a pail on which a standard dairy milk scale was attached, and the weight was recorded to the nearest tenth of a pound. The percent sugar was determined by placing a few drops of fresh sap in the Bausch and Lomb Hand Refractometer. The refractometer actually measures the 21 density of the sap expressed in percent of total solids (Brix scale). These solids contain, along with sugar, minute quantities of proteins and minerals, but the scale corresponds very closely with total sugar in the sap (2, 1, 2 ). Tree measurements as well as the collection of sap and sugar data for the 1953 and 1954 seasons were made by J. G. Williams, a graduate assistant at Michigan State Univer- sity (Forestry Department). The sap and sugar data for the 1955 season were collected by B. M. Cool, also a graduate assistant in the same department. The entire field work for this project was under the guidance of P. W. Robbins, Associate Professor of Forestry, Michigan State University. Sugar yield was calculated by multiplying the daily sap reading for each tree by its corresponding sugar percent and the yield of sugar for that tree and day was recorded to the nearest one-hundredth of a pound. At the end of each season, the sugar yields for all the 52 trees were added to determine total sugar production for that season. The total sap yields for the three seasons are presented graphically in figure 5. 3‘. r C N 5.53% EZH uuuuu ooo. Hoa.u Hma. uuuuu ooo.a uuuuu woo. armamm mmv. IIIIIIIIIIIIIII mHm . IIIII OOO.H IIIII mmHm Hmmmm lllll mam. an. HoH. IIIII moo. IIIII ooo.H .C.Q.Q umom quUHom Comm mumsvm Boom CH poem Doom mumsvm OH\ CH CH oHumH CH UHQCU poem CH monoCH moum HouoEmHo Czoao CumCoH CH CH moan CH moHumHHouomumso .CBOHU C30HU o>HH CBOHO oECHo> qume Hmmmm .C.Q.Q woke moHon Hmmsm oCm mam onmE oCm moHpmHHouomnmno oomu Coosuon mpCoHonmooo COHpmHoHuou .H mqm<9 31 mo. mo. IIIIIIIIII mo. IIIII H00. H00. mmlmmmH Hmmsm mo. Ho. mo. nnnnn Hoo. lllll H00. H00. mmma ummum IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII wmmH HmmCm mo. mo. IIIIIIIIII Ho. IIIII H00. H00. mmmH Hmmsm uuuuuuuuuuuuuuuuuuuu mo. unnuu Ho. Ho. mmnmmmH mmm IIIII mo. IIIII IIIII Hoo. IIIII H00. H00. mmmH mom uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu vmma Cmm uuuuuuuuuuuuuuuuuuuu Ho. In--- H00. H00. mmma Cam Hoo. IIIIIIIIIIIIIII Hoo. IIIII Hoo. IIIII mwnm CBOHU lllll HOG. lllll lllll lllll lllll lllll HOO. HQHOEMHG §OHU IIIIIIIIII H00. H00. IIIII IIIII IIIII IIIII uCoouom CBOHU o>HH uuuuuuuuuu H00. H00. .11.: Ace. null- nuns: Cumcma C3ouo Hoo. IIIIIIIIIIIIIII Hoo. IIIII Hoo. IIIII oECHo> IIIIIIIIIIIIIII Hoo. null: Hoo. null: null: quHmm H00. IIIIIIIIIIIIIII HOO. IIIII HOO. IIIII mmHm Hmmmm lllll Hoo. null: IIIII null: null: IIIII Hoo. .C.Q.Q Comm uCoUHoQ uwom ohmswm poem CH umom Comm ohmsvm OH\ CH CH oHumH CH UHQCU umom CH wonoCH mono HouoEmHo CBOHU CumCoH CH CH moum CH moHumHuouomCmno CBOHU CBOHU o>Hq C3ono wECHo> CCmHom Hmmmm .£.Q.Q moms Hmmsm oCm mom mo moHoH> onu oCm moHCmHCoHomumCU oouu Coosuon mCoHHMHoHHoo Mom mHo>oH ooCmonHCmHm .N mamas 32 of different d.b.h. classes. Four d.b.h. classes were distin- guished, each consisting of 11 randomly selected trees. Their yields of sap and sugar were analyzed separately for each season, and a separate analysis was devoted to the combined yield of the three—year period. Figure 6 presents the yields of sap and sugar for the three-year period by diameter classes. The levels of significance between yields of sap and sugar for the three seasons and their combined totals are presented in Table 3. Table 4 presents the average yields of sap and sugar for each diameter class and year, as well as the least signi— ficant difference at 5 percent and 1 percent levels. Among other significant relationships, the data in Table 4 show that the three-year total sap for the 14.6 to 19.8 inch diameter class is significantly higher than that for the smaller diameter classes. In regards to three—year total sugar production, the yield by the largest diameter class is significantly higher at the 1 percent level than the two smallest classes, and significantly higher at the 5 percent level than the 13.1 to 14.5 inch class. The results of this study demonstrate that signifi- cantly higher yields of sap and sugar are obtained from trees having larger diameters than from those with smaller 33 THREE-YEAR TOTAL SAP AND SUGAR BY D. B. E. CLASSES 17 16 15 III» E E 58m ho 8.50% 0 9 8 7 IO 5 u“. 3 2 1 13 12 11 10 IIIIIIIIII SAP IIIIIIIIIIIIIII SW 700 11.6-13.0 =-==.======_==-=======§§=====2:========= 9.6; 11.5 600 500 #00 300 200 100 o a E a .m0 830% 14.6-19.8 13.1-1k.5 DIAMETERCLASSESUINCHES FIGURE 6 34 TABLE 3. F values for differences in sap and sugar yields between trees of different d.b.h. classes. Each analysis was based on 3 d.f. for diameter classes; 10 for replications; 30 for error; and 42 for total. Year of . between size class variance Product . F-ratio = . production error variance sap 1953 4.86** sap 1954 0.54 sap 1955 5.01** sap 1953—1955 2.97* sugar 1953 7.02** sugar 1954 0.61 sugar 1955 7.10** sugar 1953-1955 4.26* * Significant at 5% level ** Significant at 1% level 35 ma.m mm.m em.mH om.ma mm.aa ev.aa mo.HH mmummma ummsm mm.a me.a o¢.v mm.o Hm.v mo.m em.m mmma Cmmsm III: III. ma.¢ 4m.m mm.¢ mm.¢ mm.¢ emma ummsm mm.a mm.o mm.m mm.v Hm.m mm.m mo.m mmma Cmmsm In: Hma mom omo mmm Ham Hmm mmammma Cam an mm eam new mom oma mma mmma Cmm nu: In- mam ovm mma oom Hmm amma Cam ma mm HmH 46H Hma ems moa mmma Cmm Hm>mH Ho>mH IIIIIIIIIIIIII own mom m C50 IIIIIIIIIIIII as as. a a a pm mGMOE mmflOCH MOSOGH mmfiofifl MOSUGH mammmao mmmmmao m.ma m.