71-18,269. U niversity M icrofilm s, A XEROX C om pany, A nn Arbor, M ichigan

Transcription

1 71-18,269 PARKER, George Ralph, THE STRUCTURE OF A SWAMP COMMUNITY IN NORTHERN MICHIGAN AND ITS REACTION TO PARTIAL DRAINAGE. Michigan State University, Ph.D., 1970 Ecology U niversity M icrofilm s, A XEROX C om pany, A nn Arbor, M ichigan

2 THE STRUCTURE OF A SWAMP COMMUNITY IN NORTHERN MICHIGAN AND ITS REACTION TO PARTIAL DRAINAGE By George Ralph Parker A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Forestry 1970

3 ABSTRACT THE STRUCTURE OF A SWAMP COMMUNITY IN NORTHERN MICHIGAN AND ITS REACTION TO PARTIAL DRAINAGE By George Ralph Parker The study was conducted in a swamp community on the eastern edge of Michigan's upper peninsula. It was designed to (1) characterize the present structure of* the primary producers and significant edaphlc factors in a swamp community, and (2) to determine what effects a 6-year-old drainage ditch has had on the site. Quadrats and water wells were located at three distances and on two sites along an existing drainage ditch. Herbaceous and woody shrub species were clipped for biomass, density, and frequency determination. Tree and shrub species were measured for basal area, frequency, and density estimates. Sample stems of Alnus rugosa and Fraxinus nigra were clipped for biomass and production estimates. Foliar samples from dominant species were collected for nutrient analysis. Basal discs of Alnus were used for growth ring analysis. Impermeable soils, physiographic location, and periods of excessive precipitation result in a high water table through much of the growing season. Boils

4 George R. Parker consisted of a shallow layer of black, mucky organic matter underlain by silty clay loam on one site and very fine sand on the other site. The community is enriched by nutrients carried by runoff water from surrounding uplands. This is indicated by nearly neutral ph of the ground water and high X'oliar nitrogen percentages in the five dominant plant species. These edaphic characteristics result in a rich and characteristic flora. More than 100 species were identified on the study area. Alnus rugosa and Fraxinus nigra were dominant overstory species, Cornus stolonifera and Ilex verticillata were dominant shrubs of intermediate height* and the understory was predominated by Glycerla striata and Xmpatiens capensls. Alnus has maintained its dominance on the better drained of the two study sites* while the more poorly drained site is in a transitional stage of succession leading to a swamp-hardwood community. These changes in overstory species have resulted in changes in the understory species. The structure of the community has not been Influenced by either fire or logging for the past 50 years. The above-ground dry weight net primary production for the predominant species was estimated to be 5^5 and 572 g/m2/year for Sites 1 and 2* respectively. Aboveground dry weight biomass (g/m2 ) of these predominant

5 George R. Parker species was 3,235 for Site 1 and 2,451 for Site 2. Predominant species include all herbs, small shrubs,, and the two dominant overstory species. The effect of the drainage ditch on edaphic factors and the structure of the plant community was minor. Differential drawdown of the water table did not vary significantly between 7 and 91 meters from the drainage ditch. However, there was evidence that rate of discharge of surface water is greater near the ditch. Significant decrease in depth of organic matter, increased ph of ground water, increased biomass of herbaceous species, as well as a slight increase in foliar nitrogen for four of five dominant species tested indicate greater rates of decomposition and mineralization are occurring within 40 m of the drainage ditch than farther away. This is partly responsible for a significant increase in number of individuals for the herbaceous species Impatlens capensis. However, there has not been a major change in species composition or a significant shift in biomass among the species. Diversity per individual significantly increased, and redundancy significantly decreased with distance from the drainage ditch based on number of individuals and measured with the factorial expression of the Shannon-Weaver function. However, when biomass per species was used with this function, diversity per individual was not significantly different with distance from the drainage ditch.

6 George R. Parker A growth ring analysis of Alnus indicates that insufficient time has elapsed since construction of the drainage ditch_, and/or its effect has not been great enough to cause a growth response.

7 ACKNOWLEDGMENTS I would like to express my appreciation to Dr. G. Schneider under whose guidance and encouragement this study was conducted, and to the other members of the guidance committee, Dr. W. E. Cooper, Dr. V. J. Rudolph, and Dr. S. N. Stephenson, for their suggestions and reviews of the manuscript. Appreciation also goes to Dr. J. E. Cantlon and Dr. D. P. White for their suggestions in initiating this research, and to Dr. Edward Voss, Professor of Taxonomy, University of Michigan, for his help in identification of the more difficult plant species. Special thanks is extended to Maurice and Vivian Day for making my stay at the Dunbar Forest Experiment Station a very pleasant and memorable experience. Mr. Day's knowledge of the study area and help in establishment of this research project were invaluable. Finally, my greatest thanks and appreciation goes to my wife, Mary Lee. Her encouragement and assistance were essential in completing this viork. ii

