n-W'z-vi ' •rainage, Drought, Defoliation, and Death in Unmanaged Connecticut Forests G. R. Stephens and D. E. Hill GOVERNMENT PUBLICATIONS RECEIVED BULLETIN 718 OF THE CONNECTICUT AGRICULTURAL EXPERIMENT STATION, NEW HAVEN, APj(L||^9720 ]QJ] WILBUR CROSS LIBRARY UNIVERSITY OF CONN& UT Digitized by the Internet Archive in 2011 with funding from LYRASIS members and Sloan Foundation http://www.archive.org/details/drainagedroughtdOOstep Contents Summary 4 Introduction 5 The Forests 6 The Climate ,.„_ ......... 8 Defoliation .\: V .....: 8 Methods 9 Population - 10 Diversity 16 Birth and Death r 17 Single Stems 26 Basal Area ,^. 27 Distribution of Diameter 32 Growth - 34 Canopy Composition 39 Predicting Change 43 Drought, Defoliation, and Death 46 UNIVERSITY OF CONNECTICUT UBRAR* 3TORRS. CT. Acknowledgements We are indebted to S. Collins and the late A. R. Olson for par- ticipating in the 1959 survey and to D. B. Downs and L. E. Gray for assisting in 1970. We thank the State Park and Forest Commission, the White Me- morial Foundation, and E. C. Childs of Great Mountain Forest for the use of their woodlands for this study. Summary The natural changes during 1959-70 in four Connecticut forests were examined, related to defoliation, drought, and soil drainage, and compared to four other Connecticut woodlands previously studied. The forests ranged from young to old, moist to dry, and varied in amount of conifers present and in defoliation suffered. Population varied with stand age and disturbance; in 1959 it ranged from 592 to 1119 stems per acre. During 1959-70 population declined about one- tenth in three undisturbed tracts, but increased nearly two-thirds in one disturbed by defoliation and wind. Birth and death of trees were gen- erally unrelated to soil moisture. Birth declined, however, with increas- ing age in three undisturbed stands. Death, on the other hand, de- clined with decreasing population. Basal area, or bulk of the forest, ranged from 76 to 147 square feet per acre in 1959. Stands with many conifers had about 50 percent more basal area than those without. During 1959-70, basal area increased in all tracts. Accretion on persisting trees varied from 17 to 29 percent but showed no clear relation to soil drainage. Mortality varied from 5 to 10 percent of 1959 basal area and was also unrelated to drainage. Since ingrowth was a steady, 1 to 2 percent of persisting basal area, net in- crease depended chiefly on the balance between accretion and mortality. Considerable differences in growth and loss existed among species. In total, 24 major and 13 minor species were represented. The four forests were equally diverse in 1959 and their diversity decreased slight- ly during 1959-70. Composition of the canopy, however, changed little, and the forests looked nearly the same in 1970 as in 1959. Transitions during 1959-70 among species groups dominating one- eightieth-acre plots were obtained. For forests without conifers the transitions anticipate much maple and birch but little oak in the future. This is much the same as predicted for other hardwood forests observed lor 40 years. However, in forests with main' conifers, mostly hemlock, the anticipation is many conifers, few maple and birch, and almost no oak. Thus, some markedly different forests are predicted. Drought appeared to change mortality rate little. Repeated defolia- tion, however, increased mortality on all but poorly drained soils. Death ol major species was 2.3 pereenl annually in t\\ ice -defoliated moderate K and well drained sites compared to 15 pereenl in a once-defoliated dr) site and 1.3 percent in undefoliated stands. Oak, the prime target <>l defoliators, l<»st most: repeated defoliation increased its mortality about hall. Drainage, Drought Defoliation, and Dea in Unmanaged Connecticut Forests G. R. Stephens and D. E. Hil Introduction Several earlier reports (Collins 1962, Olson 1965, Stephens and Waggoner 1970) described the changes occurring during 30 to 40 years in four unmanaged mixed hardwood woodlands. The relations of population, change, and growth to soil moisture were examined. However, all the tracts lie within 13 miles of one another in central Connecticut and, unfortunately, the division of the sample among mois- tures classes is irregular. Three of the tracts are in the Meshomasic State Forest (Fig. 1); therefore, we shall refer to all of them as the Meshomasic tracts hereafter. • MESHOMASIC SERIES ESTABLISHED 1926-27 ONEW SERIES ESTABLISHED 1959-60 Fig. 1 Locations of the New tracts (open circles) described in this bulletin and the Meshomasic tracts (closed circles) described earlier (Stephens and Waggoner 1970). During 1959-60 sample transects were established in four widely separated forests on soils common in Connecticut. The new tracts were selected to sample over a greater area of Connecticut, to provide great contrast in age, climate, and drainage and to examine the in- fluence of these factors on change in the forest. 6 Connecticut Experiment Station Bulletin 718 Additionally, the selection afforded contrast of forests with few or main- conifers. Further, the trees that grew on the four tracts were subjected to varying degrees of drought and insect defoliation during the last decade. This report will summarize the changes that have oc- curred during the last decade, relate them to soil drainage, drought, and defoliation and compare them to changes observed during 40 years in the Meshomasic tracts. The locations of the new tracts are shown in Figure 1 and their characteristics are summarized in Table 1. Table I. Characteristics of the new tracts Age Climate Hardpan Conifers Defoliation Gay City Young Driest and warmest Natchaug Young Dry and warm Norfolk Older Wettest and coolest Catlin Wood Oldest Moist and cool No None Most Yes None None Yes Manx- None Weak Many Some The Forests The four tracts all lie in Connecticut's upland region of metamor- phic rocks and glaciated soils. Gay City and Natchaug, the relatively young woodlands, are in the eastern highlands; the older woodlands. Norfolk and Catlin Wood, are in the western highlands. The tracts vary in soil, climate', and history. The Gay City tract, in Gay City State Park, is a mixed hardwood woodland with few conifers. One portion, in Hebron, at an elevation of 550 to 600 feet occupies an east-facing slope that varies from 4 to 11 percent. The soils have formed on friable glacial till derived chiefly from Hollon schist. 