¢a o.ma m.HH coauoseoua cmmzumn Ham no.4H -H.ma um.aa no.m 0 saw someone mUCoHommHo m w quUHmHCmHm "mo AquHos ummoHQv mumpoEmHo unmoq CuHB moouu Eoum moHon Hmmsm oCm mom I. whom» uCoHommHo CH A.£.Q.ov mommmHo HouoEMHo uCoHommHo Mom .oouw mom .moCCom CH moHlo Hmmsm oCm mom .v mamma 36 diameters. There is also indication (see Table 4) that the increase in sugar production is not attributed only to the increase in volume, but also to the higher percentage of sugar in the sap of trees with larger diameter. 37 EFFECT OF BASAL AREA ON THE YIELDS OF MAPLE SAP AND SUGAR The squares of d.b.h. of each of the 52 trees were calculated in order to represent the approximate value for the basal area. These values were included in a simple correlation analysis to show how their correlation coefficients compare with those of d.b.h. in regards to the yields of sap and sugar. Tables 1 and 2 show the extent and the significance level of correlation between the basal area and the sap and sugar yields for three seasons and their combined total. It appears that the correlation coefficients of the basal area are almost identical with those of d.b.h. and that the levels of significance of the two factors are exactly the same. Significant correlation exists between the basal area and the sap and sugar yields only so long as the d.b.h. itself is significantly correlated. In other words, the effect of the basal area of a tree on the yields of sap and sugar is none other\than that already expressed by its diameter. To determine whether the correlation coefficients of d.b.h. and basal area with tfiua sap yield are significantly different from each other, a t—test is required. The pro- cedure is as follows: 38 r = .419 = correlation coefficient between d.b.h. and sap yield for 3-year period (see Table 1). r2 = .428 = correlation coefficient between basal area and sap yield for 3-year period (see Table 1). 1 - Ii 1 ‘ r: S = Sr = r1 n-2 2 n-2 1 - (.419)2 1 - (.428)2 - '824 = __:_8_]_-Z. _ 7.070 7.070 = .118 = .117 S (r -r ) =JS 2 ‘I' S 2 l 2 r1 r2 j/r (.118)2 + (211712 = V'0276 = .166 39 S(r -r2) .419 - .428 .116 The difference between the correlation coefficients of d.b.h. and basal area with the sap yield was not signifi- cant. To be significant, the computed t at the 5 percent level and 50 d.f. must have the value of 2.0. In order to determine whether the inclusion of basal area in a simple correlation analysis brought forth better results in predicting sugar yield than if d.b.h. data alone were employed in such analysis, the same procedure, as before, is followed: r1 = .499 = correlation coefficient between d.b.h. and sugar yield r = .512 = correlation coefficient between basal area and sugar yield 40 I—‘N N 1 - r l ‘ r2 = -751 = .738 7.070 7.070 = .106 = .104 s - s 2 + s 2 (r1 r2) r1 r2 = \/(.106)2 + (.104)2 =V.0221 = .148 t = r1 ‘ r2 = .499 - .512 = 088 s .148 ° (r -'r I l 2 The difference between the correlation coefficients of d.b.h. and basal area with sugar yield is, therefore, not significant. 41 EFFECT OF THE TREE HEIGHT ON THE MAPLE SAP AND SUGAR YIELDS In an effort to show what correlation exists between tree height and the production of sap and sugar, a simple correlation analysis was conducted in which the yields of 52 trees for three seasons and their combined total were included. From Table 1 it appears that a consistent negative correlation exists between tree height and the sap and sugar yields, although it was not significant for any one season or for the three-year total. The magnitude (negative) is higher with sugar than with sap. There are indications that the increased total height of a maple tree has a depressing effect on both sap and sugar production, but with greater extent on the latter. However, the decrease in the sap and sugar yields due to increased tree height was not significant in any of the three study years. While this observation substantiates the results obtained in previous work (22), further experiments specifi— cally designed along this line are needed in order to show the exact effect of tree height on the yields of sap and sugar. 42 EFFECTS OF TREE VOLUME ON THE YIELDS OF SAP AND SUGAR The approximate tree volume was computed by multi- plying the square of d.b.h. by the total height. In this experiment, no conversion factor was used to correct for the taper of the bole, because the degree of taper was assumed to be constant for all the trees studied. Values thus obtained for each of the 52 trees were included in a simple correlation analysis to determine the effect that tree volume has on the yields of sap and sugar. Correlation coefficients and the level of significance appear in Tables 1 and 2, respectively. This correlation, while positive, is much less significant than either of those pertaining to d.b.h. or basal area. Undoubtedly, this reduction in the level of significance is due to the depressing effect of the tree height which is a vital component of the volume. Significant increases in yields of sap and sugar are expected as tree volume increases. It is evident that this favorable effect is attributed to the part d.b.h. contributes to the increase in volume of a particular tree rather than its total height. 