8 VITA George Ralph Parker Candidate Tor the Degree of DOCTOR OF PHILOSOPHY Final Examination: September 4, 1970 Guidance Committee: Dr. G. Schneider (Chairman), Department of Forestry Dr. W. E. Cooper, Department of Zoology Dr. V. J. Rudolph, Department of Forestry Dr. S. N. Stephenson, Department of Botany Dissertation: The Structure of a Swamp Community in Northern Michigan and Its Reaction to Partial Drainage Biographical Items: Born September 16, 1942, Tulsa, Oklahoma. Married Mary Lee Williams, 1965* Education: Diploma from Charles Page High School, Sand Springs, Oklahoma, i960 B.S. degree in Forestry from Oklahoma State University, 1964 M.S. degree in Botany from Oklahoma State University, Ph.D. degree in Forestry from Michigan State University, 1970 Professional Experience: Summer employment with Forest Service, U. S. Department of Agriculture, In Idaho and Washington while earning B.S. degree Graduate Teaching Assistant in dendrology and general botany, Oklahoma State University, while earning M.S. degree Graduate Research Assistant, Michigan State University, while earning Ph.D. degree. Professional Organizations*. Society of American Foresters Phi Sigma Society Society of Sigma Xi Xi Sigma PI Ecological Society of America American Association for the Advancement of Science American Museum of.natural History iii

9 TABLE OF CONTENTS Chapter Page I. INT R O D U C T I O N... 1 II. DESCRIPTION OF A R E A... 3 III. METHODS... 6 Abiotic Sampling Procedure... 6 Biotic Sampling Procedure. 11 Analysis of D a t a IV. RESULTS AND D I S C U S S I O N Present State of the S y s t e m Abiotic Factors Foliar Nutrients The Flora Species Importance Successional Change Biomass and Production Effects of D r a i n a g e Abiotic Factors Biotic Factors... 6l V. S U M M A R Y BIBLIOGRAPHY A P P E N D I X iv

10 LIST O F TABLES ace Analysis of Variance Tables for Factors Measured on Two Sites and Three Distances From Drainage Ditch, * Foliar Nutrient Values for the Dominant Species Found on Each Study Site... Importance Values for Herbaceous Species at Three Distances From Drainage Ditch for Both Study S i t e s Percent Frequency of Quadrat Occurrence for Low Shrub and Vine Species on Each Site at Three Distances From Drainage Ditch... Percent Frequency of Quadrat Occurrence for Trees and Shrubs on Two Sites and Three Distances From Drainage Ditch, 19^ Number of Clumps and Stems for Trees and Shrubs on Two Sites and Three Distances From Drainage Ditch, *... Number of Seedlings and Basal Sprouts of Tree Species at Three Distances From Drainage Ditch for Both Study Sites... Importance Values for Tree Species at Three Distances From Drainage Ditch for Both Study Sites... Basal Area for Tree Species on Two Sites at Three Distances From Drainage Ditch... Means and Standard Deviations of Biotic Factors for Site 1 and Site 2, Regressions of Sample Stem Components of Alnus rugosa and Fraxinus nigra on Sites 1 and 2 ^.. Dry Weight Biomass, Net Production, and Relative Distribution by Component Part for Alnus rugosa on Two Sites and Three Distances From Drainage ' Ditch, August, *... v

11 Table Page Dry Weight Biomass, Net Production, and Relative Distribution by Component Part for Fraxinus nigra on Two Sites and Three Distances From Drainage Ditch, August, Dry Weight Biomass, Net Production, and Percent Distribution by Species Category for Each Site. 52 Differences in Abiotic Site Factors and Standard Deviations With Distance From Drainage Ditch, June-July, Rates of Recharge and Discharge From Wells on Site 1 Determined From Continuous Water Level Recorder C h a r t s Mean Monthly Precipitation and Deviation From 20-Year Norm at the Dunbar Forest Experiment Station. 60 Relative Above-Ground Dry Weight and Relative Density for 12 Most Important Herbaceous Species With Distance From Ditch on Each S i t e Means and Standard Deviations of Biotic Factors for Both Sites With Distance From Drainage Ditch, Percent Dry Weight Foliar Nitrogen for Five Dominant Species on Two Sites and Three Distances From Drainage D i t c h Mean Growth Ring Index Values of Sites 1 and 2 for Alnus rugosa at Three Distances From Drainage D i t c h Relative Elevation of Pipe Located at Each We11 and Along Center of D i t c h...83 Relative Elevation of Soil Surface at Each Well and Along Center of Drainage Ditch Average Depth of Organic Matter on Each Quadrat and Average Depth to Mineral Soil Textural Change at Each Well L o c a t i o n PH in the Upper 15 cm of Ground Water Measured at Each Well and Drainage Ditch, June-July, Oxygen (mg/1) in Upper 15 cm of Ground Water in Each-Well and Drainage Ditch, July, 1969 * 85 vi

12 Table Page 27. Weekly Fluctuation in the Water Table and Precipitation for Each Site During the 1969 Growing Season Current Growth Dry Weight, Number of Stems, and Percent of Quadrat Occurrence of Species on Two Sites and Three Distances From Drainage Ditch I/ist of Species Seen on Study Sites But Not Found on Sample Q u a d r a t s Dry Weight, Density and Number of Herbaceous Species Found on Each 1 Q u a d r a t Species Diversity Per Individual and Redundancy for Numbers of Individuals of Herbaceous Species Per 1 Q u a d r a t Species Diversity Per Individual and Redundancy. for Biomass of Herbaceous Species Found on Each 1 Q u a d r a t Current Dry Weight, Density and Number of Woody Species Found on Each 1 Q u a d r a t Basal Area of All Tree Species by Quadrat on Two Sites and Three Distances From Drainage Ditch, Stem and Branch Data for Sample Stems of Alnus rugosa by Site and Distance From Drainage Ditch, T $ 6 9 ' ~ Stem and Branch Data for Sample Stems of Fraxinus nigra by Site and Distance From Drainage Ditch, Dry Weight and Percent Distribution of Bark and Wood for Stem Discs of Alnus r u g o s a Dry Weight and Percent Distribution of Bark and Wood for Stem Discs of Fraxinus n i g r a Macro- and Micro-Nutrient Values for Foliage of Three Dominant Woody Species on Two Sites and Two Distances From Drainage Ditch, July, vii

