A DENDROCHRONOLOGICAL. Appmm' f, f: f {-527 ‘1 0F CLIMATIC, EDAPH‘IC‘, AND . 1 _ _ V FLORISTIC PATTERNS IN __ -a NORTHWESTERN-ATNDIANAV i; ‘ Thesis for the Degree of Ph. D. MICHIGAN STATE UNWERSITY .FRANK LANE CHARTON 1'9 7‘2 LI BRA " V Michigan Suite University Fwy-P- 9—..— \|\\|\\“\|\\\\||\\\|\\\\\|\\\\|\\\l\i\l\ “NW : ,fitblk This is to certify that the thesis entitled \A DENDROCHRONOLOGICAL APPRAISAL OF CLIMATIC. EDAPHIC, AND FLORISTIC PATTERNS IN NORTHWESTERN INDIANA presented by Frank Lane Charton has been accepted towards fulfillment of the requirements for Ph-D- degree infiengnaphy Date July 6, 1972 0-7839 alumna m} HUAB & SONS' TB"C'K B'NDERY WC L BRARY Immuams mm ABSTRACT A DENDROCHRONOLOGICAL APPRAISAL OF CLDflATIC, EDAPHIC, AND FLORISTIC PATTERNS IN NORTHWESTERN INDIANA BY Frank Lane Charton Northwestern Indiana is a tension zone between differ- ent phytogeographical regions. The actual penetration of meSOphytic species such as Fagus grandifolia (beech) and Acer saccharum (sugar maple) to the southwest, or of more xerophytic types such as Quercus (oak) and gagya (hickory) species to the northeast, is largely determined by local interactions of variables such as soil, topography, site history, and possibly local climate. The purposes of this study were to assess the relative influences of soils and climate in determining the distributions of mes0phytic and xerophytic forest types in northwestern Indiana and to search for tree-ring evidence of any locally important climatic patterns, particularly in the vicinity of La Porte where an anomalously high precipitation pattern was recorded from 1930—63. An additional aim was to compare the relative sensitivities of Quercus velutina (black oak) and Quercus alba (white oak) to environmental stress. It was hypothesized Frank Lane Charton that patterns of tree—ring variation in northwestern Indiana would indicate a general westward gradient of increasing moisture stress, and that local departures from the regional tree-ring chronology would be present in wood samples from the La Porte area. Tree cores and soil samples were collected from thirty— four stands of white oak and six stands of black oak near selected weather stations in Lake, Porter, and La Porte Counties, Indiana. Analysis of variance and inter-correla— tion techniques applied to 81-year tree-ring chronologies provided statistical parameters which permitted an evaluation of tree-response to environmental variation. The regression of these parameters against soil texture suggested a positive relationship between moisture stress and the amount of very fine clay in the subsoil. Frequently, tree sensitivities were about 15-20% higher on finer—textured soils than on coarse soils. Regression analyses of tree-ring indices and selected climatic data indicated significant relationships between spring and early summer weather to total annual ring-width. While dendrochronological investigations did not suggest a direct climatic control of the forest ecotone, the restric- tion of mesic species such as Fagus grandifolia (beech) to sites of moderated moisture stress indicates that climate may be marginal to the survival of mesic species in the Frank Lane Charton area. It was concluded that the immediate control of the forest transition in northwestern Indiana is very likely soil texture. Thus, the hypothesis of increasing moisture stress westward through northwestern Indiana appears to have been supported, but the stress is evidently related to a westward transition to finer—textured soils rather than to a general climatic gradient. Comparisons of white oak and black oak tree-ring para— meters yielded higher sensitivities to environmental stress in black oak. In future dendrochronological research, black oak will probably be a more useful species than white oak when available. Evidence for an anomalous precipitation regime in tree- cores obtained from the La Porte vicinity was inconclusive. Correlations between tree-ring indices and selected climatic data did not reveal the post-1930 decreases which would be expected with unusually large increases of moisture, and decreases of tree sensitivity after 1930 were no greater than would be attributed to aging. It is suggested that any deviations in the tree-ring record at La Porte resulting from local climatic variations probably would have been obscured by either declining sensitivity accompanying forest maturation and/or by the already low sensitivity characteristic of the oaks growing on the coarse soils near La Porte. A DENDROCHRONOLOGICAL APPRAISAL OF CLIMATIC, EDAPHIC. AND FLORISTIC PATTERNS IN NORTHWESTERN INDIANA BY Frank Lane Charton A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Geography 1972 U U ,4. 2 To Sylvia Who asks so very little but gives so very much. ii ACKNOWLEDGEMENTS The author wishes to thank the many individuals who assisted in the completion of this research project. Special appreciation is directed to Dr. J. R. Harman for his guidance during all stages of the dissertation. His encouragement and advice have been memorable part of my graduate experience. I am also indebted to Professors G. K. Higgs and H. A. Winters of the Department of Geography and E. P. Whiteside of the Department of Crop and Soil Science for their helpful suggestions. Among the people who aided in various phases of this project are: Dr. D. P. White of the Department of Forestry, Michigan State University; Dr. R. I. Wittick of the Depart— ment of Geography, Michigan State University; Dr. H. C. Fritts and.Ms. L. Drew of the Laboratory of Tree-Ring Research, University of Arizona, Tucson; Mr. N. D. Strommen of NOAA--National Weather service, East Lansing, Michigan; and Ms. D. Pritchard and.Mr. L. Seeger of the United States Soil Conservation Service, Crown Point, Indiana. Final drafting of the maps and diagrams was done by Mr. S. Hollander. For financial aid given throughout my graduate program, I am grateful to the Department of Geography, Michigan State iii University. Financial assistance provided during the com- pletion of this project by the National Science Foundation and by the Computer Institute for Social Science Research at Michigan State University is also acknowledged. Finally, the author realizes that without the under— standing and help of both his family and his wife's mother, the realization of this study would have been far more difficult. iv TABLE OF CONTENTS CHAPTER LIST OF TABLES. . . . . . . . . . . . . . LIST OF FIGURES . . . . . . . . . . . . . I. INTRODUCTION. ... . . . . . . . . . . . . Nature of the Problem. . . . . . . . . Hypotheses and Research Aims . . . . . II. THE PHYSICAL SETTING. . . . . . . . . . . III. IV. Study Area . . . . . . . . . . . . . . Review of the Phytogeographical Litera ture. . . . . . . . . . . . . . . . METHODS . . . . . . . . . . . . . . . . . Physiological Foundations of Dendro- chronologyC . . . . . . . . . . . . Procedures in Tree-Ring Analysis . . . Site Selection. . . . . . . . . . . Specimen Collection . . . . . . . . Specimen Preparation. . . . . . . . Statistical Analyses. . . . . . . . Soils Collection and Analysis. . . . . SOIL TEXTURAL VARIATION AND TREE RESPONSE .IN NORTHWESTERN INDIANA. . . . . . . . Results. . . . . . . . . . . . . . . . Discussion . . . . . . . . . . . . . . Summary. . .-. . . . . . . . . . . . . Page ix 16 23 23 26 26 32 34 35 44 48 50 59 67 TABLE OF CONTENTS——Continued CHAPTER V. REGIONAL CLIMATE AND THE TREE-RING RECORD. . Cross—dating with Negative Mean Sensi- tivity Values. . . . . . . . . . . . . Correlation of Climatic Data with Tree— Ring Indices . . . . . . . . . . . . . Results. . . . . . . . . . . . . . . . Discussion . . . . . . . . . . . . . Physiological Implications. . . . . Ecotonal Implications . . . . . . . Interpretation of the Index Program . . . Results. . . . . . . . . . . . . . . . The Regional Climatic Gradient. . . The Lake Michigan Mesoscale Clima- tic Gradient . . . . . . . . . Comparative Sensitivities of White Oak and Black Oak. . . . . . Discussion . . . . . . . . . . . . . Climate and the Forest Ecotone. . The Lake Michigan Mesoscale Clima— tic Gradient . . . . . . . . Black Oak and White Oak in Future Research . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . . VI. THE LA PORTE PRECIPITATION ANOMALY . . . . Review of the Literature. . . . . . . . Results . . . . . . . . . . . . . . . Correlation of CIimatic Data and Tree— Ring Indices. . . . . . . . . . . . Analysis of Tree-Ring Chronologies . . Discussion. . . . . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . VII. SUMMARY AND CONCLUSIONS. . . . . . . . . . LIST OF REFERENCES. . . . . . . . . . . . . . . . . APPENDICES. . . . . . . . . . . . . . . . . . . . . I. FIELD INFORMATION. . . . . . . . . . . . . . vi Page 68 68 7O 7O 73 73 74 75 75 75 76 86 87 87 88 89 9O 92 92 96 96 98 106 109 115 128 128 TABLE OF CONTENTS--Continued APPENDICES II. III. A. Locations of Sampled Forest Stands. . . . B. Field Data Recording Form . . . . . . . . C. Prominent Plant Species Observed in Sampled Forest Stands . . . . . . . . . . D. Summary Records of Sampled Forest Stands. SOILS INVESTIGATIONS . . . . . . . . . . . . A. Comparative Percentages of Sand, Silt, Clay, and Very Fine Clay in.Pairs of Soil Samples from Selected Sites in North— western Indiana . . . . . . . . . . . . . B. Average Percentages of Sand, Silt, Clay, and Very Fine Clay in Soil Samples from Surveyed Forest Stands. . . . . . . . . . C. Percentage Distributions of Sand Frac— tions in Coarse-Textured Soils from Northwestern Indiana. . . . . . . . . . . D. Stepwise Multiple Regression Analysis Correlations Between Soil Texture Char— acteristics and Tree Response: Stations 5 through 10 Included . . . . . . . . . . E. Stepwise Multiple Regression Analysis Correlations Between Soil Texture Char— acteristics and Tree Response: Stations 1 through 10 Included . . . . . . . . . . CHRONOLOGY INVESTIGATIONS. . . . . . . . . . A. Chronology Parameters for an 81-year Analysis of Variance Period (1890—1970) for Stands of White Oak in Northwestern Indiana . . . . . . . . . . . . . . . . . B. Comparisons of Chronology Characteristics on Contrasting Soil Textures at Selected Weather Stations in Northwestern Indiana. vii Page 129 131 132 133 135 136 137 139 140 141 142 143 144 TABLE OF CONTENTS—-Continued APPENDICES IV. C. Comparisons of White Oak and Black Oak Chronology Parameters from Sites in Northwestern Indiana. . . . . . . . . . . D. Chronology Parameters for 20—year Analy- sis of Variance Periods from Selected Stations and Sites in Northwestern Indiana . . . . . . . . . . . . . . . . . CLIMATIC INVESTIGATIONS. . . . . . . . . . A. Selected Variables for Climatic Analyses. B. Stepwise Multiple Regressions of White Oak Tree—Ring Indices Against Selected Climatic Variables (of the Current and Preceding Seasons) from Stations and Sites in Northwestern Indiana-~l9Sl-l970. C. Stepwise Multiple Regressions of White Oak Tree—Ring Indices Against Selected Climatic Variables from South Bend and La Porte for the Period 1910—1969 . . . . viii Page 145 146 147 148 175 150 VI-l. LIST OF TABLES Page Simple Regressions of Tree-Ring Parameters Against Distance Westward from the Indiana- Ohio State Line. . . . . . . . . . . . . . 85 Changes in Mean Ring—Width After 1930 at Selected Stations and Sites in Northwest- ern Indiana. . . . . . . . . . . . . . . . 103 ix FIGURE I-1. II-l. II-2. III-l. IV-1. IV—2. IV-3. IV-4. IV-5. IV-6. LIST OF FIGURES Study Area-—Location Map. . . . . . . . . Physiography. . . . . . . . . . . . . . . Major Forest Types¥-Location Map. . . . . Survey Locations. . . . . . . . . . . . . Percentage Variance Retained by Groups of White Oak Trees on Contrasting Soil Tex- tures . . . . . . . . . . . . . . . . . . Regression of Percentage of Variance by Groups Against Total Percentage of Fine Materials (Silt + Clay + Very Fine Clay) in the Soil at a Depth of Fifty Inches. . Mean Sensitivities of White Oak Stands on Contrasting Soil Textures . . . . . . . . Regression of Mean Sensitivity Against Total Percentage of Fine.Materials (Silt + Clay + Very Fine CIay) in the Soil at a Depth of Fifty Inches . . . . . . . . . . Cross-Correlation Coefficients Among White Oak Trees on Contrasting Soil Tex— tures . . . . . . . . . . . . . . . . . . Regression of Percentage Variance Retained by Groups Against Percentage of Very Fine Clay in the Soil at a Depth of Fifty Inches. . . . . . . . . . . . . . . Mean Ring-Widths of White Oak Trees on Contrasting Soil Textures . . . . . . . . Computer-Derived Negative Mean Sensitiv- ity Values (1891-1970) from Selected Stands of White Oak Trees in Northwestern Indiana . . . . . . . . . . . . . . . . . Page 11 17 28 51 53 54 55 57 60 64 69 LIST OF FIGURES--Continued FIGURE V-2. V-10. VI-1. Computer—Derived Negative Mean Sensitiv- ity Values (1891—1970) from Selected Stands of Black Oak Trees in Northwestern Indiana . . . . . . . . . . . . . . . . . Mean Ring-Widths Among Stands of White Oak Trees on Fine—Textured Soils at Selected Stations . . . . . . . . . . . . Mean Ring-Widths Among Stands of White Oak Trees on Coarse-Textured Soils at Selected Stations . . . . . . . . . . . . Average Mean Sensitivity Among Stands of White Oak Trees on Fine-Textured Soils at Selected Stations . . . . . . . . . . . . Average Mean Sensitivity Among Stands of White Oak Trees on Coarse-Textured Soils at Selected Stations. . . . . . . . . . . Average Percentage of Variance Retained by Groups of White Oak Trees on Fine- Textured Soils at Selected Stations . . . Average Percentage of Variance Retained by Groups of White Oak Trees on Coarse- Textured Soils at Selected Stations . . . Average Cross-Correlation Among Groups of White Oak Trees on Fine-Textured Soils at Selected Stations . . . . . . . . . . . . Average Cross-Correlation Among Groups of White Oak Trees on Coarse-Textured Soils at Selected Stations. . . . . . . . . . . Mean June—August Precipitation Totals, 1940-1949 . . . . . . . . . . . . . . . . xi Page 71 77 78 79 80 81 82 83 84 94 . ,‘1-1 ".. 3" 'u ‘- ’v an ‘ ) CHAPTER I INTRODUCTION Indiana has been characterized as a dynamic botanical region in which many plant species reach their geographical limits (Lindsey, 1932; Parker, 1936; Friesner, 1937; Deam, 1953; Petty and Jackson, I966). Of particular interest within the state are the three northwestern counties (Lake, Porter, La Porte) bordering Lake Michigan where an inter- fingering of mesic and relatively xeric plant communities is found (Figure I-l). In this tension zone between dif— ferent phytogeographical regions, various ecotones are present (Pepoon, 1927, p. 79; Harman, 1970; Elton 1970a, 1970b). The actual penetration of mesophytic communities to the southwest, or of xerophytic elements to the north- east, is largely determined by local interactions of physical variables such as soil, topography, site history, and possibly local climate (Braun, 1967, p. 322). The purposes of this study are: (I) to assess the role of soils in producing growth stresses in certain plants; (2) to seek evidence from an analysis of stress information pro- vided by tree-ring data as to whether the present distribu— tions of certain mesic communities in northwestern Indiana 23:92.! 