43 EFFECT OF CROWN LENGTH ON THE MAPLE SAP AND SUGAR YIELDS Crown lengths of 52 trees, along with their yields of sap and sugar for three seasons and their total were in- cluded in a simple correlation analysis. From Table 2 it appears that no significant correlations exist between the crown length of maple trees and their sap and sugar production. No significant increases in the yields of sap and sugar are, therefore, expected from increased crown length of the trees in this experimental area. It appears that an increase in tree foliage due to increased crown length does not result in a significant increase in photosynthetic activity. This is attributed to the fact that the dense crown canopy in this woodlot limits the amount of solar radiation reaching the lower strata of the tree foliage and is not sufficient to bring about signi- ficantly greater production of carbohydrates. 44 EFFECT OF LIVE CROWN RATIO ON THE MAPLE SAP AND SUGAR YIELDS Live crown ratio is the proportion of the crown length to the total height of a tree, and it is, therefore, obtained by dividing the former by the latter and then multiplying the product by 100. The correlations in the three study years were positive but non-significant. The correlations involving sugar yield and live-crown ratio were also positive. These latter correlations were not significant except in 1955, when the relation was significant at the 5 percent level. To restate this in words rather than statistical terms, live crown ratio had no discernible effect on sap yield but may have had a slight effect on sugar yield. 45 EFFECT OF CROWN DIAMETER ON THE MAPLE SAP AND SUGAR YIELDS Yields of sap and sugar for three seasons and their total were included in a simple correlation analysis to deter- mine how they are correlated with the crown diameter. Data in Table 1 show that positive correlation exists between crown diameter and the sap and sugar yields. Although in only one season (1955) was the crown diameter significantly correlated with sap yield (see Table 2), it was very close to being significant in the 1953 season as well as for the com- bined three-year sap yield. With sugar yields, on the other hand, crown diameter was found to be significantly correlated in 1953, 1955, as well as for the three-year total. In order to determine the degree of variation between sap and sugar yields in trees of different crown diameter classes, analysis of variance was carried out. From the 52 trees originally used in this study, 42 were selected at random to represent three crown diameter classes, each with 14 trees. Table 5 presents the F—ratios between yields of sap and sugar, with the level of significance indicated for each season. This, along with Table 6 reveals that the larger crown diameter is associated with significantly higher yields than the smaller classes in all the three years studied. 46 It is also shown that, for both sap and sugar, the yields from trees with larger crown diameters are very significantly higher than yields from trees with smaller crown diameters in the 1953 season and in the three-year period. The yields of sap and sugar for the three-year period are presented graphically by crown classes in figure 7. Significant increases in the yields of sap and sugar are obtained from trees with larger crown diameters than from those with smaller crown diameter. This study also shows that the influence of larger crown diameter is equally effective in increasing sugar production and sap yields. 47 TABLE 5. F-values for differences in sap and sugar yields between trees of different crown diameter classes. Each analysis was based on 2 d.f. for crown classes; 13 for replications; 26 for error; and 41 for total. Year of . between size class variance Product . F-ratio , production error variance sap 1953 5.88** sap 1954 3.42* sap 1955 4.61* sap 1953-1955 6.53** sugar 1953 6.40** sugar 1954 3.50* sugar 1955 5.22* sugar 1953-1955 5.97** * * Significant at 5% level * Significant at 1% level 48 ma.m am.m em.ma mm.oa om.oa m¢.oa mmummma ummsm HH.N so.a mm.¢ oa.m mm.m mm.m mmma ummsm I--- mm.a No.4 mm.m ma.m m~.¢ amma Hmmsm mm.a om.o mm.m av.v mm.m mm.m mmma nmmsm oma mma cam mam mav New mmummma Cmm mm om mom «mm oma sea mmma Cam I- am mom Hem moa mma vmma Cmm mm mm mma mma mHH NHH mmma Cmm Ho>mH Ho>oH RH Rm IIIIIIIII moup Mom moCsom IIIIIIII um mCmoE Coauosooum mommMHo mommmHu umwm umom poem mm Ham? uUCooum ammzuma Ham meuam omumm «mumfi moCoHommHo quonHCmHm "mo muoumEmHo C3ouo QHHB mommy ummmq Eoum moHoH> Amman oCm mom mumoh uCoHommHo CH mommmHo CouoEMHo C3ono HCmuommHo How .oouu Mom .moCCom CH moHon Hmmsm oCm mmm .o mqmda ’0 r5 1+9 THREE-YEAR TOTAL SAP AND SUGAR BY CRWN DIAMETER CLASSES 1? 16 E E gm Mo 8238 0 3 m u 0 98 7 6 5h. 3 2 l _ SAP SUGAR 700 E mam a .mo 850m 31.- 1+8 30 25- 16- 2|: CRWNDIAMEMCLASSESHFEEE‘ FIGURE 7 50 EFFECT OF CROWN AREA ON THE YIELDS OF MAPLE SAP AND SUGAR The squares of the crown diameter, as an approximate value of the crown area, of 52 trees were included in a simple correlation analysis to determine the degree of correlation between crown area and the yields of sap and sugar. Table 1 shows that positive correlation exists be- tween crown area and the yields of sap and sugar. There was no significant correlation between crown area and sap yields. The same table shows that the correlation between the crown area and sugar yield is as significant as that between crown diameter and sugar production. Crown area of a sugar maple tree has approximately the same significant effect on the yield of sugar as that of crown diameter. Although positive, the correlation between crown area and the sap yields was not significant. 