13 LIST 01*' FIGURES Figure Page 1. Aerial View of Study Area Showing Drainage Ditch and Location of Study Sites (May, 1 9 ^ 9 ) Early Spring View of Drainage Ditch Adjacent to Site 1. Note Species Mixture of Fraxinus nigra and Alnus rugosa on Site to Right of Ditch Early Spring View of Drainage Ditch Adjacent to Site 2. Note Predominance of Alnus rugosa on Site to Left of D i t c h Distribution of Quadrats, Wells, and Precipitation Gauges in Relation to Drainage Ditch for Sites 1 and Precipitation Gauge Located on Cleared Area Near Site AIM2 Quadrat on Line 2 of Site 1 Before Clipping. The Dominant Grass Species is Glyceria striata; Woody Stems are Alnus rugosa A 1 M Quadrat on Line 3 of Site 1 After Clipping of All Above-Ground Herbaceous and Woody Vegetation (<1 cm Basal D i a m e t e r ) Field Determination of Stem Green VJeights for Alnus rugosa and Fraxinus n i g r a Early Spring View of Line 2, Site 1 Showing Variable Ground Surface. Larger Stems Near Center are Fraxinus nigra; Stems in Right Foreground are Alnus "rugosa; Log Is Betula papyrifera Early Spring View of Line 2, Site 2 Showing Ground Surface. Stems are Predominantly Alnus rugosa; Dead Snag in Center Background is Populus balsamif e r a Mean Relative Elevation of Ground Surface and Water Table and Amount of Precipitation Per Week for Both Sites, 1969 *... 2k viii k

14 Figure Page 12, Weekly Relative Water Level With Distance From Drainage Ditch and Amount of Precipitation During 19^9 Growing Season ix

15 CHAPTER I. INTRODUCTION Approximately 100 million acres in bhe eastern United States are classified as poorly drained (Schwab, et al., 1966; Wright, 1907). Much of this area exists in the northern regions where extensive basins possessing poor natural drainage were formed during the last glacial stage. On such lands the high water table is often the dominant factor controlling the structure of the plant community. If these ecosystems are modified through partial drainage,, they should serve as good sites to study the dynamics of the system along the resulting water table gradient. Over the past 100 years, European scientists have gained much insight into the dynamics of poorly drained forest lands when modified by drainage. This was primarily done to increase plant productivity (Holmen, 19*54; Huikari, ; Pyavchenko, 1957)* A review of Forestry Abstracts back to 1955 indicates that while little research was done by American scientists in this area, a great deal of research was conducted during that period by Russian scientists. However, their work, was often not readily available to American Investigaters. This lack of research by American scientists thus far is probably due to the abundance of available productive forest lands. As pressures for more

16 and more forest lands increase* more intensive management of the better forest areas and/or an extension of our management practices into the more marginal areas will be needed. Basic research on lowland areas (bogs and swamps) has been done (Bay* ; Damman* 1964; Heinselman* ; Pierce* 1957; Moss* 1953; V/hite* ; Watt and Heinselman* ; Sjors* 1959; Ritchie* i9 6 0 ; Dansereau and Segadas- Vianna* 1952; Conway* 19^9; and Gates* 1942). More information is now needed in determining the best possible use and management for these lands. Their value for uses such as water recharge areas* wildlife habitat* and genetic pools must not be sacrificed for increased production of wood products to obtain a short-term economic gain (Stoeckeler* 1962; Klawitter* 197^)* To avoid this* research needs to be done to determine their reaction to man's activities. This study is the first part of a long-term research project at Michigan State University* which is investigating the dynamics of a poorly drained ecosystem when subjected to man's management practices. The objectives of this study were to (1) characterize the present state of the system* and (2) to determine what effects an existing drainage ditch has on the structure of the plant community.

17 CHAPTER II. DESCRIPTION OP AREA The study was conducted during 1968 and 1969 on the Dunbar Forest Experiment Station located in Chippewa County on the eastern edge of Michigan's upper peninsula. The area can be characterized by Isolated, low, rounded ridges or hills intersected by broad, swampy valleys and lakes (Veatch, 1927). Most of the present surface features are the result of glacial drift and lacustrine deposits laid down during the last glacial stage. The general climate of the area has a short growing season with moderate summer mean temperatures of 63 P and long, frequently rigorous winters. Annual precipitation averages about 31 inches, with somewhat greater amounts occurring in the summer and fall than in the viinter and spring. Average snowfall is about 96 Inches (Climatological Summary, ). The frost-free season averages about 116 days, but light frosts may occur throughout the growing season. The prevailing winds are westerly. One of the many glacial basins located in the area served as the study location. The basin extends north and south with a parallel sandy and gravelly ridge located between it and the St. Mary's River (Figure 1). Soils vary

18 1. AERIAL VIS'/I OF STUDY AREA SHOWING DRAINAGE DITCH AND LOCATION 1969).