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We also observed that the tracts contained a mixture of single stems and sprout clumps. Was the increase in number of stems due to new seedlings or increased sprouting? Single stems, as a percent of total stems, are shown in Table 9. For major species the proportion of single stems remained unchanged over all tracts and sites. How- ever, among major species the proportion of single stems increased in 3 and declined in 12 The change was usually small, suggesting that death and birth affected sprout clumps and single stems similarly. Change in proportions among drainage classes was also slight. Single stems increased on the moderately and well drained soils, but decreased on the poorly and somewhat excessively drained. During 1959-70 the proportion of single stems in minor species decreased from 47 to 30 percent of single stems. However, this de- crease occurred only on the poorly and moderately well drained sites. Slight increases were noted on the well drained and somewhat excessively drained soils. At Gay City, major species dropped from 67 to 58 percent of single stems, and the decrease occurred on all sites. Minor species also decreased, 46 to 30 percent, but only on the poorly and moderately well drained sites. Although the actual number of single stems in- creased for sugar and red maple, black birch, and beech, only sugar maple increased proportionately in single stems. Among the minor species, chestnut (which now arises only as sprouts) and flowering dogwood increased their proportion of single stems. At Natchaug the proportion of single stems scarcely changed for major species, 67 percent in 1959 and 65 in 1970, and decreased slight- ly for minor species, 33 to 26 percent. On the poorly drained soil the proportion of single stems was about half whereas it was nearly three- fourths on the moderately well drained soil. Only black birch and chestnut increased in actual number of single stems per acre. In Norfolk there was no overall change during 1959-70. Beech was the only species to increase in number of single stems per acre, primarily on the well drained soils. The proportion of single stems was greatest on the poorly drained soil and decreased as drainage1 improved. At Catlin Wood the birth of many hemlocks increased the propor- tion ol single stems among major species from 70 to 76 percent. We also noted that witchhaze] increased dining 1959-70. However, it must have been mainly through sprouting because the number of its single terns dropped from 60 to 42 per acre. The percentage of single stems over all minor species decreased From 70 to 32, Thus, we see thai increase in single stems oJ major species oc- Drainage, Drought, Defoliation, and Death 27 curred mostly at Catlin Wood and was due mainly to hemlock. The proportions of single stems scarcely changed at stable Norfolk or at Natchaug. However, in young Gay City the proportion of single stems decreased, suggesting more birth from sprouting than from seed or more death of single stems than of sprout clumps. Apparently sprout- ing had some advantage in that young stand, but not in the older. The proportion of single stems in the Meshomasic tracts was re- ported to be about two-thirds, and it remained near this level for 40 years (Stephens and Waggoner 1970). In the present study the pro- portions for major species are slightly greater, about 70 percent for all but the driest site (Table 9). However, this small increase is due to conifers in Norfolk and Catlin Wood. Actually, the proportion of single stems in Gay City and Natchaug, without conifers, is close to two-thirds. The conifers observed do not sprout, and the rare multiple stems usually result from injury. If conifers are plentiful, therefore, the proportion of single stems surely increases. If we ignore the conifers, the proportion of single stems among the remaining major species approaches the two-thirds observed in other stands and changes little with time. Thus, the same conditions affecting sprouting must have applied in all stands. Single stems of minor species generally decreased during 1959-70 on all tracts except Norfolk where they were rare. This is unlike the trend of increased proportion of single stems of minor species with time noted in the Meshomasic tracts. BASAL AREA Basal area, the cross-sectional area of the stem, indicates the size of individuals, whereas population simply enumerates the individuals in the forest. Basal area, summed over all stems, gives the bulk of the forest, but the basal area of a great many small stems is slight whereas that of even a few large stems is great. Therefore, basal area provides an alternative to population for naming or describing the forest. In 1959, Gay City had the smallest and Norfolk, with nearly twice the basal area, had the greatest bulk (Table 10). Despite decreasing population in all but Catlin Wood, basal area of all tracts increased during 1959-70. The increase averaged about 12 percent of 1959 basal area, ranging from 9 at Gay City to 17 at Catlin Wood. Increases were due almost entirely to major species; only in Catlin Wood did basal area of minor species increase. Change in basal area of both major and minor species on all tracts was generally unrelated to drainage class. Although poorly drained soils had the greatest gains in all but Gay City, there was no clear relation of other sites to gain. Basal area, however, increased on all drainage classes of all tracts except Gay City (Table 10). There it decreased about 2 percent on the moderately well drained soil. 28 Connecticut Experiment Station Bulletin 718 Table 10. Basal area in square feet per acre Major Species Site Catli Year Gay City Xatchaug Norfolk Wood All Poorly Drained 1959 81 60 145 152 113 1970 94 69 163 185 132 Mod. Well Drained 1959 73 91 155 85 101 1970 72 104 172 95 112 Well Drained 1959 73 139 193 131 1970 78 147 224 145 S. Excess. Drained 1959 1970 65 79 65 79 All 1959 73 81 147 130 109 1970 80 Minor 92 Species 162 151 123 Poorly Drained 1959 5.0 2.7 .9 1.9 1970 3.3 2.5 .7 1.4 Mod. Well Drained 1959 4.0 1.3 <-l .6 1.2 1970 2.9 1.3 <-l 1.5 1.3 Well Drained 1959 3.8 ,3 1.6 1970 4.0 2 1.7 S. Excess. Drained 1959 1970 .4 .3 .4 ,3 All 1959 3.4 1.8 <.l .(> 1.5 l')7() 2.S 1.7 <.l I.o 1,1 We see both striking similarities and differences among these tracts .Hid those reported earlier (Stephens and Waggoner, L970). For ex- ample, basal area of major species in Gay City and Natchaug in 1959 was similar to i lie 35- to 50-year-old stands <>l L937 in the Meshomasic tracts. The large basal area oi Norfolk and Catlin Wood was about 50 pex.nl greater than Gay City and Natchaug, and as we shall see. the addition was attributed to the conifers. Ml tracts ol this new series increased in basal area during L959 70. Among the Meshomasic tracts only Turkey Mill increased during L957-67. Drainage, Drought, Defoliation, and Death 29 In 1959 maples comprised 22 percent of basal area; birches, 14 percent; oaks, 27 percent; hemlock, 22 percent (Table 11). On the other hand beech, though numerous, contributed only 3 percent of basal area. During 1959-70 the proportions of basal area changed little; oaks decreased slightly, birch remained constant, while hemlock and maple increased slightly. Earlier, we called Gay City a maple-birch-oak forest by virtue of its population. However, in 1959 its basal area was 32 percent birch, 29 percent oak and 18 percent maple. During 1959-70 basal area of birch and maple increased slightly. Despite a nearly 50 percent de- crease in number of oak, its basal area declined only about 10 percent. Therefore, the tract remained nearly constant and might better be called a birch-oak-maple forest by virtue of its bulk instead of the maple-birch-oak name suggested by mere numbers of stems. Black birch comprises slightly more than half of birch basal area. It pre- dominates on the drier sites, whereas yellow birch prevails on the moister sites. Red oak supplies nearly half of oak basal area and it predominates on the moderately and well drained sites. White oak predominates on poorly drained and scarlet oak on the somewhat ex- cessively drained. Natchaug, too, was called a maple-birch-oak forest by population. However, in 1959, oak contributed 52 percent of basal area. Red oak supplied half and white oak more than a third of oak basal area. By 1970 the proportions were little changed. Oak decreased slightly to 50 percent; red oak increased while white declined. Red maple com- prised nearly all maple basal area and increased from 22 to 26 percent by 1970. Birches, primarily black, decreased slightly from 18 to 16 percent of basal area. Therefore, Natchaug is really an oak-maple-birch