51 COMBINED EFFECT OF D.B.H., HEIGHT, CROWN DIAMETER, AND LIVE CROWN RATIO ON THE YIELDS OF MAPLE SAP AND SUGAR In an effort to determine the combined effect of d.b.h., height, crown diameter, and live crown ratio on the yields of sap and sugar for 52 trees for the three-year period (1953-1955), a multiple correlation analysis was conducted. From Table 7 the following relationships are noted: A. The expected yield of sap or sugar can now be pre- dicted, using a multiple regression equation (sometimes called the prediction equation) as follows: 2 = A + blxl + b2x2 + b3x3 + b4x4 i s; where Y = expected yield A = Y intercept on x bi = partial regression coefficients xi = tree characteristics (d.b.h., height, etc.) S; = standard error of estimate. To illustrate, let us assume that a particular tree in Baker WOodlot has the following characteristics: 52 mO.H HH.H mo.H mo.H mHm. mom. mm.v go. mo. OH.I HH. mm.m Hmmsm no.NH ¢N.mH mv.NH mm.H» mmH. mmw. hhH hm.v Ho.H nv.m| dm.m @Hm mom % mm m Im «9 mg mg HQ « f r OHHMH o m m CBOMU HouoEMHo OH\ H t 1 n.t r e o>HH CBOHU uanon .£.Q.o .x Co n t o n e t e a .1 e a ammo AmoCComV .1 n e_u.1 d m "Co oHon may mo COHmmonmm HmuCa .m m 1m. 1 .m m. .u . 0.05603 a m... u ma .m a a. e.t 1 r e a 20 % ®.m m w w &.M mo mHCoHUHmmoOU COHmmonoH HMHuHflm moouu mm mo moHon Hmmsm oCm mmm HMHOH Hmohlm Co Comma .mHmSHmCm CoHHMHoHHou mHmHHHCE 0:“ mo kaEECm .5 mqmda 53 d.b.h. = 15.0 inches height = 80.0 feet crown diameter = 30.0 feet live crown ratio 60.0 percent Insertion of these data and factors from Table 7 results in a prediction equation for the sap yield of this tree as follows: 2 = 216 + 3.54(150) - 2.47(80) + 1.01(30) + 4.97(60) ; 177 = 216 + 531 - 198 + 30 + 298 l 177 = 700 to 1054 pounds of sap for a three-year period, or 233 to 351 pounds annually. Likewise, sugar production of the same tree is predicted as follows: i 2.59 + .11(150) - .10(30) + .05(30) + .04(60) 1 4.33 2.59 + 16.50 - 8.00 + 1.50 + 2.40 l 4.33 10.66 to 19.32 pounds of sugar for a three—year period, or 3.55 to 6.44 pounds annually. B. The multiple correlation coefficients, R, for sap and sugar were found to be significant at 1% and .1% levels, respectively. C. The coefficients of determination, R2, for maple sap and sugar in this woodlot are 19.3% and 31.9%, respectively. 54 This means that only about 19% of the sap and about 32% of the sugar yields are determined by the four tree character- istics studied. The remaining variability in sap and sugar yields is subject to genetic, soil, climatic and unknown factors (2_). The coefficients of determination for a definite set of factors vary from one place to another depending upon the conditions of sugar bushes in different locations. Morrow (22) reports that live crown ratio and crown diameter com- bined accounted for 21 percent, 8 percent, and 38 percent of the variation in sugar percentage in three different sugar bushes with various degrees of crown closure. D. This multiple correlation analysis was employed in the hope of obtaining better results for the prediction of sap and sugar yields than by employing a simple correlation involving data pertaining to d.b.h. only. In order to show whether this objective was achieved, a t-test is necessary. Computations for this test are as follows: r1 = .419 = correlation coefficient between d.b.h. and sap yield (see Table 1) r2 = .439 = multiple correlation coefficient of four factors with sap yield (see Table 7). 55 2 2 1 - r1 1 - r Sr = Sr = 2 1 n-2 2 n-2 1 - 1.419)2 1 - (.439)2 = V/(Jls)2 + (.114)2 V°0265 .163 t =.1:2_:1:; = .419 - .439 = .122 S(r _ r ) .163 1 2 The difference between the multiple correlation coefficient (with four factors) and the correlation coefficient of d.b.h. with sap yield was not significant. To be signifi- cant, the computed t at 5 percent level and 50 d.f. must have the value of 2.0. The same procedure is followed to determine whether a significant improvement in predicting sugar yield was obtained by the multiple correlation analysis than by empl invo 56 oying a simple correlation involving d.b.h. data only. .499 = correlation coefficient of d.b.h. with sugar yield. .565 = multiple correlation coefficient of four factors sugar yield. 1 — ri l ‘ r: Sr = Sr = 1 n—2 2 n-2 1 - (.499)2 1 - (.565)2 = .106 = .096 =‘VQ.106)2 + (.096)2 V.0204 = .143 r1 ' r2 .499 - .565 t = -———————' = = .461 .143 (rl-rz) The difference between multiple correlation analysis 1ving four factors and a simple correlation involving d.b.h. in predicting sugar yields is not significant. pert The yields of sap and sugar can be predicted from data aining to d.b.h., height, crown diameter and live crown 57 ratio of the sugar maple trees. However, the prediction formula, due to a large margin of error expressed by the standard error of estimate, is of little use. The d.b.h., height, crown diameter, and live crown ratio are significant factors in determining the yields of sap and sugar, even though they account only for 19% of sap and for about 32% of the sugar yields. 