19 from very Tine sand to silty clay overlain with shallow deposits of peat and muck* Impervious soils, poor natural drainage, and drainage from surrounding uplands onto the area combine to create its present edaphic characteristics. Mr. Maurice Day, research forester on the station, relates that logging and fire have been excluded from the area for over 30 years. The vegetative type is classified as a shrub-carr (Curtis, 1959; White, ). Alnus rugosa and Fraxinus nigra are the principal overstory species, and Cornus stolonifera the main low shrub. Principal ground vegetation genera are Carex, Glyceria, Impatiens, Aster, and Solidago, similar to that described for a sedge-alder swamp by Damman (1964).

20 CHAPTER III. METHODS Abiotic Sampling Procedure During the summers of 1961 to * & shallow drainage ditch (40 cm mean depth) was plowed through the center of the study basin (Figures 2 and 3 ). Drainage of the water in the ditch moves in two directions; to the north and to the southj both sections of the ditch emptying into the St. Mary's River. The study area drains to the south. Two study units were first located on aerial photographs, then located in the field using recognizable landmarks found on the aerial photographs. Each unit extends 130 meters (m) adjacent to and 92 m perpendicular to the ditch (Figure 4). Available soil maps indicate a Bergland silty clay loam on one area (Site 1), and a Bruce very fine sandy loam on the other (Site 2 ).1 Four 1 m water wells were randomly located along each of three lines which parallel the ditch at distances of 7.6 m (Line 1), 45*7 m (Line 2), and 91.4 m (Line 3) to determine the effectiveness of the ditch in lowering the water table. Wells were not placed within any sample U. S. Department of Agriculture, Soil Conservation Service soil survey,

21 7 FIGURE 2. EARLY SPRING VIEW OF DRAINAGE DITCH ADJACENT TO SITE 1. NOTE SPECIES MIXTURE OF FRAXINUS NIGRA AND AT.NUS RUGOSA ON SITE TO RIGHT OF DITCH. FIGURE 3. EARLY SPRING VIEW OF DRAINAGE DITCH ADJACENT TO SITE 2. NOTE PREDOMINANCE OF ALNUS RUGOSA ON SITE TO LEFT OF DITCH.

22 8 Site 1 a Quadrat Well = Drainage Ditch o Precipitation Gauge * Direction or Hater Plow I'* 7.Sen Site 2 I 7.6m J 38.1a O - - * r O D 03 FIOURE DISTRIBUTION OF QUADRATS, WELLS, AND PRECIPITATION GAUGES IN RELATION TO DRAINAGE DITCH FOR SITES 1 AND 2.

23 quadrat to avoid disturbance of the vegetation. A 3-f t length of sbeel pipe was driven into the soil beside each well, and four similar pipes were placed in the center of the ditch along each study site. An aluminum tag, designating area, line and well number, was placed on each of the steel pipe markers. The relative elevation of the top of each pipe was then determined with a transit and stadia rod to use as a reference elevation for measuring the fluctuation of the water table. Shelters for Belfort continuous water level recorders were located over one well on each line of Site 1 to obtain an estimate of rates of recharge and discharge of the water from the area. Two functional recorders were available for use; one was placed on l.ine 1 for the entire summer, and the other was rotated between bines 2 and 3* A precipitation gauge was located near each of the study units in a cleared area. All obstructions were removed by a distance at least three times their height from the gauge (Figure 5) Water levels in the wells and precipitation measurements were made weekly throughout the 1969 growing season, except during one period of very intensive precipitation when water levels were the highest recorded on both study sites. The ground water from ditch and well points was analyzed for both oxygen, in milligrams per liter (mg/1), measured in the field with a portable galvonic cell oxygen analyzer, and ph, measured with a Beckman electrode in the

24 FIGURE 5. PRECIPITATION GAUGE LOCATED ON CLEARED AREA NEAR SITE 2.

25 11 laboratory. All measurements were made in the upper 15 centimeters (cm) of the ground water. Soils were checked in the field down to 100 cm, and depths of organic matter and changes in texture and structure were noted. The study area was flown in May, , to observe the physiographic features, the study sites, and for a photographic record. Weather balloons, four feet in diameter, were used to mark the corners of the study sites. Biotic Sampling Procedure Within each study unit, ten 4 by 4 m quadrats were randomly located along each of three lines which parallel the ditch. Bach quadrat was permanently marked with a 3-foot length of steel pipe and numbered with an aluminum tag designating the study site, line, and quadrat number. A one square meter quadrat vias located in each of the larger quadrats utilizing the steel pipe marker as one of its corners. All plant species found on the two sites were identified (Fernald, 1950)9 and specimens placed in the Beal-Darlington herbarium at Michigan State University for future reference. Woody species less than 1 cm basal diameter and herbaceous species were sampled on each 1 m^ quadrat (Figures 6 and 7)* Density, frequency, and above-ground dry weight biomass were determined for each species found. All clipping was accomplished in two weeks during the

26 12 FIGURE 6. A I M 2 QUADRAT ON LINE 2 OF SITE 1 BEFORE CLIPPING. THE DOMINANT GRASS SPECIES IS GLYCERIA STRIATA; WOODY STEMS ARE ALNUS HUGOSA. FIGURE 7. A I M 2 Q.UADRAT ON LINE 3 OF SITE 1 AFTER CLIPPING OF ALL ABOVE-GROUND HERBACEOUS AND WOODY VEGETATION («Cl CM BASAL DIAMETER).