forest by bulk. Norfolk was called a hemlock -beech-maple-birch stand by popula- tion. In 1959 maple provided 35 percent, hemlock 28 percent, birch 7 and beech 6 percent of basal area. During 1959-70 maple decreased and hemlock increased slightly but others remained nearly unchanged. Thus, in terms of basal area, Norfolk is a hemlock-maple forest. Red maple predominates on the moister sites while sugar maple prevails on the well drained soil. Red oak supplied a fifth of basal area on the moderately well drained soils and an eighth on well drained. Catlin Wood was also described as a hemlock-beech-maple-birch forest by population. In 1959, hemlock provided 38 and oak 33 percent of basal area. Maple comprised 12, birch 8, and beech 3 percent of basal area. Although numerous, maple, birch and beech together con- tributed less basal area than the few large oaks present. By 1970, oak basal area decreased slightly while that of all others increased slightly. Thus, Catlin Wood was really a hemlock-oak forest. Hemlock, white oak and white pine predominated on the poorly drained soils. Hem- 30 Connecticut Experiment Station Bulletin 718 c? 01 01 01 n k w cm in t-; t- cm m co t- , •— — W i—l CS Ho, -- in t^ rvj ,_■ r|H CM 00 >> in CD 00 ' CI (D CD N < cd i — i — 1-1 -d o d 'rt O CO Tt* CO ^ O CD *j 2 t- Sqoj — 1 I- ' rH oo in in cd S CM CM cm i— 1 £ >» 2 > CD cm t> ■* "* CO t- o '« in t- -* in oo d CO w CD CD I CM CM CM rH V ■<* ■<* ^f p rH CO CO V i— I t- rj< 00 C r- 1 •— ] r— j cm ■<* V V V vv HOCOO r-j ' CM ^ ' CO V c-l ^1 i-< C i— ' i— I c , ' cm cm . 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W J? 0 S fc * 3 "3 *3 3 tfj o •- -^ 6 cu ii t- o o to -a c -^ - 5x^ 3rSr=] Drainage, Drought, Defoliation, and Death 31 133 H H H H 1(3 H H H H H H Tf iC 'vvv v vvvvH I 'vv 'vvvv v^ S CO V © CD H >-J CO OS vv v^ S oci >-h ih coh '-;'-; <~i oq CO 'V VV V^ o i—i CO O O "* i-J CCj i— J i-J ^ O] 'V V V ^ « 0 qQ ,_( _, iohoh O CT> CM v 'v **■ ■ § C« , >N *S rr-f CO ;§ -^ ^u E PQ r- & ffi O ^ £ co m l> <3 £ w E-. co 32 Connecticut Experiment Station Bulletin 718 lock, red maple, red and white oak prevailed on the moderately well drained soils and hemlock and red oak on the well drained soil. We see that although great changes in numbers of stems occurred during 1959-70 in some tracts, the change in basal area was small. Thus, these tracts appear much the same in 1970 as they did in 1959. The change we have noted in basal area is net change. To see how persistent trees grew and how much basal area was gained and lost through birth and death we must await the section, Growth. But first we examine Distribution of Diameter. DISTRIBUTION OF DIAMETER Population enumerates number of stems, and basal area presents their bulk. Together they indicate whether trees are generally small or large. However, to determine the proportion of trees of different sizes we divided them into four classes: small saplings, 0.5 to 1.5 inches d.b.h.; large saplings, 1.6 to 5.5; poles, 5.6 to 11.5; and sawtimber, greater than 11.5 inches d.b.h. As stands mature, major species will be in all classes, but rarely will the stems of minor species grow beyond large saplings. Although their populations differed in 1959, the proportion of major species in each size class was the same for Gay City and Natchaug (Table 12). Norfolk and Catlin Wood had proportionally Table 12. Percentage of major species by diameter Small Saplings Large Saplings Poles Sawtimber Tract 1959 1970 1959 1970 1959 1970 1959 1970 Gay City 43 42 40 36 15 19 o 3 Natchaug 41 34 41 •42 15 17 3 7 Norfolk 17 19 49 45 28 28 6 8 Catlin Wood 28 48 42 32 18 12 12 8 All 33 37 43 38 L9 IS 5 7 fewer saplings and more pole and sawtimber stems than Gay City and Natchaug. This is not unexpected in the older Norfolk and Catlin Wood. Norfolk had almost no minor species, but in 1959 on the other tracts minor species constituted a fourth to a third of all stems, mostly small saplings. During 1959-70 the proportions ol poles and saw t imber remained unchanged or increased on all bul Catlin Wood where they decreased (Table 12). The increased proportion at Cay City resulted from fewer saplings ; actually the number ol poles and sawtimber stems scarceh Drainage, Drought, Defoliation, and Death 33 changed. At Natchaug and Norfolk the increase in sawtimber was real, each gained 16 trees per acre, but the number of poles declined. Nevertheless, loss of saplings was sufficiently great so that the propor- tion of poles increased or remained unchanged. In Catlin Wood the number of poles and sawtimber stems remained unchanged, but the proportions of both were reduced by the great increase in saplings. Minor species saplings increased in both Gay City and Catlin Wood, but the change was proportionally greater at Gay City. Over the average of all tracts and drainage classes we note slow movement of stems into pole and sawtimber classes (Table 12). During 1959-70, 3 red maple, 2 each of red oak, black birch and hemlock, and 1 white oak pole per acre became sawtimber (Table 13). Only sugar Table 13. Diameter class distribution (stems/acre), all tracts Small Saplings Large Saplings Poles Sawtimber 1959 1970 1959 1970 1959 1970 1959 1970 Sugar maple 7 8 30 25 10 11 1 1 Red maple 54 47 67 67 28 28 3 6 Red oak 10 4 15 6 13 10 9 11 Rlack & Scarlet oak 1 0 3 1 4 5 1 1 White oak 11 3 21 3 6 5 3 4 Yellow birch 23 19 28 24 13 15 1 1 Black birch 25 29 21 23 14 14 1 3 Beech 48 60 33 41 6 6 0 0 Hemlock 11 57 38 51 14 17 9 11 maple, yellow birch and hemlock poles increased. Sapling losses were greatest in red and white oak and were slight among maples and yellow birch. Saplings increased in black birch, beech and hemlock. In Gay City, white oak and black birch, each with 4 sawtimber trees per acre, comprised half the sawtimber in 1959. By 1970, 3 addi- tional black birch and 2 red maple became sawtimber. In 1970 poles were numerous among red and scarlet oak, yellow and black birch, red maple and white oak. During the preceding decade the number of poles increased only for yellow and black birch and scarlet oak. Losses of saplings during 1959-70 were great for red and white oak, yellow birch, pignut hickory and white ash. Only red maple increased its saplings. At Natchaug, in 1959, all sawtimber trees were oak. Red oak supplied 13 per acre, while scarlet and white oak each had 3. During 34 Connecticut Experiment Station Bulletin 718 1959-70 10 additional red oak, 4 white oak and 3 black birch grew to saw-timber. Red maple, white oak and black birch had many poles in 1970, but only red maple had increased in number during 1959-70. The number of red and white oak saplings declined sharply by 1970. Red maple decreased about 20 percent, but black birch saplings in- creased about 20 percent. At Norfolk red maple, red oak, black cherry and hemlock com- prised 30 of the 38 sawtimber trees per acre in 1959. During 1959-70 red maple and hemlock each added 5 while sugar maple and white ash each contributed 2 sawtimber stems per acre. In 1970, poles were numerous among sugar and red maple, yellow birch, beech, white ash, and hemlock. Only sugar maple and hemlock gained poles during 1959-70. Saplings increased only for beech and decreased among sugar maple, yellow birch, and hemlock. Catlin Wood had the greatest number of sawtimber trees per acre. In 1959 there were 29 hemlock, 18 red oak, 4 white oak and 4 white pine sawtimber trees per acre. In the decade that followed, red maple and hemlock each produced 2 additional sawtimber stems, but red oak lost 2. Poles were most numerous among red maple, red