58 SUMMARY AND CONCLUSIONS This study was designed to determine the relationship which exists between tree characteristics namely, d.b.h., basal area, height, volume, live crown ratio, crown length, crown diameter, and crown area, on the one hand, and the yields of sap and sugar on the other. Tree measurements for 52 trees relative to the eight tree characteristics were made in 1952. Maple sap and sugar yields of these trees were gathered for three consecutive seasons (1953 through 1955). The experimental area is located in Baker WOodlot on the campus of Michigan State University. In order to obtain maximum information about the effect of tree characteristics on the yields of sap and sugar, the following three statistical procedures were conducted: (1) Analysis of variance, in which the difference in sap and sugar means of d.b.h. and crown diameter classes were tested. (2) Simple correlation analysis, to determine the correlation that exists between each of the eight tree characteristics and the yields of sap and sugar. (3) Multiple correlation analysis, which included measurements of d.b.h., height, live crown ratio, and crown diameter, as well as sap and sugar yields for the 3-year period. The objectives 59 from the last analysis were: (A) To determine how much (in percent) of sap and sugar was influenced by the four tree characteristics involved. (B) To determine whether the multiple correlation analysis including four tree character- istics will bring about superior results in predicting the yields of sap and sugar than a simple correlation analysis with d.b.h. data only. Upon the completion of the different analyses discussed above, the following conclusions were derived: 1. Significant increases in the yields of sap and sugar are obtained from trees with larger diameters (d.b.h.) compared to those with smaller diameters. There are indi- cations that the increase in sugar production is not attributed only to the increase in the volume of sap produced, but also to the higher sugar percentage in the sap of trees with larger diameters. 2. Significant increases in sap and sugar yields are obtained from the increased basal area of a tree. However, this increase is none other than that already expressed by d.b.h. 3. Consistent negative correlation existed between tree height and the yields of sap and sugar in the three study years, but this correlation was not significant. It will be 60 worth-while to further investigate the effect of tree height in an experiment specifically designed for this purpose. 4. Significant increase in the yields of sap and sugar are expected by the increased tree volume. This increase is attributed to the part which d.b.h. contributes to the increase in volume rather than to the effect of height. 5. No significant increase in the yields of sap and sugar are expected from increased crown length of a tree in this experimental area. 6. Live crown ratio was positively correlated with the yields of sap and sugar in all the three study years, but this relation was not significant except with sugar yield in 1955. Therefore, no significant increase in the yield of sap is expected by a higher live crown ratio of maple tree. However, significant increase in sugar yield may be obtained with a larger live crown ratio. 7. Significant increases in the yields of sap and sugar are obtained from trees with larger crown diameters than from trees with smaller ones. This experiment also shows that large crown diameter is equally effective in increasing sap and sugar yields. 8. Large crown area of sugar maple trees significantly increases the yields of sugar. Although crown area and sap 61 yields are positively correlated, the correlation is not significant. 9. The d.b.h., crown diameter, and live crown ratio are significant factors in the production of sap and sugar. These three factors, along with the total height which has a depressing effect on both sap and sugar yields, determine 19 percent of the sap yield and 32 percent of the sugar yield in this experimental woodlot. 10. From yield data relative to the four tree character- istics, it is possible to predict the yields of sap and sugar for any given tree. However, due to the large standard error of estimate for both predicted sap and sugar, the importance of the prediction formula is much minimized. 11. No significant improvement was achieved in predicting sap and sugar yields by a multiple correlation analysis in- volving four tree characteristics than by a simple correlation using d.b.h. data only. 12. Since the four visual tree characteristics, namely d.b.h., height, crown diameter, and live crown ratio, deter- mine only about one—fifth of the sap yield and about one-third of the sugar yield for trees in this particular woodlot, it is of great importance to know what other factors determine the remainder of the sap and sugar yields of maple trees. Intensive research in the effects of soil characteristics and genetic variation is suggested for future study. It may provide the answer as to how important these two factors are in deter- mining sap and sugar yields. 62 10. 63 LITERATURE CITED Betts, H. S. 1945. Maple (Acer species). U.S. Forest Serv., Amer. weeds (Ser.). 12 pp. Bryan, A. H. 1910. Maple-sap syrup: its manufacture, composition and effect of environment thereon. U.S. Dept. Agr. Bur. Chem. Bull. 134. 110 pp. Bryan, A. H., Hubbard, W. F., and Sherwood, S. F. 1924. Production of maple sirup and sugar. U.S. Dept. Agr. Farmers Bull. 1366. 34 pp. Ching, T. M., and Mericle, L. W. 1960. Some evidence of premature stoppage of sugar maple sap production. Forest Sci. 6 (3): 270-275. Chittenden, A. K. 1919. Netes on maple syrup making. Mich. Agr. Exp. Sta. Quart. Bull. 1 (3). Collingwood, G. H., Cope, J. A., and Rasmussen, M. P. 1935. The production of maple sirup and sugar in New York State. N.Y. Agr. Col. (Cornell) Ext. Bull. 167, rev. 78 pp. Cool, B. M. 1957. An investigation of the effect of some production techniques and weather factors on maple sap and sugar yield in a central Michigan woodlot. Ph.D. thesis (unpublished), Mich. State Univ. 122 pp. Cope, J. A. 1944. Effect of grazing on maple sirup production. Jour. Forestry 42 (6): 460-461. . 