27 13 period oi' maximum above-ground biomass (late July and early August). Site 2. Quadrats on Site 1 were clipped before those on The order of clipping quadrats was randomly assigned to minimize sampling error due to temporal changes in the vegetation. Samples were first air dried and then oven dried at 105 C for 24 hours before weighing. A collapsible 1 m2 plot frame similar to that described by Blair (1963) was used to delimit the edges of each quadrat. Diameters at breast height (1.37 ni) were measured with calipers for each stem of all tree species on each of the 4 by 4 m quadrats. The dominant high shrub^ Alnus rugosa3 was measured as a tree. Each stem of each clump for this species was measured separately, and number of clumps per quadrat were tallied. Heights of Alnus and Fraxinus were measured to the nearest 0.5 m. Less abundant shrub species were counted individually or by clumps. Above-ground biomass determinations of Alnus and Fraxinus were made on three of the ten 4 by 4 m quadrats that were randomly selected on each line. One stem from each 2 cm size class found on each quadrat was clipped to obtain the range of size classes for each species. To avoid sampling bias, the stem located farthest to the north on each quadrat for each size class was taken as the sample stem. Stems occurring on quadrats other than the biomass quadrats, but which constituted a larger size class, were also sampled.

28 14 A chain saw was used to cut each stem at ground level. Branches were clipped from the stem and separated into five size classes. A representative branch was selected from each size class and separated into fruit and flowers, current growth (twigs plus leaves), live wood and dead wood. Total length was measured to the nearest 10 cm for each representative branch, and basal discs were clipped from all remaining branches. Diameters (outside bark) were measured to the nearest 1 millimeter (mm) just above the butt swell for each of the five representative branches and for all basal discs from the remaining branches. The last five growth rings were measured to the nearest 0.1 mm. for each representative branch to determine wood production by weight (Whittaker, 1965)- All growth rings were measured on branches less than 5 years of age. Component parts were then oven dried at 105 C to constant weight. After removal and field measurement of all branches, the stem was measured for total length (nearest 0.5 m) and cut into 1 m sections. Total green weight was determined to the nearest 1.0 gram (g) (Figure 8). taken from each 1 m section and weighed. Sample discs were Laboratory measurements of the stem discs included bark thickness, diameter (inside bark), width of last six growth rings (growth ring for 1969 measured separately), and oven dry weight (105 C to constant weight). A representative sample of the stem discs from each species was separated into wood and bark for oven dry weight ratio determination. Moisture

29 FIGURE 8. FIELD DETERMINATION OF STEM GREEN WEIGHTS FOR ALNUS RUGOSA AND FRAXINUS NIGRA.

30 16 contents of stem discs were used to determine total dry weight for each sample stem. Methods of woody stem analysis generally follow those of Whittaker and Woodwell (1968, 1969) Foliar samples were collected from the dominant woody an^ herbaceous species for nutrient analysis (Kenworthy, 1964; White, 1958). Analysis of samples was made in the Plant Analysis Laboratory at Michigan State University. Nitrogen was determined by the micro-kjeldahl method, potassium by flame photometer, and all other elements by direct-reading spectrograph. Sixty basal stem discs (one from each quadrat) of Alnus rugosa were collected in mid-september, 1969, for a growth ring analysis. Discs were air dried, sanded with 300 grid paper, and marked into four quadrats (Stokes and Smiley, 1968). Ring width along each of these marks was measured to the nearest 0.1 mm. Analysis of Data All data were entered on computer forms and punched on cards for analysis. The Michigan State University Agricultural Experiment Station Computer Stat Series was used for statistical analysis and computation of regression equations. Where necessary, programs were written to perform other computations. Orthogonal comparisons were made for species differences betvieen quadrat lines and for water levels, ph and oxygen

31 17 in wells at the three distances from the ditch. The statistical design is a randomized complete block utilizing the study sites as blocks and the lines of quadrats and wells as treatments (Steel and Torrie, i9 6 0 ). The following calculations were made on data collected for each species: 1. Herbaceous species p a. Above-ground dry weight (g/m ) b. Density (no/m2) c. Frequency of quadrat occurrence (%) d. Importance value (relative dry weight + relative density + relative frequency, the sum f 3) e. Total number of individuals (N), number of individuals per species (n^), and number of species (S) found on each ms quadrat were used to calculate community diversity (D), diversity per individual (D), maximum diversity (Omax)> minimum diversity (Dm ^n ) and redundancy (R) in the following equations (VJilhm., 1967; Patten, ; Pielou, 1966; Margalef, 1969): s D = log Ni -*51 log n< ] 1=1 D = (i)(log Ni - log n±!) Dmax = los Ni - s log ( ) i Dmin = 1 S Ni - log N - (s - 1)J