oak, yellow birch, and beech. During 1959-70 the number of poles increased only in yellow birch and hemlock. Only among beech, hemlock, and white pine did the saplings increase. Thus, we see that mortality mainly affected the saplings of each species. Apparently few of the larger trees died. Growth into pole and sawtimber classes was slow. Sugar maple, scarlet oak, yellow birch, and hemlock all increased their poles, while red maple, red oak, black birch, and hemlock increased sawtimber stems. Now we can better appreciate the distinction in describing the forest in terms of stem number or basal area. Red maple, although numerous, did not bulk large in basal area because most of its stems were saplings. Red oak, though few in number had a large basal area because nearly half its stems were poles or sawtimber. We go now to a closer examination of growth and loss among species. GROWTH We have witnessed a kaleidoscope ol change in the forest. Popu- lation revealed net change in numbers but nothing of size of individuals. Birth enumerated newcomers and implied they were small, while death indicated only that stems disappeared, bul not whether they were small or large. Basal area related net change of the forest's bulk but nothing ol its dynamics. Distribution ol diameter revealed that mostly small stems disappeared and indicated whether others grew to larger size or did not. We now analyze basal area change in order to learn its dynamics. To do this we separate three components ol change: accre- tion, growth on persistenl stems; ingrowth, additions by new stems; Drainage, Drought, Defoliation, and Death 35 and mortality, loss of those that died. If their sum is positive, growth of the stand has occurred. We already know that basal area increased on all sites of all tracts except on the moderately well drained soil in Gay City. Let us see the contribution of each component (Table 14). Over all tracts and sites Tabic 14. Basal area change (sq. -ft. /acre), major species Poorly Moderately Well Somewhat Drained Well Drained Drained Exc. Drained All Gay City Accretion 21.1 13.4 16.3 17.5 17.0 Ingrowth .4 .4 .8 .5 .5 Mortality -7.8 -14.6 -11.8 -4.4 -9.9 Net 13.7 -.8 5.3 13.6 7.6 Natchaug Accretion 14.3 19.6 17.8 Ingrowth 2.5 1.7 2.0 Mortality -8.1 -8.5 -8.4 Net 8.7 12.8 11.4 Norfolk Accretion 23.8 23.5 15.1 21.5 Ingrowth .5 .1 .3 .3 Mortality -5.7 -6.9 -7.7 -6.6 Net 18.6 16.7 7.7 15.2 Catlin Wood Accretion 33.4 20.2 29.7 25.8 Ingrowth 1.3 2.5 3.6 2.6 Mortality -1.9 -11.9 -1.5 -6.8 Net 32.8 10.8 31.8 21.6 All Accretion 23.2 19.7 20.4 17.5 20.7 Ingrowth 1.1 1.5 1.6 .5 1.3 Mortality -5.9 -10.2 -7.3 -4.4 -7.9 Net 18.4 11.0 14.7 13.6 14.1 nearly 21 square feet per acre accrued to basal area of persistent trees. Ingrowth of new trees added a meager 1.3 square feet while mortality withdrew nearly 8 from the basal area present in 1959. Thus, on the average, mortality nullified about a third of all growth. Accretion was greatest on the poorly drained soils and least on the somewhat excessively drained. However, expressed as a percent of persisting basal area (1959 basal area minus mortality), accretion 36 Connecticut Experiment Station Bulletin i IS was greatest, not least, on the somewhat excessively drained, 29 per- cent, and least on the well drained, 17 percent. Ingrowth was essen- tially constant; it varied from nearly 1 to less than 2 percent of per- sistent basal area. On the other hand, mortality varied more than in- growth. As a percent of the 1959 basal area it varied from 10 percent on moderately well drained sites to about 5 percent on the poorly drained. Net change, similarly expressed, was greatest on the some- what excessively drained soil, nearly 21 percent; less on the poorly drained, 16 percent; and least on the moderately and well drained sites, about 11 percent. Because ingrowth is nearly constant, net change varied only with the balance between accretion and mortality. Among the tracts, average accretion ranged from 17 square feet per acre on Gay City to nearly 26 in Catlin Wood (Table 14). As a percent of persistent basal area, however, accretion was greatest at Gay City, 27 percent, and least in Norfolk, 15 percent. Ingrowth was less than 1 percent of persistent basal area at Gay City and Norfolk, but more than 2 percent at Natchaug and Catlin Wood. Mortality was greatest at Gay City, nearly 14 percent of 1959 basal area, and least at Norfolk, less than 5 percent. Nevertheless, net change was nearly equal and least at Gay City and Norfolk, about 10 percent of 1959 basal area, greater at Natchaug, 14 percent, and greatest at Catlin Wood, nearly 17 percent. Thus, the proportional net change among tracts mainly depended on the balance of accretion and mortality, something already seen in the comparison of growth among drainage classes. At Gay City accretion was less and mortality greater on the moderately and well drained sites than on the others. On the mod- erately well drained soil, mortality of red and white oak and yellow birch exceeded accretion and ingrowth. On the well drained soil, these species plus black oak and pignut hickory all had great mortality. On the poorly drained, accretion was great and mortality slight for red maple, white oak, yellow birch and white ash. On the somewhat ex- cessively drained soil red maple, red and scarlet oak and black birch all displayed large net increases. At Natchaug, accretion was greater on the moderately well drained than on the poorly drained soil. Although ingrowth was less and mortality greater, net change on the moderatelj well drained was nearly 50 percent greater than on the poorly drained. On the poorly drained soil, mortality of black birch exceeded accretion and ingrowth three-fold. On the oilier hand, net increase oj vril maple was great. On the moderatel) well drained site, red oak had much accretion and no mortality whereas mortalit) <>l white oak exceeded growth more than two-fold. In Norfolk, accretion on the well drained site was only two-thirds as greai as on the poorl) and moderately well drained soils. As drain- age improved, mortalitj Increased with the resull thai nel increase on Drainage, Drought, Defoliation, and Death 37 the well drained soil was less than half that on poorly and moderately well drained soils. On the poorly drained site, hemlock, yellow birch, and white ash all increased, but red maple declined. On the mod- erately well drained soil, red maple, red oak, beech, and hemlock gained in basal area, but mortality of black cherry exceeded growth about 50-fold. On the well drained soil, sugar maple and yellow birch declined, whereas red oak, beech, and black cherry provided nearly all the gain in basal area. At Catlin Wood net increase on poorly and well drained soils was three times that on moderately well drained soil. Not only was accretion a third less on the moderately well drained soil, but mor- tality was about six times greater than on the other sites. On the poorly drained soil, hemlock, red maple, yellow birch, and white pine provided nearly all of the gain in basal area. On the well drained soil, hemlock, red oak, red maple, beech, and yellow birch grew much and died little. But on the moderately well drained soil the greater mortality of red oak cancelled more than a third of the gain contributed by red maple, black birch, beech, and hemlock. The average changes in components of basal area of selected species are shown in Table 15. Accretion and mortality varied among species, but ingrowth was slight for all. Sugar maple was not found on the driest site and it grew slowly