1946. Silviculture of the sugar bush. Jour. Forestry 44: 647-649. Dambach, C. A. 1944 Comparative productiveness of adjacent grazed and ungrazed sugar maple woods. Jour. Forestry 42: 164-168. ' 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 64 Dunn, S., and Townsend, J. R. 1954. Propagation of sugar maple by vegetative cuttings. Jour. Forestry 52: 678-679. Edson, H. A. 1910. “Buddy sap"; a preliminary report upon the micro- organisms occurring in maple sap and their influence upon the quality of syrup. Vt. Agr. Exp. Sta. Bull. 151 pp. Eichmeier, A. H. 1955. weather and maple syrup. U.S. weather Bur., Weekly Weather and Crop Bull. 42 (3): 7—8. Henshaw, H. W. 1890. Indian origin of maple sugar. Amer. Anthrop. 3: 341-351. Herbert, P. A. 1923. Maple syrup making: two buckets per tree most profitable. Mich. Agr. Exp. Sta. Quart. Bull. 5 (2): 139-141. Hitchcock, J. A. 1937. The grazing of maple sugar orchards. Vt. Agr. Exp. Sta. Bull. 414. 14 pp. Huffman, R. E., DeVault, S. H., and Coddington, J. W. 1940. An economic study of the maple products industry in Garrett County, Maryland Univ. Md. Agr. Exp. Sta. Bull. 431. 52 pp. Jones, C. G., Edson, A. W., and Morse, W. J. 1903. The maple sap flow. Vt. Agr. Exp. Sta. Bull. 103. 144 pp. Jones, C. H., and Bradlee, J. L. 1933. The carbohydrate contents of the maple trees. Univ. Vt. and State Agr. Coll. Bull. 358. 147 pp. Kramer, P. J., and Kozlowski, T. T. 1960. Physiology of trees. McGraw-Hill Book Co., Inc., New York. pp. 317-319. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 65 Lawrence, J. E. 1953. Bigger sugar trees pay bigger. Farmers digest 17 (6): 49-50. (Condensed from New England Homestead.) Little, E. L., Jr. 1953. Check list of native and naturalized trees of the United States (including Alaska). U.S. Department Agr., Agr. Handb. 41. 472 pp. Marvin, J. W., and Greene, M. T. 1951. Temperature induced sap flow in excised stems of Acer. Plant Physiol. 26: 565-580. , and Erickson, R. O. 1956. A statistical evaluation of some of the factors responsible for the flow of sap from the sugar maple. Plant Physiol. 31: 57-61. . 1958. The physiology of maple sap flow. Chap. 6 in Thimann, K. V. (ed.), The physiology of forest trees. The Ronald Press Co. New York. McIntyre, A. C. 1932. The maple product industry of Pennsylvania. Pa. Agr. Exp. Sta. Bull. 280. 47 pp. Moore, H. R., Anderson, W. W., and Baker, R. H. 1951. Ohio maple syrup--some factors influencing produc— tion. Ohio Agr. Exp. Sta. Research Bull. 718. 53 pp. Morrow, R. R. 1952. Consistency in sweetness and flow of maple sap. Jour. Forestry 50: 130-131. 1955. Influence of tree crowns on maple sap production. Cornell Agr. Exp. Sta. Bull. 916. 30 pp. Naghski, J., and Willits, C. O. 1955. Maple sirup. 1X. Microorganisms as a cause of premature stoppage of sap flow from maple tap holes. Appl. Microbiol. 3: 149-151. Nearing, H., and Nearing, S. 1950. The sugar maple book. The John Day Co., New York. 271 pp. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 66 Robbins, P. W. 1949. Production of maple syrup in Michigan. Mich. State Coll. Agr. Exp. Sta. Circ. Bull. 213. 28 pp. Sears, P. B. 1943. Grazing versus maple syrup. Science Newsletter 44 (7): .105. Sheneman, J. M., Costilow, R. N., Robbins, P. W., and Douglass, J. E. 1958. ‘ Correlation between microbial populations and sap yields from maple trees. Food Research 24 (1): 152-159. Snow, A. G. 1939. Chemically induced rooting of sugar maple cuttings. U.S. Dept. Agr., Forest Service, Nertheast Forest Exp. Sta. Tech. NOte 27. 1 p. mimeo. (not seen). Stevens, C. L., and Dunn, S. 1943. Increasing the sugar content of sugar maples. Jour. Forestry 41: 922. , and Eggert, R. L. 1945. Observations on the causes of the flow of sap in Red maple. Plant Physiol. 20: 636-648. Stevenson, D. D., and Bartoo, R. A. 1940. Comparison of the sugar percent of sap in maple trees growing in open and dense groves. Pa. State Forestry School Research Paper 1, August 29, 1940. 3 pp. Taylor, F. H. 1953. Operation of an experimental sugar bush. Proc. Second Confer. Maple Products. Eastern Utilization Research Branch, Agr. Research Serv., U.S.D.A., Philadelphia. . 1956. Variation in sugar content of maple sap. Vt. Agr. Exp. Sta. Bull. 587. 39 pp. United States Department of Agriculture, 1956. Agri- culture statistics. 1955. 610 pp. 42. 43. 44. 45. 67 U.S. Department of Agriculture and Michigan State Department of Agriculture (Michigan Crop and Live- stock Reporting Service). 1 p. mimeo. May 12, 1960. White, D. P., and Robbins, P. W. 1958. Effect of chemical fertilization on the yield of maple sap and sugar. Unpublished report, Forestry Dept., Michigan State University. White, w. E., Stevenson, D. D., and Triebold, H. 1941. The comparative sugar content of the sap of sugar maples growing in the open and in forest stands. Pa. Agr. Exp. Sta. Bull. 414: 21-22. Willits, C. O. 1958. Maple-sirup producers' manual. U.S. Dept. Agr., Agr. Handb. 134. 