32 l8 cmax " % i n These same equations were then used to compute equivalent values based on biomass for each species per m (Wiliam* 1968; Dicltman* 1968). 2. Woody shrubs (<1 cm basal diameter) and trees (<1 cm d.b.h.) n a. Above-ground dry weight (g/m ) separated into current and previous growth b. Density (no/m^) c. Frequency of quadrat occurrence {%) 3. Shrub species (>1 cm basal diameter) a. Density (clumps and individual stems/ha) b. Frequency of quadrat occurrence ($) 4. Tree species a. Density (clumps and individual stems/ha) b. Frequency of quadrat occurrence c. Basal area (m2/ha) d. Importance value (relative basal area -t- relative density + relative frequency* the sum ~ 3 ) 5- Alnus rugosa and Fraxinus nigra a. Above-ground dry weight (g/m^) (1) Stems - Percent moisture of stem discs and total stem green weight were used to estimate total dry weight; for each sample stem. Linear regressions of estimated total dry weight on parabolic volume (stem basal area X tree height* the product 7 2) were computed separately

33 19 for the two species on each site. These regressions, wood/bark weight percentages and parabolic volumes for stems on each quadrat were used to determine total dry weight (g/m2 ) for the two species on each line of the two study sites. Total volume of wood per sample stem for each 1 m section was computed using the Smalian formula (means of the areas, inside bark., at the end of each 1 m stem section times the length). Volumes of sections were then summed to obtain the total wood volume for each sample stem. The volume of wood included in the mean increment for the last five years, not including 19^9 growing season due to early sampling date, was computed for each stem section with the following formulas: V = (a^ + a2)l a^ = area of mean increment at the end of stem sections A = area of wood at end of each stem section r = mean width of growth rings at end of stem section R = mean radius at end of each stem section V = volume increment L = length of stem section Volume increments for each stem section were then summed to give total growth volume for each sample tree. Regressions 2 of the volume estimates on DBH 4- DBH were used to compute

34 20 volume of wood ( c m V m 2 ) and volume increment (cm3/m2/year) for the two species on each line of both study sites. An estimate was made of stem wood weight produced (g/m2/year) by: Est. Total Dry VJt. (g/m2 ) X Est. Vol. Increment (cm3/m2/year) Total Wood Vol. (cm3/m2 ) (2) Branches - Independent estimates of current weight (twigs + leaves) and dry wood weight + bark for branches of each sample stem were obtained by regressing the log10 of 10 times current dry weight and the log1q of lo times dry wood weight + bark on the log1q of 10 times the basal diameter of each representative branch for each species on each site, and by using these regressions along with basal diameters of all branches on each sample stem. Estimated dry weights of current growth and wood + bark for branches of each sample stem were then regressed on DBM + DBH2 for each stem by species and site. These regressions were then utilized to compute total current p growth and wood weight + bark of branches per m c for both species on the two sites. Annual weight increment of representative branch wood + bark was obtained by regressing the log-^q of 10 times the mean weight of the last five growth rings including bark (less than five rings in younger branches) on the log10 -*-0 times the basal diameter. Total branch wood increment for each stem was then computed utilizing basal diameters of all branches on each stem and the above

35 21 regressions. This total was then regressed on DBH + DBH2 of each sample stem to obtain an estimate of branch wood + bark, weight increment (g/m2/year) for each species on each site. Branch data were multiplied by 10 to avoid zeros when taking the log of 1. b. Growth ring analysis of Alnus - A growth ring index was computed for two of the growth ring width series measured on the basal discs of Alnus as outlined by Pritts (1966). Index values correct for variability in width of rings due to factors other than climate, such as age and crown size. It does not eliminate such variability as sampling error. Index values were computed by first regressing each ring width series on year and then dividing the actual ring width into its corresponding value on the regression line. The two index values for each year on each stem were used to obtain an average Index value per quadrat.

36 CHAPTER IV. RESULTS AND DISCUSSION Present State of the System Abiotic Factors The ground surface on the two sites iu typical of poorly drained areas with hummocks and depressions scattered throughout (Figures 9 and 10). The average soil surface slopes about 1 percent on both study sites. Downslope is to the east on Site 1 and to the west on Site 2. Mean depth of the black, mucky organic layer (includes A^ horizon) was 25.6 cm on Site 1 and 27.0 cm on Site 2. This was underlain by a 10 to 15 cm strongly leached, blue- gray A^ horizon on both sites. The A^ plus the B horizon on Site 1 was a silty clay loam texture and averaged 62 cm in thickness. This corresponds to a very fine sand horizon on Site 2 which averaged 52 cm. Little variation was found in thickness of the A2 and B horizon over each study site. Total precipitation measured from June 18 to September 17 during the 1969 growing season was 2 5.^ cm (Figure 11). Amounts measured on the two sites never varied more than 0.3 cm and were well distributed over 22

37 23 FIGURE 9. EARLY SPRING VIEW OF LINE 2, SITE 1 SHOWING VARIABLE GROUND SURFACE. LARGER STEMS NEAR CENTER ARE FRAXINUS NIGRA: STEMS IN RIGHT FOREGROUND ARE ALNUS RUGOSA: LOG IS BF.TULA PAPYRIFERA. FIGURE 10. EARLY SPRING VIEW OF LINE 23 SITE 2 SHOWING GROUND SURFACE. STEMS ARE PREDOMINANTLY ALNUS RUGOSA: DEAD SNAG IN CENTER BACKGROUND IS POPULUS BAISAMIFERA.