elsewhere; accretion was about 9 percent of persisting basal area. Although mortality was slight compared to other species, it equaled about 60 percent of the growth of sugar maple for the decade. Accre- tion was greatest on the moderately well drained soils. Red maple, on the other hand, grew more rapidly on all sites. Average accretion was 22 percent of persisting basal area and mortality, 4 percent of 1959 basal area. Both accretion and mortality were proportionally greatest on the somewhat excessively drained soil. Yellow birch generally grew more than sugar maple but less than red maple. Like sugar maple, it was not found on the driest site. On the average, mortality equaled half the growth. Proportionally, accre- tion was greatest on the moderately well drained sites, 19 percent, and least on the well drained, 4 percent. Mortality was least on the poorly drained and greatest on the well drained soils. Black birch, on the other hand, grew as well as red maple, and growth was nearly three times mortality. Although accretion was proportionally greatest on the poorly drained sites, the great mortality there caused basal area to decline. On other sites accretion became proportionally greater as drainage improved. Because mortality varied, net increase was greatest on well drained soils. Although black and yellow birch had greatest net increases on well drained soils, yellow birch grew well on the moister and black birch grew well on the drier soils. Red and white oak occurred on all sites. Average mortality of red oak equaled about two-thirds of accretion while that of white ex- 38 COXXECTICUT Experiment Statiox BULLETIX 718 Table 15. Basal area change (sq. ft. /acre), all tracts Poorly Moderatelv Well S. Excess. Species Component Drained Well Drained Drained Drained All Sugar maple Accretion .01 .64 1.05 .52 Ingrowth .0 .0 .03 .01 Mortality .0 -.20 -1.00 -.32 Net .01 .44 .08 .21 Red maple Accretion 5.9 3.9 .88 5.5 3.9 Ingrowth .5 .2 .07 .3 .3 Mortality -1.7 — .5 -.07 -1.3 -.8 Net 4.7 3.6 .88 4.5 3.4 Yellow birch Accretion 2.19 1.13 .03 1.10 Ingrowth .16 .05 .64 .22 Mortality -.34 -1.17 -.33 -.67 Net 2.01 .01 .34 .65 Black birch Accretion .42 1.72 3.5 2.15 1.81 Ingrowth .02 ,38 .0 .10 .17 Mortality -1.38 -.67 — .2 -.72 -.76 Net -.94 1.43 3.3 1.53 1.22 Red oak Accretion .05 5.2 5.3 4.4 3.7 Ingrowth .0 .0 .2 .0 < .1 Mortality -.34 -3.7 -2.5 -.5 -2.3 Net -.28 1.5 3.0 3.9 1.5 White oak Accretion 1.58 1.19 .78 .0 1.13 Ingrowth .0 .0 .0 .0 .0 Mortality -.14 -2.52 -.78 -.20 -1.30 Net 1.44 -1.33 .0 -.20 -.16 Beech Accretion .07 1.38 2.12 1.10 Ingrowth .05 .14 .16 .11 Mortality .0 -.19 -.07 -.10 Net .12 1.33 2.22 1.12 1 [emlock Accretion 10.6 3.5 4.6 5.5 Ingrowth .3 .6 .5 .5 Mortality — .3 .0 .0 -.1 Net 10.6 4.1 5.1 5.9 White ash Accretion 1.46 .33 .98 .78 Ingrowth .0 .0 .0 .0 Mortality -.62 - .06 -.81 -.39 \,i .84 .28 .17 .39 All major \< < retion 23.2 19.7 20,-) 17.1 20.7 Ingrowth 1.1 1.5 1.0 .5 1.3 Mortalit) -5.8 10.2 -7.3 -4.4 -7.9 Mel L8.5 1 1.0 1 IN 13.5 14.1 All minoi \> . ii lion .16 .30 .20 .06 .25 Ingrowth .43 .34 .25 .IS .34 Mortalit) L.06 -.51 .50 -.34 -.65 Nel -.47 .13 .05 .10 - .06 Drainage, Drought, Defoliation, and Death 39 ceeded accretion. On the poorly drained soils, mortality of red oak exceeded growth seven-fold. Although accretion was great on mod- erately and well drained soils, mortality, too, was large. Hence, net increase of red oak was greatest on the driest site where mortality was least. Conversely, white oak increased its basal area only on the poorly drained sites; on all other sites mortality equaled or exceeded accretion. Beech and hemlock both grew much and died little. Neither oc- curred on the driest site and both made maximum gain on the mod- erately well drained soils. Beech had the greatest proportional rate of net increase, 37 percent of 1959 basal area. Hemlock was second with 24 percent increase. Mortality of white ash equaled half its accretion. Despite great mortality, net increase was greatest on the poorly drained soils. Al- though considerable ash was present on well drained soils, mortality was more than 80 percent of accretion. In summary, we note that red maple grew well on all sites. White oak, white ash, and yellow birch increased most on the poorly drained soils, while red oak increased most on the driest. Hemlock, the rapidly growing beech, and the slow growing sugar maple grew best on the moderately well drained sites. Although all sites remained nearly equally diverse with respect to numbers, change in basal area varied with species and drainage. CANOPY COMPOSITION The indistinct outline of the forest seen from afar is its main canopy. The physiognomy of the forest and often its future composi- tion is dictated by the species whose dominant and co-dominant crowns comprise the canopy. Closer inspection reveals intermediate and over- topped crowns, often in a middle or lower story beneath the main canopy. These species, too, are important because they may affect future composition should some catastrophe befall individuals in the main canopy. What determines participation in the main canopy? In the new forest this is decided by those first appearing and others which grow most rapidly in height. Further, only in the young forest can shrubs and short-statured trees participate in the canopy. However, in the more mature forest other factors predominate. If a species is numerous, likely some of its stems will be in the canopy; if its basal area is great, surely large trees will be present in the canopy. Tolerance to shade is also important unless the main canopy is broken or open. If a species cannot persist in the shade of others, then it must participate in the canopy if it is to exist. We may consider canopy composition from two aspects. First, what proportion of each species participates in the canopy? If only a small proportion of stems participates in the canopy, then there must 40 Connecticut Experiment Station Bulletin 718 ■a 52 >H i—i i-h i— i u ^ 5 H (M h o N (M Tf (M ffiWOC^t r-.ccioM(MXNNC- iffiOlfiH ■So W CD © ID © CC O 02 (OCDOtCC x o -* g WCb — < >-< »ObC X CO b- S«S WOOWO CD O CC Ol Ol O ■* C 3 O Lfi •2 £ £ lOOt- "-i lO b- © CO CO CC CO « o5 o o G CT '""' lO ^HIO ' OOWHH 10 ^h 02 O5TfKc0CCCO>X jrccccc ot>W"*ooOr-4oa 051010c cocooooooooh« n ^ r- 1 ^ J5 00 co cq co looioot-oococo <; co id b- b- ©©©©©©©cm-* coco i— 1 cdcohh m WHoob in t}< o!CC(dc £ PC *-* < «3 CO III < O -^In P lO CM 02 ©©-*■<# CM 0©©"tfl> W10lOC32 ©©COCCCCCCCCOTf 4? 5 f; -1 C-l X OCOHH OC i-h r, Tf CD 32 C Q IP (O H O C © b- V O ~ f£ X © C2 OCMCOCOOOOOOCO Z m CM b- ©l010C0Gb-©©CMb- W "5 -r !G HlO M ,-h CMC i-h .