1.3 o... 83.: m. o aoahm .1“ MEG; .6 2.23.5 at! ................. 21.52:. 25:25.3 E3238 uEExomdd,‘ IIII .. 385.113 I 5.221191% a mma>h ....mmmom meg—z Nu: LEG: 2 22.55 S w .w . .. ~22 (3.2 .W ..... ..... H. . ................... ES xyukofig tstx _ . ”as. ... 533.”. ........ d “O ........... .. ................................ 3:: o ”B “3.. ........................... ”I. . . 3 SlONl-l'll .................... .. .. .......I'.... ........................................ .....325102 . : 63:33 55.22: . 18 prairies of northwestern Indiana are the result of precipi— tation deficiencies, whereas higher snowfall totals eastward were suggested as the reason for more extensive forests to the east. Transeau (1935), maintaining that climatic factors are more influential than soil factors as prairie determinants, showed that the forest type invaded by prairie communities is always oak-hickory and never beech—maple. Beech-maple was found on sites sufficiently mesophytic to accommodate other species capable of crowding out prairie species; therefore, prairie species invade those forest areas Climatically most similar to the true prairie. Irregularity of rainfall was said to be a critical factor in the maintenance of prairies. Friesner (1937), noting that prairie indicators occur on many different soil textures, concluded that edaphic factors play a minor role in prairie delimitation when compared to climate, especially rainfall. To the contrary, Pepoon (1927) and Bliss and Cox (1964) emphasized edaphic factors in an attempt to explain the presence of prairie communities in northwestern Indiana. Friesner and Potzger (1937) have asserted that the gradual shift from beechdmaple dOminated forests in southern Indiana to an oak-hickory type in the northern one-fifth of the state is brought about by a drOp in average annual rain— fall. According to Potzger and Keller (1952), the oak- hickory forest in northwestern Indiana is a manifestation of climatic controls, the segregation of species within these genera being determined by edaphic factors. Schmelz and 19 Lindsey (1970) attempted to correlate different forest associ— ations with soil moisture qualities. They demonstrated a preference of beech—maple for intermediate positions between very wet or very dry sites. Oak-hickory associations correo lated well withcirier sites. Kilburn (1959) emphasized the importance of t0pography in understanding ecotonal areas in northeastern Illinois. Beech (Fagus grandifolia) has often been categorized as a sensitive indicator of habitat meSOphytism (Potzger and Friesner, 1940; Potzger and Keller, 1952; Friesner, 1942). Rohr and Potzger (1950) and Finley and Potzger (1952) have proposed that the existence of beech and sugar maple in isolated stands west of the general terminus of mesophytic associations is a result of favorable microclimatic condi— tions, and that the distribution of beech suggests a progres- sive change in habitat from west to east. Rohr and Potzger (1950) believed that the sharp demarcation between forest associations in northwestern Indiana is striking evidence of either a climatic or an edaphic selection factor in operation. Friesner (1937) attributed the presence of beech-maple in an otherwise oak-hickory forest type area to soil moisture characteristics. Elton (I970a) suggested that the forest contrast has resulted from an environmental gradient, not variable land-use practices or fire. Several possible explanations of the vegetation patterns in northwestern Indiana may be drawn from the research pre- sented above. First, there are soil variations which may be 20 instrumental in determining plant responses. A notable example may be the abrupt change in forest composition along the Valparaiso Moraine in the vicinity of Valparaiso, Indiana. Elton (1970b) correlated the change in dominance from beech-maple eastward to oak—hickory westward with in- creases in the amount of clay in the soil substrate. Apparently the greater clay content in soils west of the demarcation serves to reduce the readily available water capacity during periods of moisture stress sufficiently to result in the absence of mesophytic species. Second, climatic gradients of diverse proportions and origins which may influence plant distributions exist in this area. Harman's (1970) study of a floristic gradient on the dunes along the southeast shore of Lake Michigan illus- trates one type of climatic influence existing within the study area. Harman noted a change from the dominance of mesophytic species, primarily Quercus rubra (red oak) and Acer saccharum (sugar maple), in Berrien County, Michigan, to a dominance of the more xerophytic Quercus velutina (black oak) in Porter County, Indiana. .He suggested that the lake influence upon nocturnal relative humidity and fire frequency may be causally related to the vegetation pattern. Other Studies actually demonstrating relationships between ecotones and climatic variables in the region are rare. A third possibility concerns the relationship between vegetation patterns and the present climatic regime. A pro— cession of climatic changes is believed to have taken place 21 in the region during postglacial times, but the sequence of change is still subject to question. It is generally con- ceded, however, that gross changes in vegetation patterns occurred after deglaciation in response to climatic fluctua— tions (Dillon, 1956). Most research confirms the presence of a spruce and fir belt in the Central States area which followed the re- treat of the glacier northward and persisted until about 8,000 years ago (Potzger, 1946; Deevey, 1949; Davis, 1967; Durkee, 1971). Zumberge and Potzger (1956) established a chronology from pollen strata in southwestern Michigan which shows a pine stage replacing the spruce-fir forest and remaining until about 5000 years ago, when oaks came into prominence. An oak-hickory—broadleaved forest maximum (4,000 years ago) was succeeded by an oak-hickory maximum (3,500), presumably as climate became increasingly warmer and drier. A number of other studies in the region support this overall sequence (Guennel, 1950; Just, 1957; Brush, 1967; Durkee, 1971). But Davis (1965) cautioned against drawing broad vegetational or climatic generalizations from pollen analyses; and Benninghoff (1963) projected the entry of mesophytic species (especially beech) into northwestern Indiana from Michigan about 3,500 years ago, which appears inconsistent with the generally prOposed warm, dry climate accompanying the oak-hickory stage. In addition, Benninghoff contended that an earlier southern migration of beech into 22 the area had been blocked by a postglacial prairie peninsula. Friesner (1937) contended that at least a part of the coastal plain flora in Indiana are still in the process of migrating toward a potential western limit. Elton's (1970b) suggestion of an edaphic, not climatic, control of the sharp demarcation between beech-maple and oak—hickory along the Valparaiso Moraine was discussed earlier, and Finley and Potzger (1952) have documented the presence of isolated stands of beech and sugar maple west of the main beech-maple forest. Several researchers (Cowles, 1901b; Fuller, 1925) have predicted an eventual migration of the beech-maple type from its present position. But Potzger and Friesner (1939) believed that the area occupied by beech has recently been decreasing. From the evidence presented above, it seems certain that vegetation and climatic patterns in the Great Lakes Region have undergone large-scale changes since glacial retreat. And further, there appears to be justification for considering the possibility that present floral distributions are not in complete agreement with existing climatic condi- tions. CHAPTER III METHODS Physiological Foundations of Dendrochronology Early in the 20th century, Dr. A. E. Douglass, an astronomer, presented evidence revealing that the widths of annual rings in trees in semiarid sites correlated with variations in climate. The pattern of wide and narrow rings was so pronounced that he was able to recognize and cross— date the same pattern in tree stumps from nearby areas and to determine the year of tree removal (Douglass, 1919). Following these discoveries, a systematic tree-ring research program was undertaken, the result being the development of a discipline termed dendrochronOlogy, and the establishment of a tree-ring research laboratory in Tucson, Arizona under the auspices of the University of Arizona. Broadly speaking, dendrochronology may be defined as the study of yearly growth patterns in trees and their use in dating past events and in evaluating past climatic fluctuations (Fritts, 1966). Tree— ring relationshipsare readily measured and tested by quanti— tative methods, and results are interpretable in terms of modern physiological principles. 23 24 A tree stem increases its diameter annually through the formation of a growth ring ("tree-ring") inside the bark by division of cambial cells; upon division, cambial cells produce large, thin-walled xylem cells (earlywood) in the early part of the growing season and small, thick- walled xylem cells (latewood) as the growing season nears an end (Wareing, 1951; Larson, 1962b). The latewood portion of the total annual tree—ring increment appears to be very closely related to conditiOns during the current growing season (Byram and Doolittle, 1950; Smith and Wilsie, 1961; Kennedy, 1961; Jackson, 1962; Zahner g§_al., 1964) and commonly exhibits a greater degree of year—to-year varia- bility than earlywood (Bannon, 1962). Earlywood growth typically is only slightly related to current growing season conditions (Lodewick, 1930; Schulman, 1942; Byram and Doolittle, 1950; Woods and Debrunner, 1970), but climatic conditions of the September preceding growth often strongly influence earlywood development (Diller, 1935; Schumacher and Meyer, 1937; Hansen, I941; Fritts, 1958; Gagnon, 1961). The dimensions of individual tree-rings are a function of the tree's heredity and environment acting throughout any given growing season (Kramer and Kozlowski, 1960, p. 428). While the relationships between tree growth and external environmental elements are complex and not fully understood, physical variables such as soil moisture, temperature, and photoperiod apparently exert indirect dominance over certain physiological processes, often through the creation of 25 moisture stress within plants. Internal moisture stress readily limits two major processes essential for the diame— tral increase of tree stems: photosynthesis and production of growth—regulating hormones (Kramer, 1958, ch. 8; Larson, 1962a). The close relationship between environmental controls and arboreal diameter change has been demonstrated in many studies. Mikola (1950), studying conifers in northern EurOpe, determined annual diameter increment to be dependent upon temperature characteristics of the current growing season; MacDougal (1938) noted a close correspondence between available moisture and diameter increase in several Pacific Coast oak species; and Fraser (1962) found a close correlation between soil moisture and cambial activity in several tree species including northern red oak. In North Carolina, Woods and Debrunner (1970) concluded that total annual radial growth of loblolly pine is influenced by the same factors that influence latewood growth, primarily the availability of soil moisture late in the growing season. An actual decrease in diameter during drought in white pine, black locust, and beech was observed respectively by Freisner and Walden (1946), Daubenmire and Deters (1947), and Fritts (1958). Jackson (1952) recorded daily radial shrinkage in white oak, northern red oak, and southern red oak during periods of moisture stress, and Friesner (1942) recognized linkages between growth of beech in Indiana and clbmatic factors of the current growing season. Thus, relationships between environmental parameters and diametral o an"; in. do 0 9‘ ‘10 (D (I. ”A. .U '5 ‘ a ‘In N. g In.“ ‘ I-“" w...‘ “‘~ ‘5... 4 \‘u ‘1 (I. 26 development of trees are well documented, and one objective of dendrochronology is to assess the strength of these relationships. In summary, the change in cell-size from earlywood to latewood in trees is a gradual process, and the structural changes and total number of cells within a growth-ring depend upon the environmental and physiological factors that have limited the rate of cell division and enlargement. Therefore, both ring-width and cell structure can be prod- ucts of environmental influences which are present before and during the growing season. Dendrochronological tech— niques provide a means of assessing long-term environmental controls of tree response through measurement of yearly ring-width variability. Procedures in Tree-Ring Analysis Site Selection Selection of forested tracts for use in this study was based upon the following criteria: soil drainage and textural uniformity; topography; distance to weather sta— tions; and size, age, and degree of disturbance of forested stands. A11 field observations and data gathering were completed during the summer of I971. The following National Weather Service stations were selected as sources of rainfall and temperature data to be applied in subsequent correlations with appropriate tree- ring indices: South Bend, La Porte, Michigan City, Wanatah, 27 Valparaiso, Wheatfield, Ogden Dunes, Hobart, Lowell, and Park Forest. The relative locations of these ten stations were believed to be sufficient to provide adequate dendro— clflmatological data coverage for analysis of climatic pat- terns in northwestern Indiana. Near each weather station four forest stands (Figure III—1) were sampled for collec- tion of tree cores (if stands meeting certain site require— ments could not be located within a two—mile radius of a weather station, then fewer than four stands or slightly more distant sites were used). The selection of multiple woodlots around weather stations served several purposes. One purpose, to be dis- cussed in depth later, was to detenmine the relative roles of soil textural variation in affecting tree—response (climate was assumed to be constant around each station). A second purpose was to determine whether or not cross- dating, a basic dendrochronological concept, exists among sites around individual stations. Cross—dating assumes that recognizable and synchronously matched variations in ring-width among trees from a local area are evidence of some general environmental control(s) (Schulman, 1950). If cross-dating exists, meaningful analysis of climatic variation may be possible with tree—ring techniques. For any given weather station the first step in selec- ting woodlots for sampling was the careful examination of county Soil Survey maps, Soil Conservation Service (SCS) field and interpretive sheets, and t0pographic maps. 28 292 85249.: g «uhzwo :6 o ozfim Sumo... award...” . 