38 24- PPT (cm) Relative Elevation (cm) Relative Elevation (cm) Site 1 Ground Surface Site 2 Ground Surface JL n IL IL n 6/10 7/2 7/16 7/30 0/13 Q/27 9/10 Date of Measurement FIGURE 11. MEAN RELATIVE ELEVATION OF GROUND SURFACE AND WATER TABLE AND AMOUNT OF PRECIPITATION PER WEEK FOR BOTH SITES,

39 25 the growing season except for two-week periods in mid-july and late August. Recharge of the water table with precipitation depended on its initial height at the time precipitation started and the duration and intensity of the precipitation (Figure 11). Bay (1966) found this same relationship in bogs of northern Minnesota. If the water table was near the soil surface at the time precipitation occurred3 height of net water table rise was less, due to more direct runoff, than if the same precipitation occurred when the water table was well below the soil surface. This assumes the same moisture conditions in the overlying soil stratum. Both sites remained wet through the middle of July for the 1969 growing season. During this period the mean water table was 2.8 and 11.5 cm below the soil surface on Sites 1 and 2, respectively. This difference was significant (e<=.01) (Table 1). During this wet p e r i o d d e p r e s s i o n s in the soil surface remained inundated while most of the hummocks remained exposed; however, contrast between hummocks and depressions was not as great on Site 2 as on Site 1, probably due to better drainage characteristics on Site 2. Both sites were completely Inundated on June 27 after a very intense rainfall. After July 16, water levels began to drop more rapidly due to decreasing amounts of precipitation and increasing evapotranspiration rates. Water levels on Site 2 dropped to below 60 cm of the soil surface by

40 TABLE 1. ANALYSIS OF VARIANCE TABLES FOR FACTORS MEASURED ON TWO SITES AND THREE DISTANCES FROM DRAINAGE DITCH Rep Rep Line Line Line Hell Remaining Rep X X X X X X Error (Site) Line Quad Line Quad Quad Hell Week Hell Week Week (df) Degrees of Freedom (df) Herbaceous Species Dry Height T * T T T T 18 Stems * *** jp# * * T 18 Species T T T T T 18 Dive r s i ty/ind ivid ua1 #** T T T T 18 Stems Redundancy (Stems) *** *** T T T T 18 Diversity/Ind ividual T T T T T T 18 Biomass Redundancy (Biomass) ** * T T T T 18 Tree Species Basal Area * T T T T T 18 Relative Elevation of *** ***- T *** T T T 101 Hater Table Depth of Hater Table T T *** f T T 101 Oxygen in Ground Hater T T T T T 9 ph of Ground Hater *** * T T T 9 Organic Matter Depth T * T ** T 27 * Significant at.10 ** Significant at.05 *** Significant at.01 T Tested for factor but not significant

41 July 24 and remained there for the rest of the growing 27 season except for a wet period in early August. Water levels decreased more slowly on Site 1 due to its less permeable soils and physiographic location. Site 1 drains an extensive basin and its surrounding uplands, while Site 2 drains a much smaller area (Figure 1). Other studies have shown similar sites to be fairly eutrophic due to the high nutrient content of incoming ground water from surrounding uplands (Heinselman, 1963j 1965; Bay, 1967). Fierce (1957) believes the relatively high productivity of tree species and stand composition on these sites to result from high levels of dissolved salts and oxygen carried in drainage waters. He found ph to vary from 6.0 to 7.5 and oxygen levels from 0.9 to 4.6 ppm in the upper 15 cm of the ground water. Oxygen levels in this study were found to vary from mg/1 on Site 1 to mg/1 on Site 2. Mean ph was on Site 1 and on Site 2. Foliar Nutrients Comparison of foliar nutrient values with those found in other studies gives further evidence that this system is eutrophic (Table 2). Watt and Heinselman (19&5) have shown foliar nutrient percentages to be correlated with site quality. They show a decrease in foliar percentages of nitrogen and phosphorus for black spruce with distance from a dense speckled alder stand to a black spruce

42 28 muskeg. Moizuk and Livingstone ( ) present foliar nitrogen values for red maple seedlings taken from a bog mat and for those grown in a complete nutrient culture. Percent nitrogen for those from the mat averaged less than 1,0 * while those grown in nutrient culture averaged greater than 3 *0 * TABLE 2. FOLIAR NUTRIENT VALUES FOR THE DOMINANT SPECIES FOUND ON EACH STUDY SITE Species Alnus rugosa July 1968*(2 )D Aug (6) Fraxinus nigra July 1968 (2) Aug (6 ) Site 1 Element (Percent Oven Dry Weight) N P K Ca Site site Site Site Site _c Site Site Cornus stolonifera July 1968 (2) Glyceria striata July 1969 (6) Impatiens capensis July 1969 (6) a Samples collected in July and August 6 Number of samples in each nutrient value c No analysis made