-H H CM ID CO lO CM lO rf O CCIO p-. ce; w Ph i P O ^ C CO 02 1— ( O CO C^h 10 Ob-© ^COOCCO ,9 K CO CO CM -—I CO lO CM CM t- Obffl ffi 10 rt b 0 0 © 00 © 0 10 c -h IO b C (E O O CM PIClH CC C i-H CC 02 CD lO 02 3 lO CC £• Drainage, Drought, Defoliation, and Death 41 be many smaller stems tolerant of shade in the understory. Increased participation in the canopy results from death of small stems in the understory or growth of smaller stems into the canopy. In 1959, 14 percent of all major species stems participated in the canopy (Table 16). Slightly more, 16 percent, participated on the poorly and some- what excessively drained soils and fewer, 13 percent, on the moderately and well drained. By 1970, average participation increased to 19 per- cent and ranged from 17 percent on the moderately well drained to 25 percent on the poorly drained soils. Increases occurred on all sites. These apparent increases resulted mostly from death of small trees and from a few growing to larger size as seen in distribution of diameter (Table 13). The largest increase in canopy participation occurred on the poorly drained soils. For example, in 1959, 41 percent of red oak stems participated in the canopy; by 1970, 63 percent participated (Table 16). However, we already know that its saplings declined greatly during 1959-70 (Table 13). Proportionally more stems participated in the canopy because the small stems could not persist in the shade. On the other hand, the proportions of red and sugar maples in the canopy changed little, because few small trees became large and because most of the saplings persisted. In 1959, few minor species participated in the canopy; only 2 per- cent on poorly drained and 1 on moderately well drained soils. They were bluebeech, witchhazel, and winterberry. By 1970, no minor species remained in the canopy. Apparently growth of the stands raised the canopy beyond their reach. We did not measure the area of each crown, but we know the basal area of each stem and its crown class. We can assume that crown or leaf area of a tree is proportional to its basal area. Thus, we can estimate participation in the canopy in a different way. The proportion of major species participating in the canopy was much greater for basal area than for number, 61 percent in 1959 and 77 in 1970 (Table 16, lower half). In 1959, the proportion ranged from 57 percent on the moderately well drained to 65 on the some- what excessively drained soil. By 1970 participation ranged from 74 percent on the moderately well and somewhat excessively drained sites to 82 percent on the well drained. Thus, in 1970 we estimate that nearly a fifth of the stems supported about three-fourths of foliage. The second aspect of canopy composition is the proportion of the canopy occupied by each species. This reveals which species control the forest. In 1959, oaks and birches dominated canopy composition with their numbers (Table 17). During 1959-70 maple remained con- stant, oaks declined while birches, beech, and hemlock increased. On the poorly drained sites only hemlock increased its participation, all others declined. On the moderately and well drained soils white oaks, 42 Connecticut Experiment Station Bulletin 718 Cfc Hr- ^H ,-1 1-1 C lH Ol CM © 55 2 ,_l •" u <; g " el oi — i 05 •—■ CM el o iH CM © CO 2 Q 2 g .£ g5 m o oi in c v; C HO V2 OH- N IC C C CM CM CO iH CI 00 00 t> O lO CI CM CO V! v: w ? P M IM X C TfolOTfWCMTfoOO co n oo co cocooorocoro^o i— I CM ■— I O NMO-*-*Ortq» - ^ "5 k S c-i n ih ct> £2 ^■*1>C0 ^XWXHXHCTfOlC ^ ?— I CO I — C^ < CO CO 05 CCBCOCOOCMTfC'^MC g HCO ^H C U ■iPOHO 10 CM CM C 00 CM O r-i C O CD C CM CO . . O CM C (M H O !C IOChO r ir — 7. — C ^ Pu, 1- -t el C -t el -t< >— i 10 cO^NOb <0 V- -^ -i t- flj O O jl Jj .9 — ' — _/ 5 O f> BQ -5 2,.° o< ^ "2 M O — U 1' ? "7 5 3 x tf S 2 x M &_y « C O 5 '- J? — n= -* »2 '« _ "^ ^ jrf J^ .£2 < _^: -r- .i _^c z! -— v" — - c/sPfirtPQc/J^^PQPPi^PQi^ffiOE-1 Drainage, Drought, Defoliation, and Death 43 yellow birch, beech, and hemlock were among those with increasing participation in the canopy. On the driest site only black birch in- creased. Using the assumed relation between basal and foliage area, we estimate that red maple, red oak, and hemlock contributed about two- thirds of the foliage in the canopy (Table 17, lower half). However, the proportions varied considerably among tracts. Gay City and Natchaug had no conifers. In 1970 at Gay City, birch comprised 38 percent, oak 30, and maple 17 percent of the canopy. At Natchaug, oak constituted 72 percent, birch 13, and maple 8 percent of the canopy. Hemlock was abundant at Norfolk and Catlin Wood. At Nor- folk it comprised 26 percent of the canopy and at Catlin Wood, 42 percent. Maples provided 34 percent, oaks, 15 percent and birches 7 percent in Norfolk while at Catlin Wood their proportions were 10, 34, and 5 percent, respectively, in 1970. You will recall the description given each tract during the discus- sion of basal area. Description according to canopy composition yields essentially the same result. Gay City remains a birch-oak-maple forest and Natchaug, oak-birch. Norfolk continues as a hemlock-maple forest and, although oak was a small proportion of total basal area, it looms larger in canopy composition. The oaks present were large and in the canopy. Although oaks in the canopy decreased from 45 to 34 percent during 1959-70, Catlin Wood remains a hemlock-oak forest. We have viewed the changing forest from many vantage points, and we now know what has occurred. But what of the future? We shall use these observed changes to fortell the future in Predicting Change. PREDICTING CHANGE Our observations at the beginning and end of a decade enable us to characterize both the present population of the forest and past changes through birth, growth, and death of individuals. However, we would also like to know what the forest will become, barring catastrophe. Transition probabilities are a useful tool for predicting change in unmanaged forests (Waggoner and Stephens 1970, Stephens and Waggoner 1970). We have two sets of observations from which to determine the transitions, and we do so in order to evaluate their reasonableness and to compare them with transitions observed in the Meshomasic tracts. But first, let us define transition probability. If an object can exist in any one of the several states, transition occurs whenever the object changes state. If change is frequent, then it is probable. By studying many changes among states, we can express each possible transition as a probability, hence, transition probability. In this study our objects are small plots of land and their state is determined by the kind of vegetation growing upon them. From our 44 Connecticut Experiment Station Bulletin 718 observations of many plots at the beginning and end of a decade we determine their persistence in the initial state or their transition to another. A matrix of the probabilities of all possible transitions pro- vides a useful summary of change. The transects sampled were divided into plots of approximately one-eightieth of an acre. The initial and subsequent states of each plot were determined from the 1959 and 1970 observations. Because Norfolk and Catlin Wood contained many conifers their transitions were determined separately from Gay City and Natchaug. Because there were few plots, all drainage classes were considered together. Many states could be denned but we will consider only six: maples, oaks, birches, other major species, minor species, and conifers. The last species group or state occurred only at Norfolk and Catlin Wood and consisted mainly of hemlock with some white pine. The assignment of state was determined by the species group with the greatest number of stems per plot. The transitions obtained are in Table 18. We could have defined states based on tolerance to shade Table 18. Transition probabilities (percent) among species groups during 1959-70 accord- ing to number of stems on one-eightieth-acre plots 60 plots from Gay City and Natchaug ; (no conifers) ( >bserved 1959 1970 1 Maple Oak Birch Other* Minor Maple 95 14 20 34 11 Oak 0 14 0 0 0 Birch 5 0 70 33 1 1 Other 0 0 0 0 0 Minor 0 72 10 33 78 68 plots from V orfolk ant / Catl in Wood < many conifers) Observed L959 L970 i Maple Oak' Hi rch Other \l [nor ( lonifer Maple Hi 0 0 o 0 0 Oak 0 0 20 o o 0 Birch it 0 SO 0 0 0 Other 33 0 0 88 1 1 I) Minor 0 ,, (1 (i 78 5 < Ionizer ^7 87 0 6 1 1 95 Based on three plots Drainage, Drought, Defoliation, and Death 45 and basal area of stems, but