2955 5.12“...) 4 mzo_._.<00n_ >m>m=m TE mung... ----------------- ‘ d 3.3 o 5296.??? .Io_s_ why—0&4... 14224; a. ‘o. o o n h 56de m... 3.1.. ..m to 23.5.2 o. ... ..c o o a . _ I I o 3 a 32.1591: ‘ c -o nu 0388.3 0 ON. 4: m m \ $3352; ...... m. \\\\\ x \ 8.43543 ... \\\.E< 'N" zmooo n3 . .. \ <3. 8..\ ...JMBOJ‘ _ Area \\\w....... . . ., \ \\\... ,\.. .... \.\\ \. x. \. \\ . \ \ ..\ \.\\...\ ...x. \x\\ \\\. \\ ..\ .. .\\ x. \, .. . .\.\.,..\. .\. .. \\\\\. \ . . . .. .555... 55....5...‘ . . \ ..\\\\\\g s . .. \ . . . .. . \ \ \\x§ \ \.\M..\ I. u..”' . .\\\ ~ a... .\ .\ . .. \ .\\\\._ £8. \ \w . oooozx on. . o an a a .. 29 Where available, the field sheets (aerial photographs with superimposed soil mapping units) were especiallyhelpful because they included photographs of forested tracts as well as soils information. In the initial phase of site selection, drainage, topography, textural uniformity, and distance to weather stations were important considerations. Most researchers seem to agree that tree response increases with drought stress; thus, an effort was made in this project to select only sites where drought stress was maximized, that is, well-drained sites where a wet soil profile for long periods during the growing season had not been a confusing factor. Under well-drained conditions, trees are more likely to respond directly to immediate climatic conditions, showing a pronounced pattern of common variation particularly in years when moisture approaches the limits of tolerance (Schulman, 1950). As outlined in the Soil Survey Manual (U.S.D.A., 1951, pp. 205—13), field determination of soil textural classes to a depth of 50 inches was made mainly by rubbing moistened samples between the fingers and estimating relative size distributions from a textural triangle chart. This procev dure provided a fast, reasonably accurate means of keeping soil variability to a minimum. Where possible, at least one site per weather station that was texturally akin to sites of surrounding stations was selected in order to establish linkages across the study area. Signs of subsoil reduction 30 processes provided a means of detecting an insufficiently drained site. Even though some mottled colors may occur unassociated with current incomplete drainage (Simonson, 1951; Ruhe, 1956), imperfectly and poorly drained soils are nearly always mottled with various shades of gray, brown, and yellow, particularly within the zone of periodic water table fluctuation (U.S.D.A., 1951; Wilde, 1958; Millar .§§_gl., 1965, p. 253). Study sites were limited to generally level or rolling topography because of the likelihood of eccentric ring development in trees growing on steep slopes. Frequently, leaning trees, or trees on strongly sloping surfaces, produce irregular growth—rings because of an unequal weight distribu- tion within the tree bole (Bauer, 1924; Wardrop, 1965; Stokes and Smiley, 1968, p. 31). Apparently no definite conclusions have been reached in defining the distance from weather stations at which agreement between recorded climatic data and tree—ring varia— tion may be expected to decline, although inferences may be drawn from two recent articles. Extrapolating from the work of Julian and Fritts (1968) in C010rado, a spatial decay of the ring index to precipitation index relationship was indi- cated at approximately 15 miles in several conifer species. Estes (1970) correlated precipitation periods and ring indices of white oak in the Central Mississippi Valley and found coefficients averaging .54 at a distance of 40 miles from stand site to rain gauge; but, at 60 miles correlation 31 coefficients had dropped to an average of about .20. In an area as Climatically and botanically complex as northwestern Indiana, distances approaching those discussed above probably would have been excessive. Therefore an arbitrary 2—mile radius was set for this study in an effort to reduce unwanted variation resulting from distance decay factors. Following delimitation of potentially suitable areas, acceptable forest stands were subsequently identified by automobile reconnaissance. Woodlots were appraised for in— clusion in this study on the basis of four criteria. First, at least eleven dominant or codominant white oak trees that had not been visibly disturbed by conditions arising beyond the woodlots' margins ("edge effect") had to be present. Second, basal area had to be comparable to surrounding sample sites, for the purpose of maintaining relatively uniform stem size-classes among the different forest stands across the study area. Although no precise limits were set, basal area of most stands was within the 100-115 ft2 range. Basal area was determined with a Cruz-A11 aperture angle gauge for point sampling. Third, only trees dating at least to 1885 were considered, as determined from a sample core. The fourth criterion, degree of disturbance, was more difficult to evaluate. All of the forest stands in the study area probably had been disturbed by human activity to some degree. Stands under consideration were assessed by inspec— tion and in many cases through interview with the owners. a\-n “ d“ A ‘ I‘l h» N '1 32 Where severe grazing, cutting, or burning was evident, these stands were omitted from the project. At this point, forest stands were judged acceptable for inclusion in the project. After acceptance of a stand, a description of site characteristics was entered on a specially prepared form (Appendix I—B). Specimen Collection The final step in field data collection was the extrac- tion of tree-cores and subsequent plugging of the small holes made by the extraction instrument (to reduce the possi- bility of damage to the trees by insects and decay-causing organisms). Sampling procedures used in obtaining tree-cores for this study were derived at the Laboratory of Tree—Ring Research. From each forest stand, one core from the north and south radii of eleven dominant or codominant white oak trees (Quercus alba) were extracted at breast height (4.5 feet above ground) using a 16 inch Jim-Gem increment borer lubri- cated with beeswax. The number of trees and cores per tree needed to comprise a valid sample has been questioned. Schulman (1942, 1945) used only one core per tree, but Lyons (1939) demonstrated that trees growing on slopes, ridges, or sites with variable depths of shallow soil are likely to grow at uneven rates on different sides of the tree. Lyon recommended using three radii evenly spaced around each tree, .0 .v u I 0‘. \n. ‘ I ... \- a 's nlv \n‘ 33 as did Schumacher and Day (1939). Lodewick (1930) undertook a tree-ring analysis with four cores per tree representing the cardinal campass directions, but he found no significant differences among the cores resulting from slope, longer exposure to sun on south and west sides, and crown size or asymmetry. He concluded that one core per tree is sufficient in dendrochronological research. More recently Fritts gt_al. (1965) studied a vegetation gradient in northern Arizona taking four cores from five mature trees in selected conifer stands. But in subsequent studies in the same general region, Fritts (1965, 1966) changed to what was considered to be a more representative sampling procedure of regional tree-growth patterns by remov— ing two cores from each of ten trees. This latter method has been applied by Julian and Fritts (1968), Schultz §t_§l, (1970), Woods and Debrunner (I970), Herman and Ddflars (1970), and Harman and Elton (1971). In addition to taking several tree cores from each tree, multiple trees from each site must be sampled. The purpose in Obtaining specimens from more than one tree is to check the ring record of any tree against sufficient associated trees for the calculation of a group mean in which random errors have been cancelled as far as possible. The group mean then may be correlated with climatic data and/or may be analyzed with established dendrochronological methods. The replication of samples by collecting two cores from each 34 of ten trees per sampled site is now standard procedure at the Laboratory of Tree—Ring Research (Fritts, 1969). Specimen Preparation Following extraction, the tree cores were stored in plastic straws for transportation in the field. Later, to prevent warping the cores were removed from the straws and lashed into specially designed wooden trays for drying. Individual trays were identified as to station, tree, and core. After the cores had dried, they were glued into the trays with each core positioned to exhibit a cross-sectional (transverse) view on the exposed surface for maximum ease in distinguishing annual rings. once the glue had set, the core surfaces were prepared for measuring. Several procedures for preparing core surfaces have been devised (Glock, 1937, pp. 5-6; Stokes and Smiley, 1968, pp. 37-46; Estes, 1970). ‘The method used in this study was modified from Estes (1970) and consisted of the following steps: (1) core surfaces were flattened with fine grit (#150) aluminum oxide abrasive on a Black and Decker orbital finishing sander; (2) the flattened surfaces were further smoothed with extra fine grit (#220) aluminum oxide abrasive on the orbital finishing sander; and (3) the smoothed core surface was rubbed lightly by hand with very fine steel wool (#000) to remove the dust from tracheid Openings. Annual rings were more distinct in cores prepared with this technique 35 than in experimental cores which had been planed with sharp instruments. Next, randomly selected cores from a number of woodlots across the study area were examined for age determination; most of the younger woodlots dated from about 1885. Thus, in order to preserve age uniformity among sample data all chronologies were begun at 1890 and continued through 1970. The eighty-one annual rings for this period from each core were measured to the nearest hundredth-millimeter with a DeRouen Dendro—Chronograph (20x magnification) and registered on FORTRAN coding forms; each tree—core was identified by a six-digit number representing the weather station, woodlot, tree, core, and species. To assure that tree-rings were being accurately distinguiShed with the dendro-chronograph, cross-dating procedures established prominent sequences of wide and narrow rings. When the twenty—two core chronologies (eleven trees) for a woodlot had been measured, ten trees were chosen to represent the stand. This procedure permitted the omission of tree-ring records shorter than eighty-one years, chronologies obscured by internal damage, and chronolo— gies noticeably different from other trees sampled at that site. Statistical Analyses .Tree-ring measurements for the twenty cores from each site were transferred from the FORTRAN coding forms to punch cards for subsequent computer processing. Several programs 36 adapted to an IBM 6500 computer were obtained from the Laboratory of Tree-Ring Research for analyzing the changes in tree—growth linked with increasing age (Matalas, 1962; Julian and Fritts, 1968). Normally, diameter growth, although affected by many factors, tends to follow a pre— dictable trend in undisturbed trees. At the seedling stage, the first increments are frequently very small until the tree has become established. subsequent tree—rings increase in width as the tree rapidly enlarges; but as the tree grows older, ring-width gradually decreases (assuming uniform grow— ing conditions) because yearly increments must be spread around increasingly larger stem circumferences (Gessel‘e§_al., 1960, p. 13). Typically the growth curve for the outer portion of the tree can be approximated by a negative expon- ential curve or a straight line. However, disturbances such as lumbering which open the forest canopy normally create a sequence of enlarged tree—rings which are not satisfactorily approximated by the negative exponential curve or straight line and which may bear little relationship to the climatic record. For this reason obviously disturbed woodlots were avoided, and in three cases foIIowing examination with the dendrochronograph, forest stands bearing clearly aberrant chronologies were not included in further analyses. camputer analysis of the tree—ring data proceeded in six general steps: 1. A Ring Width Listing Program (RWLST) was applied to selected woodlots from across the study area primarily for 37 indications of suspected disturbance. Input for RWLST con- sisted of the previously assigned six-digit identification number and the annual tree-ring measurements for the period 1890-1970 for each core. Output included a listing of all annual ring-widths of each core by lO-year intervals and the computation of 20-year running mean ring—widths and mean sensitivities (a year—to-year variability measure) at 10- year intervals. .RWLST also computed the slope of a regres— sion line fitted to each 20-year period, and summarized the mean ring-width and mean sensitivity for the complete series (all the ring-widths for any core) as well as a plot of the 20-year running mean ring-widths. Ordinarily RWLST is useful in checking for errors in dating, measuring, card punching, and detecting trees with unusual growth characteristics. 