80 pp. APPENDIX 68 APPENDIX ANALYSIS 1. Maple sap yields for the 1953 season and diameter (d.b.h.) classes Table of Means: d.b.h. classes — inches/10 < 115 116-130 131-145 > 145 Means (pounds) 104.73 127.27 126.64 163.55 Standard deviation of the mean = 11.05 General mean = 130.55 Analysis of Variance Table: Source DF Sum of squares Variance F Total 43 79020.905 Repl. 10 19113.412 Classes 3 19597.275 6532.426 4.862 Error 30 40310.217 1343.677 Computations for the comparison between yields for d.b.h. classes, using Studentized Range Test and standard deviation of the mean: At 1% level: DF (2) (3) (4) Table value 3.89 4.06 4.16 Standard dev. mean 11.05 11.05 11.05 Least sig. diff. 42.98 44.86 45.97 At 5% level: (2) (3) (4) 2.89 3.04 3.12 11.05 11.05 11.05 31.93 33.59 34.49 69 ANALYSIS 2. Maple sap yields for the 1954 season and d.b.h. classes Table of means: d.b.h. classes - inches/10 < 115 116-130 131-145 > 145 Means (pounds) 237.09 199.64 198.73 240.18 Standard deviation of the mean = 31.10 General mean = 218.91 Analysis of variance table: Source DF Sum of squares Variance F Total 43 606829.625 Repl. 10 270508.131 Classes 3 17180.363 5726.791 0.538 Error 30 319141.131 10638.041 70 ANALYSIS 3. Maple sap yields for the 1955 season and d.b.h. classes Table of means: d.b.h. classes - inches/10 < 115 116-130 131-145 > 145 Means (pounds) 185.45 190.18 202.82 276.64 Standard deviation of the mean = 19.01 General mean = 213.77 Analysis of variance table: Source DF Sum of squares Variance F Total 43 218431.719 Repl. 10 39446.230 Classes 3 59733.182 19911.064 5.009** Error 30 119252.307 3975.074 Computations for the comparison between yields for d.b.h. classes, using Studentized Range Test and standard deviation of the mean: At 1% level: D.F. (2) (3) (4) Table value Standard dev. Least sig. 3.89 4.06 4.16 mean 19.01 19.01 19.01 difference 73.91 77.14 79.04 At 5% level: (2) 2.89 19.01 54.94 (3) 3.04 19.01 57.79 (4) 3.12 19.01 59.31 71 ANALYSIS 4. Maple sap yields for three-year period (1953-55) and d.b.h. classes Table of means: d.b.h. classes - inches/10 < 115 116-130 131-145 > 145 Means (pounds) 527.27 517.09 528.18 680.36 Standard deviation of the mean = 45.44 General mean = 563.23 Analysis of variance table: Source DF Sum of squares Variance F. Total 43 1457677.710 Repl. 10 574202.724 Classes 3 202074.455 67538.153 2.966* Error 30 681400.542 22713.348 Computations for the comparison between yields for d.b.h. classes, using Studentized Range Test and the standard deviation of the mean: At the 5% level: D.F. (2) (3) (4) Table value Standard dev. 2.89 3.04 3.12 mean 45.44 45.44 45.44 Least sig. difference 131.32 137.14 140.77 72 ANALYSIS 5. Maple sugar yields for the 1953 season and d.b.h. classes Table of means: d.b.h. classes - inches/10 < 115 116-130 131-145 > 145 Means (1bs./100) 265.45 339.27 351.09 481.55 Standard deviation of the mean = 33.91 General mean = 359.34 Analysis of variance table: Source DF Sum of squares Variance F Total 43 828229.895 Repl. 10 182364.637 Classes 3 266413.342 88804.446 7.021** Error 30 379451.906 12648.396 Computations for the comparison between yields for d.b.h. classes, using Studentized Range Test and the standard deviation of the mean: At 1% level: D.F. (2) (3) (4) Table value 3.89 4.06 p 4.16 Standard dev. mean 33.91 33.91 33.91 Least sig. difference 121.91 137.67 140.07 At 5% level: (2) (3) (4) 2.89 3.04 3.12 33.91 33.91 33.91 98.00 103.09 105.80 ANALYSIS 6. 73 Maple sugar yields for the 1954 season and d.b.h. classes Table of means: d.b.h. classes - inches/10 < 115 116—130 131-145 < 145 Means (lbs./100) 482.10 439.45 423.27 554.10 Standard deviation of the mean = 75.00 General mean = 474.73 Analysis of variance table: Source DF Sum of squares Variance F Total 43 3228552.746 Repl. 10 1259834.724 Classes 3 112690.003 37563.338 0.607 Error 30 1856026.956 61867.599 74 ANALYSIS 7. Maple sugar yields for the 1955 season and d.b.h. classes Table of means: d.b.h. classes - inches/10 < 115 116-130 131-145 > 145 Means (1bs./100) 354.36 368.55 420.82 639.09 Standard deviation of the mean = 49.57 General mean = 445.70 Analysis of variance table: Source DF Sum of squares Variance F Total 43 1496987.169 Repl. 10 210642.904 Classes 3 575457.337 191819.116 7.097** Error 30 810886.907 27029.567 Computations for the comparison between the yields for d.b.h. classes, using Studentized Range Test and the standard deviation of the mean: At 1% level: D.F. (2) (3) (4) Table value 3.89 4.06 4.16 Standard dev. mean 49.57 49.57 49.57 Least sig. difference 192.83 201.25 206.21 At 5% level: (2) (3) (4) 2.89 3.04 3.12 49.57 49.57 49.57 143.26 150.51 154.66 75 ANALYSIS 8. Maple sugar yields for three-year period (1953- 1955) and d.b.h. classes Table of means: d.b.h. classes - inches/10 < 115 116—130 131-145 > 145 Means (1bs./lOO) 1101.91 1147.27 1195.18 1690.18 Standard deviation of the mean = 132.50 General mean = 1283.64 Analysis of variance table: Source DF Sum of squares Variance F Total 43 11602151.863 Repl. 10 3337920.288 Classes 3 2471955.854 823985.637 4.268* Error 30 5792275.720 193075.705 Computations for the comparison between yields for d.b.h. classes, using Studentized Range Test and the standard deviation of the mean: At 5% level: D.F. (2) (3) (4) Table value Standard dev. At 1% level: mean Least sig. difference 2.89 132.50 382.92 (2) 3.89 132.50 515.42 3.04 132.50 402.80 (3) 4.06 132.50 537.95 3.12 133.59 413.40 (4) 4.16 132.50 551.20 76 PQIAJJYSIS 9. Maple sap yields for the 1953 season and crown diameter classes Table of means: Crown classes - in feet < 25 25-30 > 30 Mean (pounds) 112.29 115.64 155.29 Standard deviation of the mean = 9.87 General mean = 127.74 Analysis of variance table: Source DF Sum of squares Variance F Total 41 75710. 115 Repl. 13 24255.448 Classes 2 16015. 186 8007. 