irregular distributions of plots among states in 1959 gave transitions which seemed unreliable. The diagonal elements from upper left to lower right of each matrix reveal the persistence in initial states. The off-diagonal elements in each column indicate transitions to other states. Where conifers were absent at Gay City and Natchaug, maple, birch, and minor species persisted. Oak showed little persistence due to great mortality and was succeeded largely by minor species. Plots initially dominated by other major species went equally to maple, birch, and minor species. Although this likely reflects the relative increases of maple and birch, we must accept these transitions with caution because only three plots were dominated by other major species in 1959. Study of the matrix suggests that if these transitions continue steadily with time there will be many plots dominated by maple, birch, and minor species, few by oak, and none by other major species. Where conifers were present at Norfolk and Catlin Wood we see moderate persistence of maple and great persistence of birch, other major species, minor species, and conifers. Oak showed no persistence, but again, we accept this cautiously because only three plots were dominated by oak in 1959. The marked persistence of conifers, com- bined with transitions of nearly all groups directly to conifer, suggests that conifer will dominate many plots in the future. Further, except for the transition of birch to oak there are no other transitions into maple, oak, or birch. Thus, we anticipate a future forest with many plots dominated by conifer, other major species, and minor species, but eventually none by maple, birch, or oak. In both matrices of Table 18 the persistence of maple, birch and minor species and the decline of oak resemble the transition prob- abilities obtained in the Meshomasic tracts during a similar decade, 1957-67 (Stephens and Waggoner 1970). Thus, similar transition prob- abilities appear to exist for several stands over a large area. Transition probabilities have useful properties (Ashby 1966). If they are unvarying with time and if they depend only on the present state, that is, if they are independent of antecedent, then they describe a stationary Markov chain (Feller 1950). The transitions for one ob- servation period may be extrapolated to anticipate changes over sev- eral and the steady state, or dynamic equilibrium may be calculated. Steady state occurs when the proportion of objects in each state ceases to change; gains to a state are balanced by losses to other states. (The interested reader may wish to refer to a more detailed account by Feller (1950) or Kemeny and Snell (I960).) Unfortunately, we had only two sets of observations in time so we cannot be certain of the transitions' constancy and there were too few plots to ascertain independence of antecedent. Since the observed transitions in Table IS are similar to others from the Meshomasic 46 Connecticut Experiment Station Bulletin 718 tracts, which appeared Markovian (Stephens and Waggoner 1970). we are encouraged to make the same assumption for the present prob- abilities. The calculated steady states are in Table 19 . Table 19. Steady states (percent of total) anticipated from 1959-70 transitions among species groups according to the number of stems on one-eightieth-acre plots 60 plots from Gay City and Natchaug (no conifers) Maple Oak Birch Other Minor 79 1 14 0 6 68 plots from Norfolk and Catlin Wood (many conifers) Maple Oak Birch Other Minor Conifer 0 0 0 IS 20 62 As we anticipated from study of the matrix in Table 18, at the calculated steady state most plots in Gay City and Natchaug will be dominated by maple; on some, birch, and minor species will pre- dominate. Oaks will dominate very few plots with their numbers and other major species will dominate none. At Norfolk and Catlin Wood three-fifths of the plots will be dominated by conifers and a fifth each by other major species and minor species. The transitions anticipate future forests with little oak. Previous work indicates that the decline of oak has continued for at least 40 years but may have accelerated recently (Stephens and Waggoner 1970). Therefore, the outcome of the transitions may be closely related to the events examined in the next section. DROUGHT, DEFOLIATION, AND DEATH Drought and defoliation varied among the tracts during 1959-70. In previous sections we have related change to drainage of the site and age of the tract, [n this section we will present the effects of drought and defoliation and give the importance of each. In describing the forests we noted that all tracts received 8 to L5 percenl less average annual precipitation dining L959-69 than in the preceeding 6 to 10 years. Despite the reduction of precipitation, how- ever, we can characterize Norfolk as moist. Catlin Wood as moderate- ly moist, and C;i\ Cit) and Natchaug as moderate!) drj (luring 1959- 69. Further, we noted that Catlin Wood and a portion of (.;i\ City were defoliated once, while the remainder ol Gay ('itv suffered a sec- ond defoliation. No defoliation was recorded For Natchaug or Norfolk. \n accounl ol the effect ol defoliation on these new tracts as well as on the Meshomasic series was published separately (Stephens 1071 | because "I its great importance in deciding upon insect control mea- sures. The effeel ol defoliation is also examined hero For the benefit ol the readers ol the present Bullet in. Drainage, Drought, Defoliation, and Death 47 During our examination of death we found little relation of death to drainage class. Rather, it was more clearly related to population (Figure 3). What are the effects of drought and defoliation? The trend line of death on population removes the effect of population; there is no difference between moist Norfolk (o) and dry Natchaug (x). Thus, drought apparently had little effect on death in undefoliated tracts. Nor does Catlin Wood (A), defoliated in 1956, differ from unde- foliated Natchaug and Norfolk. Although newly dead oaks were re- corded in Catlin Wood in 1959, either any increased death due to de- foliation had already occurred or could not be detected during 1959-70. Thus, a single prior defoliation apparently did not produce a lasting effect on death. Among the defoliated and draughted sites of Gay City (o) we do discern a difference. Death in the once defoliated dry site (4) and the twice defoliated poorly drained site ( 1 ) was no different than on undefoliated sites in other tracts (Fig. 3). On the twice defoliated moderately (2) and well drained sites (3), however, death was clearly greater. These sites, normally optimum for tree growth, had the greatest loss. This is similar to observations made in western Con- necticut (Stephens 1963). Thus, abundant soil moisture offset the effect of repeated defoliation. In Catlin Wood and undefoliated Natchaug and Norfolk, average annual loss of major species ranged from 0.5 to 1.6 percent of the 1959 population. On the moderately well drained site, present in all tracts, average annual loss was more uniform, ranging from 1.2 to 1.6 percent. On the once defoliated dry site of Gay City death was 1.5 percent annually, but it rose to 2.3 percent on the twice defoliated moderately and well drained sites. Thus, repeated defoliation nearly doubled the slight average annual death. During 1957-67, on the Meshomasic tracts which endured both drought and repeated defoliation average mortality varied from 1.6 percent of population on moist sites to 2.3 on the dry (Stephens and Waggoner 1970). The results of