2. The Tree-Ring Index Program (INDXA) processed the same raw data as RWLST and provided the basic statistics for ensuing analyses. In raw form, tree—rings from different cores and/or trees cannot be compared. The primary function of INDXA was to convert raw ring—widths into standardized indices, and in so doing, to attempt to remove non—climatic trends (for example, disturbances or unequal growth rates) from the chronology. Through the standardization of indi- vidual tree-rings, different core chronologies could be analyzed and compared. INDXA read the raw ring-widths for each core, and then applied a least—squares technique to fit a negative exponential curve approximating the expected decreasing ring-width associated with increasing age to the 38 tree. If this curve was inapplicable, a straight line of any slope was fitted to the data. The observed ring-width for each year was divided by the value of the fitted curve fOr that year to obtain a ring-width index. The resultant indices for each core had a mean of unity and a variance non—dependent upon tree age, position within the stem, and mean growth rate of the tree (Julian and Fritts, 1968). The average index for each year then was calculated from the indices of the twenty cores for each group to form a standardized tree-ring chronology. In addition to calculating yearly indices, the deviation of the ring-width from the curve, the mean sensitivity, and the square of the index were calculated and printed for each year. At the end of each series the first order serial correlation (which measures the non-randomness of tree-rings from one year to the next), standard deviation of indices, mean sensitivity, mean index, sum of indices, sum of squares of indices, and the type of regression fitted by the computer were printed. In order to obtain a group chronology for any given site, INDXA required a sequence of series summaries which includes (1) both cores from each of the ten trees; (2) the north core from each of the ten trees; (3) the south core from each of the ten trees; and (4), both north and south cores from all ten trees. The final summary constituted the mean ("group") chronology for that site. For each of these 39 summary steps, the mean indices, statistical error, standard deviation, variance, square of index, number of cores, sum of indices, and sum of squares of indices used in each summary were listed. INDXA also provided punch Options for core indices, summary indices, and means of squares of com- ponent summaries for application in subsequent computer analyses. 3. The Analysis of Variance Program (ANOVA) was actually a subroutine of INDXA, which applied the mean indices and sums of squares of individual core chronologies produced by INDXA to calculate the estimated mean squares and the vari- ance component for the chronology of individual radii sampled per tree, individual trees, the total sample, and combina- tions of the preceding (Snedecor, 1956, Ch. II). The printed output from ANOVA contained the raw sum, corrected sum, degrees of freedom, mean squares, and percent of estimated meanvsquares, and percent of estimated mean squares for the core, tree, and groupchronologies. .By definition, the estimated mean squares (EMS) provided an estimate of the variance component for each chronology (Klausmeier and Goodwin, 1961, p. 677), and the percent of estimated mean squares (PC EMS) indicated percentage of the variance arising from differences in chronologies along several radii (YCT), and differences in chronologies among .individual trees (YT), as compared to the remaining varia- bility in the group chronology (Y). These figures were 4O helpful in assessing the relative proportion of ring-width variation shared by all trees in the group (Y) as compared to the differences among trees (YT) and the differences be— tween radii within trees (YCT). Thus, the analysis of vari- ance facilitated the evaluation of relative differences and similarities in growth response of trees to their environ— ment (Estes, 1970). Four chronology parameters produced by INDXA and ANOVA-—variance, percentage of total pooled variance con- tained in the standardized group chronology, serial corre- lation coefficient for the chronology at a lag of one year, mean sensitivity-—were potentially useful in estimating the responsiveness of tree-ring series to growth conditions. The reasoning behind this estimation was as follows: trees (individuals or groups) which are limited frequently by moisture stress show a larger relative variability from year-to-year in tree—ring widths than those which are less often limited. In the latter, the combinations of soil moisture and temperature probably have not been sufficiently extreme to limit growth, and the factors determining growth apparently vary little from one year to the next. Trees restricted by moisture stress usually exhibit similar pat- terns of wide and narrow rings in all sampled trees from a given site. This similarity was measured by the percentage of total variance appearing in the group chronology (Y) (Julian and Fritts, 1968). Finally, changing rates of growth 41 in parts of individual cores may have been caused by altera- tion of site factors not related to climate (fire, lumbering); and there may have been physiological feedback mechanisms operating independently of climate which prescribed that wide rings be followed by wide rings and vice versa. The first order serial correlation coefficient (Ouenouille, 1952, pp. 166-68) yielded a measure of these linkages in adjacent ring— widths which could have complicated desired statistical relationships (Matalas, 1962). Removal of residuals arising from serial correlation allowed a more precise determination of important environmental parameters (Fritts et al., 1965). Mean sensitivity is an indication of the relative change in ring index from year to year and was calculated as the absolute difference between adjacent indices divided by the mean of the two indices (Fritts et al., 1965). Individual mean sensitivity indices were averaged to produce a mean value for the entire series. Theoretically, mean sensitivity may be used as a quantitative index of external stress-— spatially or temporally. For example, if a general climatic gradient existed across the study area, mean sensitivity should show concomitant changes. Or, if mean sensitivities before and after 1930 at La POrte were markedly different, the implication would be a temporal change in climate. Therefore, variance, percentage variance maintained by the group, serial correlation, and mean sensitivity were each potentially important statistics in approaching the 42 climatic, edaphic, and phytogeographic questions outlined for this project. 4. The Cross—Correlation Program (XCORR) was another subroutine of INDXA. XCORR calculated inter- and intra- correlations among series for individual woodlots. Inter— correlation represented the mean of all possible linear correlations between tree chronologies within a group of trees, whereas, intra—correlation determined the mean of all possible correlations between radii within individual trees. The Inter—correlation coefficient was especially useful because it indicated the relative degree to which a group of trees was responding together to common environmental stresses. Both coefficients theoretically should have shown positive variation with moisture stress. 5. A Stepwise.Multiple Regression Analysis (STEPR) correlated tree-ring indices of selected woodlot chronolo- gies with selected monthly climatic variables representing the year of tree growth and the year preceding growth. After analyzing a statistical relationship between a dependent variable (yearly tree-ring indices) and a set of independent variables (climatic data), STEPR listed the independent variables in order of importance. The criterion of impor- tance was based upon a reduction of sums of squares technique, and the independent variable most important in this reduc- tion at a given step is entered in the regression (Wittick, 1971). 43 A stepwise multiple regression analysis offered several desirable features for this project. First, the capacity of this manipulation for handling relatively large numbers of variables was essential for studying climate and growth relationships. Even though in some situations one climatic element may be dominant, more often in middle latitudes tree growth is a complex function of interacting factors (Kramer and Kozlowski, 1960, p. 428). Therefore, a statisti— cal analysis capable of combining the statistical influences of multiple factors was more appropriate than a simple re— gression analysis (Fritts, 1962a). And second, the procedure has been applied with apparent success in a number of studies seeking to correlate tree growth and weather data (Fritts, 1962b; Fritts, 1965a; Fritts, 1969; Woods and Debrunner, 1970; Harman and Elton, 1971). A possible disadvantage of a stepwise multiple regres- sion technique was an inability to identify common sources of variance among independent variables (Cole and King, 1968, Ch. III). In other words, significant correlations between monthly precipitation and temperature could exist undetected which might yield unrealistic correlation coef- ficients in the final analysis. However, results from the studies cited above do not suggest this problem. Employing :a principal component analysis to examine the inter-corre- lation of precipitation and temperature data from Colorado, Julian and Fritts (1968) concluded that multicollinearity 44 was of minimal importance. Therefore, the possibility of multicollinearity between temperature and precipitation data from northwest Indiana was recognized, but it was not be— lieved to be a serious concern. To briefly summarize the procedures of statistical analysis, six computer routines were adapted to an IBM 6500 computer. Following a data listing of selected woodlots, eighty-one yearly raw ring-widths from twenty cores (ten trees) per stand were standardized and averaged to form a mean group chronology. Several measures of tree—ring series sensitivity were derived for each core, tree, and woodlot, and their likely application to questions being considered in this project was discussed. The final step applied a stepwise multiple regression analysis for correlating tree response with selected climatic variables in an attempt to ascertain important plant—climate relationships in north— western Indiana. Soils Collection and Analysis At each site soil samples were collected with a bucket— type soil auger for an indication of subsurface drainage and textural composition.' The number of test borings made in any location varied depending upon characteristics of the site, but usually five borings were made. (In some instances where unsuitable site qualities were suspected as many as ten samples were examined.) As discussed previously, only well- drained sites with apparently uniform textures were acceptable 45 iEor data collection. From two borings soil samples were taken at three depths: the upper solum, or A horizon, the :zone of apparent maximum clay accumulation in the B horizon, and the level immediately below a depth of 50". These six samples were stored in individual plastic bags for analysis at Michigan State University. Samples taken below the 50" level were tested in the field with dilute hydrochloric acid. At the university, all samples were analyzed to deter— mine their particle size distributions according to the Bouyoucos hydrometer method (Forest Soils Committee, 1953; Day, 1965) with several modifications. First, the readings customarily taken at 270 minutes and 720 minutes were re— placed by one reading at 480 minutes. For purposes of this study, the 480 minute reading defined the very fine clay fraction of the soil sample. Second, the 480 minute read— ing was subtracted from the 120 minute reading to determine the clay fraction. (Thus, the very fine clay fraction and the clay fraction together comprised the total clay content of the soil sample.) Finally, the silt fraction was determined by subtracting the combined percentages of sand and clay from 100 per cent. The Bouyoucos system has been demonstrated to be accurate and detailed enough for most analyses of forest soils (Gessel and Cole, 1958). For approximately one-tenth of the samples duplicate analyses were run to assure congruity of measurement: however, since corresponding results were quite sflnilar 1n 46 tihese cases, complete replication was not performed. Ilnitially the two soil samples at corresponding depths from (each site were analyzed separately, compared, and then averaged to provide mean values for individual textural components. Later, after sample pairs had proved to be in close agreement (Appendix II-A), the two samples were physically combined prior to running a single Bouyoucos analysis. Final results of the soil textural analyses are given in Appendix II-B. Soil texture was deemed important for this study because evidence suggests that it is an im— portant prOperty in controlling the available moisture within a soil, perhaps the single most important such prOperty (Lund, 1959; Petersen and Cunningham, 1968). Several procedures were adapted for the study of rela— tionships between tree response and soil textural variation. Results of the soil textural analyses were entered against a parameter representing tree response from each stand in a stepwise multiple regression analysis program in order to determine which, if any, of the textural components might be significantly related to tree growth across the study area. Simple regression analyses of tree response against specific .textural fractions (for example, very fine clay) supple- mented the findings of the stepwise multiple regression tech— nique. In addition, previously discussed tree-ring parameters provided a basis for making inferential statements. T0 illus— . . . t trate, assuming that climate was uniform for the four “00610 s \VR" A 2 65" ‘II 47 zixound each weather station, differences in cross—correlation czoefficients or percentages of variance shared by groups vvere considered evidence of relative influences of soil ‘variability. Estes (1970) made a similar assumption. CHAPTER IV SOIL TEXTURAL VARIATION AND TREE RESPONSE IN NORTHWESTERN INDIANA One purpose of this study was to search for tree-ring evidence as to whether the western boundary of the beech— maple forest in northwestern Indiana is fixed by environ- mental limitations, or whether the boundary is the result of incomplete adjustment to conditions following the Pleistocene Epoch. There is little doubt that an east-west climatic gradient encompasses the study area, but the phytogeographi— cal importance of this gradient is largely undetermined. The problem is complicated by a general difference in soil textures east and west of valparaiso; this change in soil textures as mapped in Soils of the North Central Region of the United States (1960) corresponds closely with the change in forest composition from meSOphytic to the more xeric vege— tation types. Thus, the problem became one of evaluating the relative influences of climate and soils upon tree growth through an analysis of the tree-ring record. Since soil patterns across northwestern Indiana are complicated, the first step was to assess the rOIe of soils in producing growth stresses, so that the influences of climate could be better understood. 