596 5.875** Error 26 35439.481 1363.058 -1__ Computation for the comparison between yields for crown diameter classes, using Studentized Range Test and the standard deviation of the mean: At the 1% level: D.F. (2) (3) Table value 3.93 4.11 Standard dev. mean 9.87 9.87 Least sig. difference 38.79 40.57 At 5% level: (2) (3) 2.91 3.06 9.87 9.87 28.72 30.20 77 PQIAIJYSIS 10. Maple sap yields for the 1954 season and crown diameter classes Table of means: Crown classes - in feet < 25 25-30 > 30 Mean (pounds) 192.64 167.93 267.00 Stuaridard deviation of the mean = 27.90 General mean = 209.19 Analysis of variance table: SCJUtrce DF Sum of squares Variance F Total 41 551598.468 Rapl. 13 193890.476 Cldasses 2 74456.332 37228.169 3.417* Error 26 283251.660 10894.294 Computations for the comparison between yields for crown diameter classes, using Studentized Range Test and the standard deviation of the mean: At the 5% level: D.F. (2) (3) Table value 2.91 3.06 Standard dev. mean 27.90 27.90 Least sig. difference 81.19 85.36 78 ANALYSIS 11. Maple sap yields for the 1955 season and crown diameter classes Table of means: Crown classes - in feet < 25 25-30 > 30 Mean (pounds) 166.79 189.71 252.43 Standard deviation of the mean = 20.65 General mean = 202.98 Analysis of variance table: Source DF Sum of squares Variance F Total 41 244982.973 Repl. 13 45718.976 Classes 2 55036.333 27518.170 4.609* Error 26 155227.663 5970.298 Computations for the comparison between yields for crown diameter classes, using Studentized Range Test and the standard deviation of the mean: At the 5% level: D.F. (2) (3) Table value 2.91 3.06 Standard dev. mean 20.65 20.65 Least sig. difference 60.09 63.19 At the 1% level: (2) (3) 3.93 4.11 20.65 20.65 81.15 84.87 79 ANALYSIS 12. Maple sap yields for three-year period (1953-1955) and crown diameter classes Table of means: Crown classes - in feet < 25 25-30 > 30 Mean (pounds) 471.71 472.57 674.71 Standard deviation of the mean = 45.76 General mean = 539.67 Analysis of variance table: Source DF Sum of squares Variance F Total 41 1623715.356 Repl. l3 478507.331 Classes 2 383000.192 191500.096 6.532** Error 26 762207.807 29315.682 Computations for the comparison between yields of sap for three crown diameter classes, using Studentized Range Test and the standard deviation of the mean: At the 1% level: D.F. (2) (3) Table value 3.93 4.11 Standard dev. mean 45.76 45.76 Least sig. difference 179.84 188.07 At the 5% level: (2) (3) 2.91 3.06 45.76 45.76 133.16 140.03 ANALYSIS 13. 80 Maple sugar yields for the 1953 season and crown diameter classes Table of means: Crown classes - in feet < 25 25-30 > 30 Mean (pounds/100) 287.71 324.64 447.36 Standard deviation of the mean = 33.04 General mean = 353.24 Analysis of variance table: Source DF Sum of squares Variance F Total 41 797029.614 Repl. 13 204091.618 Classes 2 195572.334 97786.170 6.398** Error 26 397365.662 15283.292 Computations for the comparison between yields of sugar for three crown diameter classes, using Studentized Range Test and the standard deviation of the mean: At 1% level: D.F. (2) (3) Table value 3.93 4.11 Standard dev. mean 33.04 33.04 Least sig. difference 129.85 135.79 At 5% level: (2) (3) 2.91 3.06 33.04 33.04 96.15 101.10 81 ANALYSIS 14. Maple sugar yields for the 1954 season and crown diameter classes Table of means: Crown classes - in feet < 25 25-30 > 30 Mean (pounds/100) 523.29 365.93 597.43 Standard deviation of the mean = 64.44 General mean = 462.21 Analysis of variance table: Source DF Sum of squares Variance F Total 41 3045491.059 Repl. 13 1127125.745 Classes 2 406969.854 203484.927 3.500* Error 26 1511395.485 58130.593 Computations for the comparison between sugar yields for three crown diameter classes, using Studentized Range Test and the standard deviation of the mean: At the 5% level: D.F. (2) (3) Table value Standard dev. Least sig. 2.91 3.06 mean 64.44 64.44 difference 187.52 197.19 82 ANALYSIS 15. Maple sugar yields for the 1955 season and crown diameter classes Table of means: Crown classes - in feet < 25 25-30 > 30 Mean (pounds/100) 333.36 395.57 570.00 Standard deviation of the mean = 53.70 General mean = 432.98 Analysis of variance table: Source DF Sum of squares Variance F Total 41 1720802.964 Repl. l3 249714.975 Classes 2 421380.332 210690.166 5.219* Error 26 1049707.644 40373.373 Computations for the comparison between sugar yields for three crown diameter classes, using Studentized Range Test and the standard deviation of the mean: At the 5% level: D.F. (2) (3) Table value 2.91 3.06 Standard dev. mean 53.70 53.70 Least sig. difference 156.26 164.32 At 1% level: (2) (3) 3.93 4.11 53.70 53.70 211.04 220.91 83 ANALYSIS 16. Maple sugar yields for three-year period (1953— 1955) and crown diameter classes Table of means: Crown classes - in feet < 25 25-30 > 30 Mean (pounds/100) 1048.64 1090.14 1622.93 Standard deviation of the mean = 131.04 General mean = 1253.91 Analysis of variance table: Source DF Sum of squares Variance F Total 41 12354871.434 Repl. 13 3232209.358 Classes 2 2871805.910 1435908.276 5.973** Error 26 6250846.166 240417.742 Computations for the comparison between sugar yields for three crown diameter classes, using Studentized Range Test and the standard deviation of the mean: At 1% level: D.PK (2) (3) Table value 3.93 4.11 Standard dev. mean 131.04 131.04 Least sig. difference 514.99 538.57 At 5% level: (2) (3) 2.91 3.06 131.04 131.04 381.33 400.98 Fish: “3E 01:.“st ”VD. I” 1 W' e ‘ ' 1 ‘ V 5}! k, ...p. B \j.~J 5’) r MICHIGAN STATE UNIV. LIBRQRIES I“WU”WI”WV”WWWWIIIHIIIHIWHII 31293104096049