both studies are re- markably similar. Examination of species groups is more revealing. During 1959- 70 death of maple stems averaged 15 percent and ranged from 14 to 17 percent on individual tracts. Loss of birch averaged slightly more, nearly 19 percent, and ranged from 17 to 19 percent. Death of oak was considerably greater: death increased from 25 percent at cool, moist Norfolk to 43 percent at Catlin Wood, 47 percent at Natchaug and 55 percent at warm, dry Gay City. The great loss of this species group was concealed in Figure 3 by averaging it with the smaller losses of many other groups. In comparison, death during 1957-67 in the Meshomasic tracts averaged 18 percent for maple, 20 percent for birch and 46 percent for oak. On the once-defoliated dry site in Gay City, death was only 9 4S Connecticut Experiment Station Bulletin 718 percent for oak, 12 percent for birch, but 20 percent for maple. In contrast, on Gay City's twice-defoliated moister sites death claimed 72 percent of oak, 21 percent of birch, and 9 percent of maple during 11 years. If we consider the climate of Gay City and Natchaug similar, then repeated defoliation increased oak loss from less than 5 percent annually to more than 7 percent; about a 50 percent increase. On the other hand, loss of birch differed little and death of maple was actually greater at Natchaug than at Gay City. Thus, loss of oak exceeded the average for all major species in all tracts. It increased with severity of drought and further increased with repeated defoliation. In terms of 1959 basal area, mortality of oak during 1959-70 was 8 percent at Norfolk, 10 percent at Natchaug, 12 percent at Catlin Wood, and 24 percent at Gay City. Again, we see little difference be- tween cool, moist Norfolk and warm, dry Natchaug. Nor was Catlin Wood greatly different. At Gay City mortality was only 2 percent of 1959 basal area on the dry site, 7 percent on the poorly drained, but 37 percent on the well drained, and 67 percent on the moderately well drained. During the 11 years, the average annual losses were .2, .6, 3, and nearly 7 percent, dramatically greater on the twice-defoliated sites. However, average annual losses may be misleading if the period of observation is long. In this report and in the report on the Meshomasic tracts, defoliation occurred near the middle of the observation period. If great losses were sustained during the year or two immediately fol- lowing defoliation, subsequent mortality might be reduced below nor- mal because of the thinning of the forest. By the end of the period, however, the average might be little different from normal. For ex- ample, if a species normally loses 20 percent of its stems during a decade, or 2 percent annually, but suddenly at the midpoint loses 5 percent annually for two years and 1 percent thereafter, the loss for the decade is 23 percent or 2.3 percent annually. Average annual death is little changed despite greater losses immediately after defoliation. We know that oak mortality increases after defoliation. However, onl) annual observation will determine whether mortality increases sharply and then subsides or whether it varies less dramatically over a longer lime. Oak is a preferred host lor man)- defoliators. Thus, even in years without major defoliation oaks may be attacked. For example, during late spring, 1970. when the tracts were re-examined, the spring canker- worm (Paleacrita oernata) and other defoliators were active in Gaj City and Catlin Wood. Defoliation ol the main canopy was light, less than 25 percent, hut man) oaks were badly defoliated. II such attacks occur repeatedly, there is little wonder that oak declines. In Predicting Change we anticipated that (he oak population will dwindle. Hopefully, as it docs, losses from defoliation will also do crease as insects are deprived ol a laxored host. ()nl\ through con- tinued observation and comparison will we know whether defoliators arc speeding the observed decline ol oak. Drainage, Drought, Defoliation, and Death 49 Literature Cited Anonymous. 1951. Soil survey manual. U.S. Dept. Agr., Agr. Handbook 18. 503 p. Ashby, W. R. 1956. An introduction to cybernetics. Science Editions. Tobn Wiley & Sons, Inc., New York, N.Y. 295 p. Collins, S. 1962. Three decades of change in an unmanaged Connecticut woodland. The Conn. Agr. Expt. Sta., New Haven. Bull. 653. 32 p. Feller, W. 1950. An introduction to probability theory and its applications. Vol. 1. John Wiley & Sons, Inc., New York, N.Y. 419 p. Fernald, M. L. 1950. Gray's manual of botany. Eighth ed. American Book Company, New York, N.Y. 1632 p. Kelsey, H. P. and W. A. Dayton, 1942. Standardized plant names, 2nd ed. J. Horace McFarland Co., Harrisburg, Pa. 677 p. Kemeny, J. G. and J. L. Snell, 1960. Finite markov chains. D. VanNostrand Co., Inc., Princeton, NJ. 210 p. Little, E. L., Jr. 1953. Check list of native and naturalized trees of the United States (including Alaska). U.S. Dept. Agr., Agr. Handbook 41. 472 p. Olson, A. R. 1965. Natural changes in some Connecticut woodlands during 30 years. The Conn. Agr. Expt. Sta., New Haven. Bulletin 669. 52 p. Pielou, E. C. 1969. An introduction to mathematical ecology. Wiley Interscience. John Wiley & Sons, New York, N.Y. 286 p. Smith, D. M. 1956. Catlin Wood. In Six points of especial botanical interest in Con- necticut. Connecticut Arboretum, Connecticut College, New London. Bulletin No. 9. p. 19-24. Society of American Foresters, Committee of Forest Terminology. 1950. Forest Ter- minology. Society of American Foresters, Washington, D.C. 93 p. Stephens, G. R. 1963. Tree mortality resulting from defoliation in 1962. The Conn. Agr. Exp. Sta., New Haven. Dept. of Ent. Rept. of Progress No. 15. 2 p. Stephens, G. R. 1971. The relation of insect defoliation to mortality in Connecticut forests. The Conn. Agr. Expt. Sta., New Haven. Bull. No. 723. 16 p. Stephens, G. R. and P. E. Waggoner. 1970. The forests anticipated from 40 years of natural transitions in mixed hardwoods. The Conn. Agr. ExDt. Sta., New Haven. Bull. No. 707. 58 p. Waggoner, P. E. and G. R. Stephens. 1970. Transition probabilities for a forest. Nature 225:1160-1161. 50 Connecticut Experiment Station Bulletin 718 Common and Scientific Names of Plants Mentioned in This Bulletin (Kelsey and Dayton 1942, Fernald 1950. Little 1953) Ash, white— Fraxinus americana black— Fruxinus nigra Aspen, bigtooth— Populus grandidentata Basswood— Tilia americana Beech— Fagus grandifolia Birch, black1— Betula lenta yellow— Betula alleghaniensis gray— Betula populifolia Bluebeech1— Carpinus caroliniana Blueberry, highbush—Vaccinium corymbosum Cherry, black— Primus serotina Chestnut, American— Castanea dentata Dogwood, flowering— Cornus florida Elm, American— Ulmus americana I lemlock— Tsuga canadensis Hickory, shagbark— Carya ovata mockernut— Carija tomentosa pignut— Carya glabra Hophornbeam— Ostrya virginana Locust, black— Robinia pseudoacacia Maple, sugar— Acer saccharum red— Acer rubrum Oak, white— Quercus alba red— Quercus rubra scarlet— Quercus cuccinea black— Quercus velutina P< ppcridge— Nyssa sylvatica Pine, white— Pinus strobus R< -I' edar1 Juniperus virginiana Sassafras— Sassafras albidum Shadbush1— Amelanchier arborea Spi< cliiish— Lindera l>cnzoin Viburnum, arrow wood — Viburnum- den I at inn Witchhobbl* — Virburnum alnifolium Withered— Viburnum cassinoides Witchhazel Hamamelis virginiana Winterberry common Ilex vertieillata Local name differing from Fernald (1950), Little (1953) or Standardized Planl \. is (Kelsey and Dayton L942). 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