48 9 ‘C. - Ia“ QR *Ub ‘ r- .00 N “' g 49 As described in detail in Chapter III, the analysis of variance deve10ped by Fritts (I963) for tree-ring studies is an objective method of analyzing large amounts of data and comparing relative growth responses from many different locations. Fritts (1963) and Estes (1970) have demonstrated that the estimated variance components may be especially useful in evaluating the relative similarities and differences in tree—growth response along climatic, edaphic, or biotic gradients. As a general rule, trees limited by environmental stress exhibit similar patterns of wide and narrow rings in all sampled trees from a given site. This similarity is expressed by a high percentage of total variance appearing in the group chronology. Fritts (1965a; 1965b) and Estes (1970) observed that disturbances by fire or cutting could alter the group chronol- ogy and increase the percentage variance among trees and radii. The preceding observation may be an accurate assess— ment when only a few trees in a stand have been affected; but in the present study large-scale disturbances resulted in inflated group variances. Therefore, since disturbance seemed to distort the analysis of variance values, stands #3, #12, and #13 which were severely disturbed (as determined by examinations of tree cores, variance components, and standard errors) were omitted from further study. n-(u‘ ~'t.‘ 0 Bl' ll) l 0 Ill 9‘ . id ~~" fin”! .Vh. "uh . P; (‘0 Ya. I ‘el r) 0 LI) '1 L.) O". (I) 50 Results Appendix III-A provides a listing of the variance com- ponents for individual forest stands across the study area, as well as a summary of other important statistical para— meters provided by the INDXA computer routine. The data in Appendix III—A,'and succeeding figures derived from this table, may be used to evaluate the response of forest stands to the environment; but because of the high variability in many of the site records, great care must be used in inter- preting these data. The reasons for this high variability are not entirely evident; a comparison of variability among the stands on similar soil textures at nearly any one of the weather stations, where climate is assumed to be constant, suggests that the unexpected differences in chronology sensi- tivities are the result of site factors such as undetected disturbances and impeded subsurface (below 50 inches) drain- age. Figure IV-l depicts the trend of the percentage of variance retained by the group in white oak stands across the study area arranged according to gross soil texture. An important feature of the chart is the generally higher group responses on the finer-textured soils compared to the coarser soils. While the significance of the differences in. response between stands growing on contrasting soil textures around individual stations could not be determined because of sample size, a simple regression of percentage of variance 5° mo~.°LMV >5 Umwcunvhcm ECCU~L~L> QUEsccnvLcl s \Ih -.\-u-s\ 51 33 mm mehwa mmmH mung... no. :8 -on .or. now now ..om ... co. (dflOH9) 30NVIUVA 1N3383d retained by groups across the study area against the per- centage of fine material (silt, clay, and very fine clay) in the soil at a depth of 50 inches yielded a highly significant statistical relationship (Figure IV—2). The higher variances and lower standard errors on the majority of finer-textured soils demonstrate the relatively high similarity in growth response for all trees at each of these sites. Most of the finer-textured soils were taken from the western part of the study area, but several of the highest values were obtained from more easterly sites at Valparaiso, site #8, and Michigan City, site #10 (53% and 47% respectively). Mean sensitivities and cross-correlation coefficients were analyzed by the techniques used in the preceding para- graph. The trend of mean sensitivities was inconclusive, if not unexpected (Figure IV43), and the statistical relation— ship between mean sensitivity and soil texture was not sig— nificant (Figure IV-4). Aside from wide variability, especially on the coarser soils, and an apparent absence of trend on either texture, mean sensitivity values often did not appear to accurately reflect stress as indicated by the percentage of variance retained by the group. For example, in comparison to other sites at Park Forest, the percentage of variance retained by the group at site #34 appears to be rather insensitive (Appendix III-A); yet, the mean sensitivity value was relatively high. An examination of Fritts' (1965a) and Estes' (1970) mean sensitivities indicates PERCENT VARIANCE (GROUPS) 66.3- 60.6‘ 55.0‘ 49.3" 43.7- 38.0 '- 32.4" 26.7‘ 2|.l " l5.4- 9.8 - 53 FIGURE IV-2 Regression of Percentage Variance Retained by Groups Against Total Percentage of Fine Materials (Silt+ Clay+ Very Fine Clay) in the Soil at 0 Depth of Fifty Inches r = 0.59 Sig. of F: (0.0005 I I l I l l I l I.6 IO.6 l9.6 28.6 37.6 46.6 55.6 64.6 73.6 82.6 9|.6 PERCENT FINES go I‘ sl- . o‘I MEAN SENSITIVITY .26- .24‘ .22‘ .20‘ .06- .04- .02 - 54 FIGURE IV-S Mean Sensitivities of White Oak Stands on Contrasting Soil Textures NE SW I I I l I I la 0 I l I ' ' II I I I I | I I I i I I2 4 9 IO ll l4 I5 I6 I? I8 I920 2| 22232425262728 29303| 323334 STAND NUMBER FINE TEXTURE '---- COARSE TEXTURE MEAN SENSITIVITY 0.2l - 0.20 - O.|9" 0.I8" OJ?" 0.I6 '- 0.!5- 0.I4" 0.I3"‘ O.I2‘ O.|| - 55 FIGURE rv-4 Regression of Mean Sensitivity Against Total Percentage of Fine Materials (Silt+ Clay+ Very Fine Clay) in the Soil at 0 Depth of Fifty Inches r = 0.l6 Sig.ot F: 0.376 I l I I I I I I I I |.6 I0.6 I9.6 28.6 37.6 46.6 55.6 64.6 73.6 82.6 9L6 PERCENT FINES 56 similar inconsistencies. On the other hand, the trends of cross-correlation coefficients among trees (Figure IV—5), a statistic rarely cited in the literature, bear a remark- able resemblence to the trends of percentage variance main- tained by the group (Figure IV-l). Individually, or collectively, the cross-correlation coefficients appear to be highly supportive of percentage variance components. This fact probably should not be surprising, since both statistics are a measure of shared variation among trees at individual sites. In future dendrochronological research, cross-correlation coefficients may be a more useful statistic than mean sensitivity when analyzing groups of trees. Appendix III-B depicts several stations where both fine— and coarse—textured soils were sampled. A comparison of statistics between individual woodlots at each station reveals that in every case the percentage of variance main- tained by the group is higher on fine—textured soils than on the coarser soils. Most of the other comparative para— meters in the table, except serial correlation coefficients which showed no consistent trend among stands, seem to indi- cate further that stress is more pronounced on the finer— textured.soils. In a further attempt to define the relationship between soil textural variation and phytogeographical patterns in northwestern Indiana, the stepwise multiple regression analy- sis program described in Chapter III was applied. CROSS- CORRELATION (Among Trees) 57 FIGURE IV-5 Cross-Correlation Coefficients Among White Oak Trees on Contrasting Soil Textures LOOO- .900- .800 - .700 - .600- .500- .400- .300' .200- NE SW II Illllllll II IIII II I l2 4 9 ID I: I4 I5 :5 :7 l8 Iszomzzzsmzszszrzezss'osnszisu STAND NUMBER FINE TEXTURE ---- COARSE TEXTURE 58 The percentages of sand, silt, clay, and very fine clay for three levels in the.soil profile at each site (Appendix II—B) provided the independent variables for the STEPR routine.- The percentage of variance maintained by the group at each woodlot represented the dependent variable in each equation; as previously discussed, Fritts (1963, 1965a), Estes (1970) and others have demonstrated this statistics' sensitivity to growing conditions. Initially the STEPR program included only sites from Valparaiso westward (stations 5 through 10) in order to minimize the effects of the suspected regional climatic gradient. Then the program was re—run to include all woodlots across the study area (excluding the La Porte sites) as a precaution to see whether the results would differ substan— tially from the first run. In both runs the only statis- tically significant soil variable entered was the percentage of very fine clay at a depth of 50 inches. In the firsp run (Appendix II-D) the percentage of very fine clay at a depth of 50 inches reduced the total sum of squares by 33% with a correlation coefficient of .58; the same variable in the second run (Appendix II-E) reduced the total sum of squares by 35%.with a .59 correlation coefficient. The statistically significant (.05 level) positive relationship exhibited in both cases indicates that as the amount of very fine clay in the subsoil increases the percentage of the variance shared by the group also increases. The application of these 59 findings in a simple regression analysis (Figure IV—6) further suggests a highly significant positive relationship between very fine clay in the subsoil and tree response. Discussion Findings in the preceding analyses of soil textural variation and tree response suggest increasingly stressful growing conditions with increases in the amount of very fine clay in the subsoil. Since a large part of the water in the soil is held as a film on the surface of clay particles, the amount of clay in the soil has an influence on the total water holding capacity of the soil (Spurr, 1964, p. 285). However, the total water content of soils is not normally available to plants. Franzmeier §E_§i° (1960) proposed that the tensions at which soil moisture is readily available to plants is between .06 and 6.0 atmospheres. Based upon this finding, they proposed that loamy sands, sandy loams, and loams usually exceed clay loams and clays in readily avail— able water capacity (RAWC). The implication that moisture stress is more extreme on soils with higher clay contents supports the findings of the current research. In addition, the current results parallel those of Dyksterhuis (1948), Kucera (1957), and Elton (1970a). In the Western Cross Timbers region of Texas, Dyksterhuis found that vegetation patterns were controlled largely by soil— moisture characteristics. Upland stands of post oak I u n I 1 a u . shv ... ..Iu 15' awn DIV 0.. .A6 52 u l A Ju.e~44vvsq‘ v no .uz(otod‘) PERCENT VARIANCE (GROUPS) 66.3 - 60.6 ' 55.0 '- 49} - 43.7 ' 32.4 - 26.7 " 2|.l ‘ l5.4 ’ 60 FIGURE IV-6 Regression of Percentage Variance Retained by Groups Against Percentage of Very Fine Clay in the Soil at 0 Depth of Fifty Inches . O ‘ o O r=0.63 Sig. of F: (0.0005 0 0'5 4'5 8'.4 I23 use 26.: 24.0 27's 3i.8 35'] 38.6 PERCENT VERY FINE CLAY 61 (Quercus stellata) and blackjack oak (Quercus marilandica) were restricted to a belt of coarse-textured soils derived from sandstone where moisture stress is moderated, but on adjacent fine-textured soils to the east and west where moisture was less readily available prairie species per- sisted. Kucera, working in the southwestern Missouri Ozarks, concluded that edaphic factors were controlling the distribu— tion of prairie and forest vegetation types. Prairie species were restricted to finer-textured soils where drought stress was apparently more acute; and forest species, among them Quercus alba, were prominent on the adjacent coarse—textured chert soils. Elton, after an extensive study of forest and soil patterns along the Valparaiso Moraine in northwestern Indiana, derived negative correlations between the occurrence of mesophytic species and the percentages of silt and clay in the subsoil; conversely, the more xeric oak and hickory species correlated positively with the smaller soil fractions. Elton suggested that the higher [total] clay content of soils west of Valparaiso with their suspected smaller readily available moisture capacities favor more xeric forests of oak and hickory while discouraging the successful competition of more mesic species such as beech and sugar maple. Results of the INDXA and STEPR programs in the present research project appear to confirm Elton's suggestion on the importance of soil clay to plant response in northwestern Indiana, but further indicate that within the total clay fraction, the very fine clay component is probably pre-eminent. 62 Although it was beyond the sc0pe of this project to make a detailed listing of plant species present in the woodlots under study, some qualitative accounts of the dominant tree species were recorded. Based upon these observ— ations, it appears that there is an apparent shift from mesic to xeric oak species across the research area. Generally, red oak (Quercus rubra) tended to be a canOpy dominant (frequently with other species such as beech and sugar maple) on mesic sites in the eastern part of the area, white oak (Quercus alba) was less conspicuous except on the drier sites; black oak (Quercus velutina) was observed typically on sandier, very droughty sites. Near Valpariso and westward, white oak appeared to be the dominant canopy species, but often was accompanied by black oak and burr oak (Quercus macrocarpa); red oak was increasingly found where site qualities, such as soils and tOpography, provided moister growing conditions. Beyond Joliet, Illinois, approximately thirty miles west of the study area, the author noted that burr oak appeared to be the predominant forest species, followed by white oak and black oak. Burr oak is usually regarded as being a more drought tolerant species than either white oak or red oak (Fowells, 1965, p. 564). “Elton's (1970a, p. 38) frequency distributions of tree species across northwestern Indiana indicate a similar distribution of oak species. It is interesting to note, however, that in the present study and in Elton's (1970a) the area of most frequent 63 occurrence of white oak (approximately the area between Valparaiso, Indiana, and Park Forest, Illinois) may not coincide with the part of the study area where white oak appears to achieve its highest growth rates. Figure IV-7 represents the average ring-widths of all tree cores from each forested stand (excluding the La Porte stands) across the study area. The trend line on coarse—textured soils fluctuates greatly and is generally inconclusive; but the trend line for finer-textured soils is somewhat more consis— tent, suggesting lower growth rates at the two western-most stations, Lowell and Park Forest (stands 28-34). Conclusions based on these data are highly tentative because of the erratic growth rates on coarser soils and the small sample size representing fine-textured sites, but it appears that white oak may assume forest dominance on the droughtier, finer-textured soils (which predominate toward the west) where cOmpetition from more mesic species is less severe. Ring- width is usually inversely related to environmental stress (McGinnies, 1963); thus the apparent westward decline in average ring-widths, at least on finer-textured soils, could indicate more stressful growing conditions presumably brought about by climatic limitation. 'waever, if climate becomes ‘more limiting in the western part of the study area, in the small sample presented here the decrease in ring-widths first appears at the Lowell sites (#28 and #30) well west of the general terminus of the meSOphytic forest type. 64 mmDFxmb wwmdoo IIII memeL. sz zmmxaz oath en nm~nBona~o-wo~n~vwm-~$822222! : o. a v ~_ .. . . . .. .. ......... .- 3m m2 8.2on :8 8:82:60 co «3:. ..oo 22; s 2:33-85 52,. NI>~ mmDoE .60.. 6... tom; Icn ._ Ice.— nor... too; IS... too.— tom; Ioo.~ Io_.~ Io~.~ Iand (WI) NIOIM 9Nl8 NVBN 65 One puzzling feature of Figure IV—7 is the difference in ring-widths between fine- and coarse-textured soils; in most cases the mean ring-widths on fine—textured sites are significantly larger than those from coarse-textured sites. At Lowell, however, the larger value on the coarse—textured site (#29) compared to sites #28 and #30 was not statistically significant. Evidence has pointed toward more stressful growing conditions on finer-textured soils, regardless of location in the study area, when compared to conditions on coarseftextured soils; normally, on more stressful sites growth increments are smaller. However, this figure indicates that in the eastern part of the study area white oak achieves better growth on the finer soils. While the evidence is inconclusive, some speculation can be made concerning reasons for this apparent contradiction. First, these growth differ- ences may be more apparent than real, the result of too few data. To accurately establish growth trends many more data would be required, especially on the coarse—textured soils where variation seems to be larger. Second, if stand densi- ties should prove to be higher on the coarse-textured sites where stress is supposedly less pronounced, competition for available moisture, nutrients, and sunlight possibly would be greater during the infrequent periods of high moisture stress. Thus, by this line of speculation, growth rates ‘might be larger on fine-textured sites where competition is less. A I E.’ fl" 66 Third, there is some evidence that differential nutri- ent supplies among soils may be reflected in different growth rates in white oak. Usually a lack of nutrients does not preclude white oak survival, except on the poorest of soils (Fowells, 1965, p. 632). McVickar (1949) observed that white oak in Illinois obtained sufficient nutrients for adequate leaf growth on poorer soils low in replaceable bases, but on the richer soils, significantly higher nutrient contents were contained in the leaves. Arend and Julander (1948) found that oak growth, including white oak, in the Ozarks was higher on soils derived from limestone than shale or sandstone. Einspahr and McComb (1951) in northeastern Iowa recorded generally higher site indices for white oak growing on finer-textured soils such as silty clays and silt loams in comparison to site indices from coarser soils such as sandy loams, loamy sands, and sands. Since the nutrient status of soils is usually related to the amount (and kind) of soil colloids (Donahue et_§1., 1971, p. 53), and since the coarser soils in the study area are prObably more leached of exchangeable bases than the finer soils (Millar eg_§l., 1958, p. 248), the possibility exists that higher nutrient supplies on finer soils could result in higher growth incre- ments of white oak. Whether or not the transition of oak species across the study area is controlled entirely by edaphic conditions is not clear. The transition from red oak to white oak near 67 Valpariso seems to be strongly related to soils, but the transition farther west from white oak to burr oak could be the result of a climatic gradient. Data gathered in this project are insufficient to answer this question, but addi— tional soil samples and tree cores west of the present study area might offer a solution: if soil textures were similar to those in the western part of the current study area and tree sensitivities were higher, a climatic influence could probably be inferred. Summary Findings of the current research indicate that in northwestern Indiana on well-drained sites growing conditions are more stressful on the finer-textured soils than on the coarser soils. In ecotonal areas, such as northwestern Indiana (Braun, 1950, p. 322), site characteristics are very important in determining what types of plants will occur at any particular location. 'Thus, it appears quite possible that the higher amounts of very fine clay in the finer— textured soils could reduce the readily available moisture capacity sufficiently to exclude more mesic vegetation types, thereby exerting an important control over phytogeographical patterns in northwestern Indiana. [)1 r1 CHAPTER V REGIONAL CLIMATE AND THE TREE-RING RECORD Cross—Dating With Negative Mean Sensitivity Values In order to help determine whether or not sequences of wide and narrow rings occur in the same years among trees from different stands in northwestern Indiana, i.e., whether they display "cross—dating,‘ computer-derived nega- tive mean sensitivity values were plotted for the period 1890-1971. To recall, mean sensitivity is the relative first difference between any pair of adjacent tree-rings; and a negative value between two rings indicates a decrease in growth in the outermost of the two adjacent rings, usually because climate was more limiting than in the previ— ous year. Thus, by plotting negative mean sensitivity values of stand chronologies across the study area, it was possible to determine whether woodlots were responding randomly to characteristics of individual sites,-or whether these woodlots were reacting to common climatic stresses and would, therefore, display cross-dating (Fritts, 1969). The plots from selected sites in Figure V-l for white oak indicate that not only does valid cross-dating exist 68 69 05-0— 00..— OJO. 00.0. 0n_0_ 0mm. Oua— 81. .91 mm. . . - ...I. _._ it. _ L .. _ . .Li Z I. L . t .L - .m. . .L ._. _IP _ _ 11.». _ . 7: t. .Z. ip ..F .L _ mml . rt . :_i. E: _ . if _ LI : _ i . _ L _Ir._ _. pt : mmr ,F.. T... f. . _._ F rt; _ lulu L L: ._ _ _. L . emf. » C . I . . .e- C ____-_I _ ell L _. LT. L: _. wmr e. __ . L . r. .I _.. .2. i. . _I t t. L .r ..L .L_ : om. _ a . I.L E: t . ... b T _ _.. L ._ _ _ _— _. . : eiir .. .r _ _Ilr-...F.P L _. _._..Li #0 _. .. hr __— IL »_ . Ip». FLPL p—I _ _r —F p L _ ..h b p —» I.»»LLL ——P o. . . - - . t l . . Q FII » _ p t _ p p IF. L,F tilt? ~ 0 » p p k .P I _ . . L _ — p . p I p E p — — H . w — p p I I I ii — — L »_ I — p _ W W p _ E H — Pb b» I L IF — _ rL e: _. _L _+ t._ _ P_ _._ _.. e_ b__ __ _.___ __ __ .— NF p»- _ b . —_- bb » .L _ — .p ..p b— .ph— _— p—.»—.— fr —— F—— . sum... 2.22.. 5333532 5 moot. ..oo 223 Co 355 62023 Eat “9.2-59 . «33> 33:28 :32 326002 63.3012368 T) wxboi . on? I 30. . oao . 8.0- - and. - cos I 00.0. I n~0a I 00.0 I 000. I omo. I 00.0 I 00 0- I nwd- I 00.0 - one- - 3o. - So I 8.0- I “NO. I 8.0 I 000- I nwd- I 00.0 I 00.0- I nNOI I 00.0 - coo. . one. - 88 I 000- I ON 0- I 00.0 I 00.0- I 0ND. I 000 I000. .. o~.0. I 000 I 0nd I I 90.0. I 00.0 »h_>_tmzwm z 2.2 82 8.2 9.8. 8.9 82 ca. o8. .8. . _ _ -8 o. _ -39 onrl b>>.II— FI» I Lpprb I» h IpIIFp — I>I_>¥ I— —_b I PI I_ I80 .000. ...: .t: ._ ._ r: - _..: r _;:: L r. __ L .: “MM“. - 8 .o- - 39 -80. _ -39 p . .95 I 00.? — I n~ 0. SF t_._.I.I_»I I __ _F __I.._ h __II__ _____ .I __ Ioo.o .00.? E. It __-IIr I_I I_ __ _I __c ..I _. . .I_ cF __I .-. Ir_ _I_ mew- mmmxaz mtm >b.>_:mzum 21m! 229: 5233532 5 $8.. :8 :85 do $55 882% so: 8.87.3. V 32.5 $2556 :8: «2382 82.812358 ~I> wane-u 72 With the exception of site #28 (Lowell) precipitation and tree growth were negativelyrelated. Mean maximum April—May temperatures of the current season also were negatively related to growth at two La Porte sites. Mean maximum June temperature of the current season was the most frequently entered variable, appearing in eight locations from Valpariso eastward on the coarser— and finer- textured sites. In each case mean maximum June temperature and tree growth were negatively related. On the other hand, total June precipitation of the current year exhibited posi— tive correlations with ring-width at five western locations. Climatic variables for months preceding current growth showed some‘importance at a few western sites. The preced- ing season’s total June—July—August precipitation was posi— tively associated with growth at three western sites, while Octoberemarch precipitation was negatively related at three western sites. In overview, tree response in northwestern Indiana seems to be most closely related to'cIimatic conditions of the_ current spring and early summer; June variables were especially important. These results compare favorably to a recent dendroclimatological analysis in this region by Ashby and Fritts (1972). Although the evidence is not decisive, indications are that response to moisture variables may be more direct in the western part of the study area, whereas temperature variables are more prominent in the east. 73 Discussion Physiological Implications At first glance the negative relationship between tree growth and current season April—May rainfall is surprising. But Fritts (1960) found white oak radial growth to be very sensitive to soil moisture conditions of April and May; inhibited growth accompanied arrival at field capacity, possibly because of poorer aeration and lower soil tempera- tures for root development. Similar reasoning may account for the negative correlations of October—March precipitation. Originally October-March precipitation was included in the analyses to determine if winter soil moisture storage, particularly in the eastern part of the region where winter snowfall is heavier (Changnon, 1968), might be important in understanding the forest transition across northwestern Indiana. However, the only influences indicated were nega- tive, and these occurred at western sites, probably because of the high moisture holding capacity of the fine-textured soils at the three sites where this variable appears (Kramer and Kozlowski, 1960, p. 88). Frequently in white oak (Quercus alba), June represents the critical point between earlywood and latewood formation (Fritts, 1958). Wetter and cooIer Junes would tend to prolong production of the wider earlywood cells thereby creating wider total growth rings. The reverse would be true in Junes with high evapotranspiration rates and lower moisture availability. 74 Rdbbins (1921), Diller (1935), Freisner (1943), and Estes (1970) detected close relationships between total annual diameter growth and moisture conditions of June. The presence of the preceding June-July—August total rainfall as a significant variable apparently demonstrates the "lag effect" described by Diller (1935), Fritts (1958), and Zahner and Donnelly (1967). If conditions are favorable late in the growing season when vegetation growth is declin- ing, trees may manufacture and store more than normal amounts of food materials for use the next spring. If stored materials are less available to the tree in spring, the potential for growth is reduced (Kramer and Kozlowski, 1960, Ch. IV). Thus, late-season Conditions often influence the size of the next year's tree-ring (Hanson, 1941: Gagnon, 1961). Ecotonal Implications The apparent trend to different types of significant weather variables across the study area is difficult to assess in terms of the forest gradient. Frequently, different combi— nations of significant variables appear on different sites around the same weather station (Appendix IV-A); this pattern may mean that soils, tOpography, and subsurface drainage partially decide which weather variables most highly corre— late with tree response at a particular site. Thus, the higher multiple correlation coefficients and percentages of 75 explained variability westward, and the apparent shift from temperature to precipitatiOn variables across northwestern Indiana, could be the result of regional edaphic contrasts. If the apparent shift in climatic controls is a reality—- and the data are not conclusive—-at this point the signifi— cance of these findings to the forest transition is unclear. Interpretation of the Index Program Results In the following analyses, a variety of figures have been derived which depict the trends of INDXA parameters across the study area on similarly textured soils. Rather than presenting data for individual woodlots as in previous diagrams, each point on a figure represents the average parameter value for all sites having approximately similar soil textures at that station. The purpose of this procedure was to reduce the wide variability often displayed among sites at most stations, in order to render general trends possibly related to climate more easily discernible. Care must be exercised in interpreting these charts because of different sample sizes represented by points and probable undetected disturbances at some sites. The Regional Climatic Gradient Mean ring-widths on finer—textured soils decline notice— ably at the westerndmost sites of Lowell and Park Forest, 76 but on coarse-textured soils any decline is very slight (Figures V-3, V—4). Westward, mean sensitivities (Figures V-S, V-6) and percentages of variance retained by groups (Figures V-7, V-8) apparently decline on finer-textured soils and rise on the coarser soils. Cross-correlation coefficients may rise toward the west on coarser soils, but the trend on finer-textured sites is indefinite (Figures V-9, V-lO). In an attempt to clarify the inconclusive, sometimes contradictory, trends in the figures described above, simple correlation techniques regressed these same chronology para— meters against the distance westward of individual sites from an arbitrarily drawn Iine east of the study area. Significant relationships between tree—ring parameters and increasing distance westward presumably would manifest increasing climatic stress. Results of these regression analyses do not always suggest a close relationship between tree response and westward position (Table V-l). The only significant trend appeared with mean ring-widths on fine— textured soils, but the sample size of nine data points is too small to be conclusive without additional supporting evidence. The Lake Michigan Mesoscale Climatic Gradient A comparison of chronology parameters between coarse- textured sites from Michigan City (#9 and #11) and Hobart MEAN RING-WIDTH (mm) 3.00 - 2.00- LOC- 77 means v-3 Mean Ring-Widths Among Stands of White Oak Trees on Fine- Textured“ Soils at Selected Stations NE SW I I I Michigan City Valparalso Hobart STATION *6 LESS THAN 50% SAND AT DEPTH 0F 50in. I Love" I Park Forest 78 :o.°5 tone: 5.0m mo 7:.de #4 oz mane; o_.o ONO omd AlMlllSNBS NVBN - Iii \AAU Que-s- nvb th av ..Vpsnv~\-U\I rink {'ilh‘ II I . 81 .33... tom .500 m0 Ihamo k4 02 mmaoi om 0v 00 cm 00. (SanUEJ) BONVIUVA 1N3083d 82 zone... .58 to fame S ozam ..\oon 23:. one: ... 22:; :8... ass...) 5.2.; :8 .5255 3.2.3 28 5.8 Fm uz 2385 3823 E m__om...u83xo._.I$.Eoo go 32.— goo 22; B 8:95 B 3508: occur—5 B 0323.8 3223 OI) mung“. 0m 0m 00_ (sanoue) BONVIUVA 1N 3383c! 83 5 .. IIICBFI. FIE.L§N?.' atom {on .500 m0 Ihnmo k< oz wmnwi 0m 9.. 00 om 0? (ma MOW) IIouvuIIaoa-ssouo 84 .cuon .....0 theme P< oz< o_-> mass... (“”1 WWW) NOIIVIBUUOO-SSOUO 85 TABLE V-l. SIMPLE REGRESSIONS OF TREE-RING PARAMETERS AGAINST DISTANCE WESTWARD FROM THE INDIANA—OHIO STATE LINE Correlation Parameter Soil Texture Coefficient Mean ring—width Coarse —.29 Mean ring—width Fine —.73* Mean sensitivity Coarse .29 Mean sensitivity Fine .47 Per cent variance—group Coarse .15 Per cent variance—group Fine —.16 Cross-correlation among trees Coarse .11 Cross-correlation among trees Fine —.29 * Value significant at .01 level. ‘15. {ff-Em?! I‘ F,” 86 (#26) shows similar mean ring-widths between stations, but percentages of variance (group) and cross-correlations among trees at HObart range from about 3-8% higher than at the more easterly sites (Appendix III-A). On fine-textured soils, the percentage of variance (group) at Hobart (#27) is 19% higher than at Michigan City (#10); mean ring—widths are higher at Hobart. There are also differences in chronol- ogy parameters between Michigan City and a comparable site to the south. If only the most sensitive coarse-textured sites at Michigan City (#11) and Wanatah (#15) are compared, all chronology parameters (except mean ring—widths) are higher at Wanatah. Chronology parameters at Hobart (site #26) and Wheatfield are much alike. Comparative Sensitivities of White and Black Oak Appendix III-C represents the chronology parameters for white oak and black oak; each pair of samples was taken from the same forested stand. In most cases the percentage variance in groups and the cross-correlations among trees are from about 8-10% higher in black oak. The excessively well-drained site at Ogden Dunes (#25), where the percentage variances retained by the group were 41% and 30% for black and white oak, respectively, is illustrative. w V‘s-77.”; r". w ‘ifhlgh 4.; ' ‘ W n _. 87 Discussion Climate and the Forest Ecotone Considered collectively, the preceding results give little, if any, conclusive evidence for a pronounced climatic gradient across the region. Climatic gradients of a magni— tude to cause an abrupt transition of major forest types probably would have left a noticeable impression in the tree- ring record. The variabiIity of chronology parameters among sites and the inconsistency of trend lines suggests other factors are more limiting to plant response than climate. From the strong relationship between soil texture and tree response demonstrated in the previous chapter, the predom- inant control of the forest gradient in northwestern Indiana appears to be a function of soil texture. However, the importance of soil texture does not mean that climate lacks phytogeographical significance in the region. A characteristic of phytogeographic tension zones is the importance of site characteristics to local plant distributions (Braun, 1960, p. 322). In the study area, the researcher observed that the beechemaple forest was restricted to coarser-textured soils, often imperfectly drained, where ‘moisture stress is apparently moderated. On finer-textured soils sampled in this project‘within the meSOphytic zone, beech and sugar maple were excluded from the forest canopy. Beech has been found to be sensitive to moisture stress (Spaulding, 1946); thus, the absence of beech and sugar maple 88 finer-textured sites suggests moisture stresses beyond on If climate were not marginal the tolerances of the species. survival of mesophytic species in the region, it seems for likely that these species would occupy a greater variety of sites and soils. Beech and sugar maple usually achieve their best development on mesic sites of intermediate textures, but both species have shown a wide tolerance for many soil textures (Crankshaw, 1965). Th? Lake Michigan Mesoscale Cl. 1matic Gradient Leighly (1941), Visher (1944), Changnon (1968) and Harman (1970) have discussed a likely moderating influence of Lake Michigan at locations near the eastern and south- eastern shore of the lake (Figure 1-1. p- 2). WhiCh C0111d Influence plant distributions. Suitable stands, particularly near the lake, were difficult to locate; many sites were either excessively well drained (dunes) or poorly drained. 1" . . . rot“ the small number of Sites available, only tentative s . _ “99 estions are pOSSible . Higher sensitivities at the Hobart sites in relation t 0 those at Michigan City may indicate slight climatic dif- E at elaces east-west between the two stations, although the di f:Eerence in sensitivities on coarse-textured Sites is less or‘lcaunced than on finer 50113. In addition, forest compo- S ‘ . ltlon may manifest subtle climatic changes. At Michigan city ' ' . the forest canopies on the two coarse-textured Sites i“?! 89 were mostly white oak with some black oak, over an under- story of Cornu§ florida (flowering dogwood), Corylus americana (American hazelnut), and Hamamelis virginiana (witch hazel). Black oak with smaller numbers of white oak prevailed at Hobart, with an open understory composed mostly of grasses and some Vaccinium species. The fine— textured site at Michigan City contained white oak, red oak (Quercus rubra), and shagbark hickory (Carya ovata), whereas warn-WWI"? the site at HObart was almost entirely white oak; Crataegus species dominated the understory at both fine-textured sites. Thus, tree-ring parameters and species composition seem to indicate that the Hobart sites are somewhat less mesic. The evidence for a climatic gradient southward from Lake.Michigan is unclear, particularly because of the varied responses at the three Wanatah sites. If the most sensitive site (#15) at Wanatah can be considered representative for the station, this higher sensitivity to the south would be anticipated if climatic conditions are moderated to the lee of Lake Michigan. Also, the negligible differences in sensitivity between Hobart and the most sensitive Wheatfield site would be expected if, as discussed above, climatic modification by the lake is less in Lake County than La Porte County. Again, the data are too few to be conclusive. Black Oak and White Oak In Future Research In most cases, the parameter values for black oak are higher than for white oak. Black oak is noted for its ability 90 to inhabit poorer, droughtier sites (Fowells, 1965, p. 559); this is dramatically evidenced by its greater responsiveness on the sand dunes near Lake Michigan, where growing condi- tions are stressful. In future tree-ring research, black oak, when available, may be a more useful species than white oak. i ...I Summary t The investigation of tree-response and climatic patterns in northwestern Indiana consisted of three parts: cross- dating with negative mean sensitivity values, correlations of tree-ring indices and climatic data, and analyses of the Index Program results. Plots of computer—derived negative mean sensitivity values indicated that valid cross—dating exists not only among well—drained sites at each station, but also among sta— tions across the region. This fact suggests that forest stands across the region have displayed some similarity in their responses to common periods of climatic stress. The correlation analyses raised the possibility of. divergent climatic controls across the region, but the sig— nificance of this suggestion for plant distributions is unclear. An analysis of tree-ring parameters from the Index Program provided no apparent evidence of more stressful climatic conditions in the western part of the study area. Yet, the restriction of certain mes0phytic species, notably 91 American beech (Fagus grandifolia), to favored sites where moisture stress is probably reduced, suggests that climate may be marginal for less drought—tolerant species across much of northwestern Indiana. A tentative conclusion was that the immediate control of the forest transition from meSOphytic to more xerophytic species in the study area is ;_d predominantly a function of soil texture. Based upon limited data, there is some evidence that tree-ring sensitivities are lower near the southeastern shore me‘fi'fi-rmw In,“ _of Lake Michigan than at more westerly or southerly loca- tions. These lower sensitiVities may reflect a leeward mesoscale climatic modification by Lake Michigan. Black oak appears to be a more sensitive indicator of climatic variation than white oak. In future tree-ring studies, when available, black oak may be preferable to white oak. CHAPTER VI THE LA PORTE PRECIPITATION ANOMALY Review of the Literature One objective of this project was to search for tree— ring evidence of an anomalous climatic pattern in the vicinity of La Porte, Indiana, described by Stout (1962) and Changnon (1968b, 1970). The published climatic record at La Porte, which stands in contrast to records at other stations in northwestern Indiana, has been intensely analyzed; yet, interested scholars still do not agree upon the validity, causes, or extent of the so—called "La Porte precipitation anomaly." Part of the current research was designed to gather data which might clarify some of the uncertainty sur- rounding the problem. lndications of the anomaly appeared in several earlier studies (Visher, 1935, 1944); and an article by Stout (1962) prOposed that temporal changes in the precipitation and cloud cover record at La Porte agreed with temporal changes in iron and steel production from the Chicago-Gary indus- trial complex. The agreement between industrial production and climatic change, and the location of La Porte approxi- mately thirty miles downwind from the iron and steel 92 93 production center, suggested a relationship between the two phenomena. Changnon(l968b), based upon a limited number of obser- vation stations, mapped a northeast-southwest trending, elliptical ”island" of abnormally high rainfall centered on La Porte. Weather records from 1898—1968 showed that annual warm season precipitation between 1929 and 1963 at La Porte were 30—40% higher than at surrounding stations in northern Indiana; but prior to and following the period no consistent differences were recorded. For example, the average annual precipitation at La Porte from 1929-63 was over 11 inches higher than the 1964—68 years; furthermore while La Porte was experiencing apparent increases in yearly values from 1930-39, Valparaiso (.20 miles upwind of La Porte) and South Bend (24 miles downwind) were showing general decreases. From 1930-39, La Porte averaged 46.3 inches per annum, Whe-t‘eas 38.4 inches were recorded at Valparaiso and South Bend respectively; from 1940-49, La Porte averated 55.8 incflies per annum, 43% larger than Valpariso and 61% larger than South Bend (Figure VI-l) . The next ten—year period produced a substantial decline in La Porte yearly precipi— tation totals; warm season precipitation, annual number of thunderstorm days, and annual number of hail days exhibited Simj—ILar temporal distributions. After considerable effort toward the correlation of year“to—year weather variations with the temporal distribu- to 91-01-13 of steel production in the Chicago area, Changnon 94 FIGURE VI-l Mean June-August Precipitation Totals l940-I949 f3»: ......ti..r......-£=F . .c I5.0 ‘- l0.0 — 5.0 ._ VALPARAISO LAPORTE SOUTH BEND HOBART CLIMATOLOGICAL DATA so” RC5 95 (1968b) concluded that additions of condensation and freezing nuclei, water vapor, and heat to the atmosphere were the primary causes of the La Porte rainfall anomaly. Holzman and Thom (1970) , however, challenged the reality of the anomaly; subjecting the La Porte weather record to statisti— cal analysis, they concluded that changes in observers and recording procedures produced inaccuracies in the weather data. Ogden (1969), from rainfall studies near an Australian mu“ din-11.1.." ' ‘ steelworks, expressed doubt that the unusual La Porte weather record could have resulted from industrial causes. And, Elton (1970a) suggested that other factors, including synOp— tic conditions and lake breeze convergence, also may have been causally related to the La Porte anomaly. After an examination of stream—flow data for the upper Kankakee River watershed, Hidore (1971) found that the flows of these streams increased substantially, especially during the warm season, and the timing of the runoff increase coin- cided with the prOposed La Porte anomaly. Thus, Hidore's resl-‘llts supported the validity of the precipitation record at La Porte. But the conclusions of another hydrolOgic Study conducted by Holzman (1971) disagreed with those of FidOre (1970). ~ I-Iarm'an and Elton (1971) found that tree-ring variation in a stand of red oak trees near La Porte revealed patterns 0f cI‘oss-dating and climatic correlation which might be e“pected if the precipitation anomaly were a reality. 96 Lindsey (1969, p. 511) in support of the anomaly, reported denser shrub—layer tree reproduction in the mesic forests around La Porte than in other forests in northwestern Indiana. But; Ashby and Fritts (1972) could find no evidence in white oak tree—ring records to support or refute the existence of the anomaly. However, they did suggest that some factor in the La Porte area became increasingly more limiting to tree growth than climate during the 1940-50 period, and caused a gradual reduction of growth. Toxic effects from severe air pollution correlated with high levels of smoke-haze in Chicago during the decade of the 1940's was suggested as the Cause of growth reduction. The La Porte rainfall anomaly is not only an interesting PrOblem, but it is an important problem, for if the anomaly is real, it represents an interaction between two major Problem areas of meteorology: weather modification and amTKDsPheric pollution. And if the anomaly is fictional, Serious questions about the validity and usefulness of long- term climatological records may be in order (Changnon, W C o O O ‘ \aggrelation of Climatic Data wee-Ring Indices ' The stepwise multiple regression analysis procedure (STEPR) described in previous chapters was applied to climatic 97 data and tree—ring indices for four forest stands at La Porte and one control stand at South Bend for the period 1910—69. For each stand, the climatic and tree-ring record was divided into three ZO-year intervals, the purpose being to determine whether patterns of change in the statistically significant weather variables were present which might indicate temporal climatic changes. The statistically significant variables entered into the regression equations by STEPR are presented in Appendix IV—C. At each La Porte stand, no variable was statistically sig— nificant for all three intervals at any one woodlot. At site #6. the most sensitive site at La Porte, mean maximum June ta'tlperature did appear in the first and third intervals, but Other variables were entered in the second interval. Interestingly, at site #6 during the second interval (which coincides with the height of the proposed anomaly) multiple Corr elation coefficients and the amount of explained varia- bility (cumulative sum of squares reduced by significant variables) are much higher than in the other two intervals. In each of the other stands at La Porte, except #8, statis— tical patterns are similar, although less pronounced, to thése of site #6. At site #‘i different significant variables were entered in each of the first two intervals, but none were entered for the third interval. As at Site #6, mean maximum June t .. gaperature of the current season appears in the first and 98 third intervals, but not in the second; mean maximum April- May temperature of the current season was entered in the second and third intervals. Correlations for the South Bend site indicated some changes in important variables through time, but temperature- related variables generally prevailed throughout the analysis period. An exception was current season April-May precipi- tation which was prominent in the second and third intervals. The explained variability and'lthe multiple regression coef- ficients were in most cases higher in the second and third intervals at South Bend than in the La Porte stands. The 1930-49 interval at South Bend produced the largest number of Significant variables (5) , the highest explained vari- ability (80%). and the highest correlation coefficient (87%) 0f the three intervals. Am&1Lses of Tree-Ring Chronologies Statistical parameters for the tree—ring chronologies of the four La Porte stands are given in Appendix III—D. Each of the sites has been divided into four 20-year inter— Vals from 1890-1969, as have control stands at South Bend. Michigan City, Wanatah, Valparaiso, and Park Eorest. Three of the La Porte sites (#5, #6, and #8) display mean ring—width characteristics which are typical of distl-‘l.:r:bed woodlots: sites #5 and #6 show persistent increases 1 ‘ . u ‘mean ring-widths, and site #8 changes relatively little 99 through the four intervals. Site #7 is more typical in that ring—widths decline with increasing age. Most of the control sites from other stations show generally declining mean ring— widths as the trees grow older. Anotable feature of all sites across the study area (except at sites #5, #6, and #18) is the smaller mean ring—width value in the 1930-49 interval when compared to mean ring-widths in adjacent intervals. A consideration of control site data in most instances reveals a steady decline of the group variances, percentages of variance retained by groups, cross—correlation coefficients among trees, and mean sensitivities as stand age increases, with the largest decline in parameter values usually occur- ring in the 1950-69 interval. The four La Porte sites follow comparable temporal chronology changes, with no consistent aberrations appearing at all four sites. Discussion In the current discussion it is pertinent to note that chronology parameters do not appear to remain constant th-":’C>ugh time. Lodewick (U30) and Senter (1938) reported decreasing intercorrelation as stands of southern pines Abecame older, and Harman and Elton (1971) , observing decreased J‘ntezlccorrelation in a stand of red oak near La Porte. have prc"’ided several possible explanations for decreasing shared 8 - . . . . . . . ens :LtiVity among trees. First, phySiological changes within t . . . tees of increasing age may produce varying senSitiVity to 100 external environmental variation. Went (1942), and Gunckel §£_§1. (1949), and Robbins (1957) have documented the slowing- down of life processes in aging trees. Second, maturation of the forest stand and accompanying canOpy closure may have increasingly moderated the subcanOpy environment, buffering the trees from macroenvironmental stresses. Estes (1970) reported decreased sensitivity in stands of pine following canOpy closure. Third, early disturbances to the woodlot (grazing or frequent fires) may have brought stresses to the young stand. And, finally, the general environment may have ameliorated recently, resulting in increased independent variation among trees. In the present project, the regular decline of chronol- ogy parameters over the past eighty—one years from widely separated sites suggests that the most probable causes are aging processes and in some cases perhaps canOpy closure. Widespread climatic change across the region of a magnitude capable of substantially reducing tree sensitivities is not considered likely; and early disturbances to the woodlots under analysis is not indicated (with one possible exception to be described presently). The full significance of declin- ing responsiveness of trees in dendrochronological research nis difficult to assess. But in future studies where para- nneters from different forest stands are to be compared, as .in studying climatic or edaphic gradients, comparable stand Eages would seem to be desirable. For example, all things 101 being equal, sensitivities in an older forest stand probably would be lower than in a younger stand. If age differences were ignored, one might erroneously conclude that environ- mental conditions between the two stands had been dissimilar. In the present study, the oldest stand (La Porte #5) was also the least sensitive. The tendency for declining sensitivities with time makes interpretation of the current results difficult. Multiple correlations between tree-ring indices and climatic data at La Porte do not reveal a decline during the 1930-49 period which would be anticipated if substantial precipitation in- creases had occurred during that period. In fact, both multiple correlation coefficients and variability explained by statistically significant variables become larger in the 1930-49 interval at sites #5, #6, and #7, similar to responses at the South Bend site; only at site #4 is there a decrease in the second interval. And further, even though in numerous instances the significant variables change from one interval to the next, no particular pattern of change is evident. However, correlation coefficients were generally higher at the South Bend site, which cOuld be a reflection of more stressful growing conditions, especially in the 1930-49 interval. Chronology parameters for sites across northwestern Indiana reveal no patterns which might suggest higher rainfall at La Porte. In the La Porte chronologies, values generally 102 decrease after 1930, but the declines are similar to those occurring in control groups away from the La Porte area. If anomalous precipitation conditions are contained in the chronology parameters, they are obscured by general decreases in sensitivity which accompany aging of stands. These results do not necessarily exclude the possibility of an anomalous rainfall record at La Porte. It should be recalled that earlier findings in this project have indicated that moisture stress is usually lower on coarser—textured soils, like those at the La Porte sites. On these coarser soils, moisture is probably sufficient for tree growth most of the time, such that shared response among trees to climate is rather low, and individual tree response to environmental factors is relatively high. Thus, the addition of more mois- ture at these rather insensitive sites probably would alter the chronology parameters only slightly. The addition of more moisture might, however, promote larger growth-rings in trees. A comparison of mean ring— widths before and after 1930 for the La Porte sites and the control groups is presented in“Table VI—l. As with other analyses of tree response, the results are not well—defined. The South Bend and Wanatah stands decrease noticeably after 1930 as would be expected, but the La Porte values are mixed: stands #5 and #6 increased, #7 decreased greatly, and #8 decreased slightly. The reasons for the mixed response at La Porte are not entirely clear. 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Nm NN Ne mmo. Nmo. ma. NH. mm. om.N smog Nmao oN om. me 0N mm «No. Nmo. ma. NH. co. N¢.N ccmm m >uNo cmmwgoNz mm. NM Nm mN ONO. moo. ma. ma. Nm. «N.N camm heaoq m Nm. o¢ mm 0N Hmo. oNo. ma. «N. we. «N.N ccmm aemoa N cm. em mN mm mmo. mNo. «N. ma. me. Nm.N ucmm weaoa 9 ea. mm ON ON HNo. Nmo. ma. NH. Nn. om.N ucmm m wuuom ma o¢. mm mN Nm mNo. mmo. ma. ¢N. NN. NN.N ccmm q mm. oN NN ov Hmo. ONO. NN. NN. NN. mm.N ocmm .m ow. N¢ eN mm MNo. Nmo. oN. MN. Ne. oo.N ncmm N oe. mv «N on NNo. one. ma. ma. av. mo.N vcmm mecca N vcmm :uoom umoub Asowv A9». va va m cofiumfi>wo >ua>fiu coHumH nuoqz monocfl om .oz coflumum mcoad awumm mmmufi msouo mucmNum> mo unacCMum Iflmcmm Imuuou Imch "musuxma Afiom mufim umnummz :ofluma mocmNum> macho uouum cmmz Hmfluom cam: :wuuou Hmuoa wo ucmouwm nmmouo mumumamwmm wmoHocouflu <24HQZH zmmfimmxmamoz 2H X‘O mfiHm3 m0 wDZdBm mom AOhmHIOmmHV OOHmMm mUZ m0 mHmVA mmo. o¢ mm mm Hm. ¢H. om. mmumoo Ha mmo. mm Hm nw mm. ha. mm. mcwm OH mNo. aw 0N mm om. NH. vo. mammoo m muNo ammflnofiz Amv Aauwv Aewv va mmmne muN>Nu cofluma musuxma .oz coNumum mUGMNum> Hflnmm mmmue msouw mc05< Iflmcmm Iwuuou Aflom muflm unnummz macho. mocmwum> Hmuoe coaama cmmz amaumm Hawuu< mo ucmoumm Iwnuoo Immouo av. moo. Nm Hmo. mH. m¢. mo.N om mN. Nmo. HN one. oH. N¢. om.H oz oH mm. oNo. HN «No. «H. o¢. Nm.H om um. Hmo. Hm HNo. mH. m¢. ¢N.H o: «H amumcmz mmmHa. » Auv va muH>Hu :oHumH Aesv mmHummm muHm coHumum macam mo macaw ma 00cm Iflmcmm Imuuou nucwz , coHuwH Houum mucmwum> Iflum> ammz Hmwumm Imcflm Imuuou unmoumm muonw cmmz. Immouo mMBHm 20mm mmmamz€m mv. he vH NN HNo. woo. mH. vH. Ho. mo.H momHuommH NN. vq 0N mN oHo. Noo. ¢H. wH. HH.: mH.H mvauonH No. om m mo Nvo. hmo. HN. oH. Nm. vw.H mNmHIOHmH vo. Ne oH me nmo. moo. vN. HN. h¢. mo.H mnuaou mooHuommH mH zaumcmz HN. vm NN «H coo. Hvo. no. mo. He. Hm.H momHuommH mm. mN mH Hv oNo. ovo. mH. NN. om.n Nv.H mvanONmH co. co 0H om «No. mNo. oH. oN. oH.u Nm.H mNmHuOHmH no. mN mH Nm Nvo. «mo. HN. mH. mN. NH.N wch momHnommH oH >uHU :mchoH: mN. om vN oN boo. Neo. mo. mo. mN. NH.N momHuomoH Nm. no N NN NHo. mNo. NH. 0H. h¢.: mm.H m¢mHuonH av. 0N mN on hHo. omo. ¢H. 0H. No.: NH.N mNmHaonH mm. NN NN mm NNo. poo. mH. mH. Nw. NN.N maumou momHuommH m NN. 0v oN vN moo. oNo. mo. no. Nv. mo.H momHuommH mm. on HN oN oHo. ovo. HH. NH. NN.: No.H mcmHuonH oq. vc NN mN mHo. mNo. NH. oH. NN.: ov.N mNmHuonH 0N. mH Nm mN mNo. «mo. NN. HN. HN. mm.N wmumou momHnoomH N Hv. hm mH «N moo. nvo. oH. mo. 0N. cm.H momHuommH No. NN mH Nv mvo. moo. NN. mH. 0N. on.H mvanoNoH 05. mm oH on Hmo. mmo. 0N. wN. 0N. oo.H mNmHuonH mm. o 00 NN ono. NHN. «N. oN. mo. mm.H mmumou mooHuoomH o vH. ch mH m Noo. Hco. no. 00. ON. mv.H momHnommH mH. hm HN NH Noo. mmo. OH. NH. mm.n mN.H mvauonH mH. oh mH NH moo. Noo. NH. oH. NN. oN.H mNmHuonH mm. mm m HN mNo. vvo. 5H. NH. Nm. mH.H mmumou momHuoooH m muuom MA mN. mv 0N mN woo. mNo. NH. mo. NN. NN.H momHnommH vo. on oN mN oHo. Nvo. NH. vH. NH.u qv.H mcmHuonH mm. mv NH mm mHo. Nco. 0H. vH. mH. mm.H mNmHnonH mo. Nm m mc vNo. NNo. oN. mH. HN. vm.H wmumoo momHuommH N ocmm nusom mooue Heuwo Hewv Hwy Ax. w coHumH>mo qu>Hu :oHumH :uon unauxue voHuom .oz coHuMum mcoa< HHomm ammua maouo vocmHum> mo Uumvcmum nHmcwm umuuou nmch HHom mmouu wucmHum> uuHm coHuaH mocmHum> macho Houum cam: HmHumm cmmx mo umeHmcd umuuou HauOB mo unmoumm ummouu mumuvmmumm >UoHocou£U 2H mmBHm 02¢ mZOHHkBm 8903mm 5mm mQOHmmm MUZ m0 coHumoHMHuchH mmmMQ¢Z¢ UHHfiZHAU mom mmqdem<> QWBUMHmm .¢I>H XHDmemd 149 .Hw>mH mo. um ucmoHuHcoHu NHHmUHunHumuu .coHuMkuuou m>Hummsz .Hm>mH mo. um ucmuHchmHm hHHmuHumHumun .coHuMHouuou 0>HuHmom+ .ooumucu anmHum> ucmunHcmHm oz .C ”—1 mHmHuHsz me3Qmum H . .. m I H mv. mo. em. I + . _+ I NN NN. mm. mm. mI I Nm vv. NN. #o. I + + I HN ummNOh xumm mm. 0N. $0. I ... I. OM. vN. 0N. mc. I mN we. «N. mm. + + mN HHoon Hm. mm. mm. I NN Ne. NN. No. I 4 + «N uumnom N¢. NN. mo. _ + NN III III III _ .HN nHmeummzz III III III oN om. Nm. mo. I + NH mH. «H. HN. I mH III III III «NH omHmummHm> Nm. NH. NN. I I m III III III IN mN. vN. Nm. I . a o 0N. NH. mm. I I w m wuuom NH NN. NH. ac. I w I c III III III «N mm. NH. NN. + I I N NN. NN. we. I m I H Gama suaON 8.03 SS 33w 8 P V n. P V O 8 VP V V V P P V muHm coHumum 9.4 b Igun a n n n an d 3 Ho n_u d d n“ n n Au Pan n.m 0.47. d u .b ,I u .J .4 d can .4 1 6 .I u .4 3.. no.3. .... “I... .12.. if... mmwm. 8.5 .ld m n. 3 w W m .+nI W V a» W opnwn s 4““ m. m m n m. w M m N o A 1 A . J A . u a _ u - I cHomomu ucmuudu mchmuwum ucmuuzu mwsz> mHm I INHmc< conmwumwm ousumuwmama coHumuHQHumum ONmHIHmmHIIE/HHNHQZH Zfiemméamoz ZH mmBHm 024 mZOHBCBm 80mm AWZOmfim DZHQmummm Q24 HzmmmDU mxB “HOV mmqde m<> UHHH xHazmmm< 150 .Umumucm mHQmHHm> uCOUHMHcmHm OZNO NHm>mH Ho. pm uchHMHcmH m mmHanum> HHON OH I ON. NO. N I OO. OO. ONH. OOIOOOH OH I HO. ON. NNN. OOIONOH HH I NN. OO. OH + HO. ON. NNN. ONIOHOH O II II II II II OIOOIOOOH O + NO. NO. O I OO. ON. HOH. OOIONOH HH I NO. NN. ONO. ONIOHOH N O I NO. ON. ONN. OOIOOOH NH I NO. NO. N + OO. OO. OON. OOIONOH O I OO. ON. HNN. ONIOHOH O OH I OO. NN. N I NO. NN. ONH. OOIOOOH O I OO. OO. O I OO. ON. HNN. OOIONOH OH + NO. OH. HNN. ONIOHOH O muuom OH OH + NN. OO. HH I OO. NO. H I OO. ON. NNH. OOIOOOH HH + NO. OO. N + NO. ON. OH I ON. OO. H I NN. OO. NH I NO. ON. OON. OOIONOH OH + NO. OH. NOH. ONIOHOH N Ocmm nusom .oz cmNm N.m.Q How Umoscmm mmumdvm Hm>uwucH .oz coHumum IOHQOHHO> OOOOONOOO aoHuuomoum mo EEO OENB muHO coHuMHmuHoo m>HumHSESU mHmHuHsz mmmHIOHmH OOHmmm mmB mOm WBmOm dd Q24 szm EBDOm 20mm mWHMflHm¢> UHB¢2HAU QMBUmHmm BmZH404 mmUHQZH OZHmlmmmB M40 MBHEB m0 mZOHmmmmomm mamHBADZ.mmH3mmBm .UI>H XHflzmmmd HICHI 9N S TE Iv III/III; III}! III/III III/7W 31293102151515