43 29 Foliar analyses of tree species are not always an indication of the fertility level in soil (Wilde, 1958). however, foliar nitrogen percentages for all species sampled were in the upper part of the range given for red maple seedlings by Moizuk and Livingstone discussed above. These high levels of nutrients found in the five dominant species - tree, high shrub, medium shrub, grass and annual - of this community indicate this site to be richer in available nutrients than similar stagnant water systems. The Flora The combination of such edaphic factors as nearly neutral ph, high nutrient content, high fluctuating water table, and good aeration result in a rich and distinct flora (SJors, 1959» Conway, 1949) A search of the flora on both sites revealed 109 species, 6l genera, and 31 families. Gramineae was the most represented family with 10 genera and 15 species, and Carex with 17 species was the most represented genus. Of the 109 species found, 29 did not occur on any sample quadrats. These species were either rare in occurrence or were located only along the ditch banks. Damman1s (1964) description of a sedge-alder swamp in central Newfoundland presents edaphic factors and a species composition very similar to those found in this study. Glyceria striata, which was a dominant grass species on both study sites, was

44 30 only of minor importance; and Fraxinus nigra, a dominant tree species, was absent from Damman's species lists. Species Importance Importance value is believed to be a better indication of a species' structural importance since it combines distribution, size and number or individuals (Curtis and McIntosh, 1951; Rice, 1965)- However, it is not necessarily an indication of a species' functional importance in the community. Importance values for herbaceous species Involve relative dry weights, relative densities, and relative frequencies; those for tree species include relative basal area, relative densities, and relative frequency. Frequency was determined from quadrat occurrence. All stems which originated below 1.37 m were sampled as Individuals for woody species, and clumps were used as individuals in grass and sedge species. VJoody species which had a main stem greater than 1 cm at 1-37 ni were considered a tree. Of the 57 herbaceous species sampled, 16 were well distributed over both study sites (Table 3). Glyceria striata and Impatiens capensis vie re the most important species sampled. High importance values for Glyceria are primarily due to its large relative dry weight, vihile those for Impatiens are due to large relative densities. Glyceria is a grass which occurs as clumps, vihile Impatiens is a very succulent single-stemmed annual. Impatiens vias more important on the better drained soils of Site 2 than

45 31 TABLE 3. IMPORTANCE VALUES FOR HERBACEOUS SPECIES AT THREE DISTANCES FROM DRAINAGE DITCH FOR BOTH STUDY SITES Distance from Ditch Species 7.6m 45. 7m 9 1.4m Site 1 Site 2 Site 1 S'I'te 2 Site 1 S'ite '2._ Agrostis perennans 0.74 Arisaema atrorubens Aster lateriflorus A. puniceus A. umbellatus Bromus c H i a t u s Calamagrostis canadensis I Caltha palustris Cardamine pensylvanica 0.42 _ Carex canescens C. crinita 0.48 C. disperma O.38 C. gracillima o C. hystricina C. interior C. intumescens O C. leptalea C. leptonervia C. projecta 1.08 O C. stipata C. tribuloidcs O C. Tuckermani 2.20 C. vesicaria 5.18 Chelone glabra 0.47 o.4i Cicuta bulbifera Cinna arundlnacea C. latifolia Dryopteris spinulosa Epilobium. glandulosum 2.22 l.4o Equisetum arvense Eupatorium _ maculatum E. purpureum Fragaria virginiana Galium palustre G. tinctorium G. tririorum H 00 0*

46 32 TABLE 3 (cont'd) Distance t'rom Ditch ~ Species 7. bin 45 -Tin 91.4m Site T- S"it'e"'2 Site" 1' Site "2 'Site l"site Glyceria striata llabenaria psycodes Ifieracium aurantiacum Impatiens capensis Iris versicolor Lactuca biennis Lycopus uniflorus Maianthemum canadense Mitella nuda Molinia caerulea Onoclea sensibilis Ranunculus abortivus R. recurvatus Rumex orbiculatus Scutellaria lateriflora Senecio aureus Smilacina trifolia Solidago rugosa Stellaria graminea Viola cucullata V. pallens ; N O : _ O I a Relative dry weight + relative density + relative frequency, the sum ^ 3

47 33 on Site 1, while Glyceria was fairly constant in importance over both sites. The next most important species were Senecio aureus and Solidago rugosa. Arisaema atrorubens and Habenaria psycodes were found on Site 1 only. It appears their distribution is limited to the more poorly drained Site 1. The distribution of other rarer species may be actual, but may also be due to sampling error. It should be pointed out that importance values are valid only during that part of the season (late July) when data were collected. An earlier or later sampling date would probably result In a shift of importance values among species due to vernal changes. Curtis (1959) discusses three aspects of such communities occurring in early spring, mid-summer, and late fall. Species such as Caltha palustris dominate the view In early spring. Midsummer brings the flower of orchids, grasses and sedges. Solidagos and Asters dominate the late fall aspect. Low shrub and vine species were minor in importance compared to herbaceous species in this community except for localized areas (Table 4). Clematis virginiana was the only vine found which was common on both sites. It usually dies back: to a low woody base each winter, but grows rapidly during the summer, overtopping crowns of overstory species in a few instances. Ribes americanum was the most common of the four Ribes species found, but still minor In occurrence. Rubus idaeus apparently does

48 34 best on the better drained soils of Site 2, while Rubus pubescens occurs commonly over both sites. This latter species is one that is found almost exclusively on hummocks, but sends out runners to colonise depressions during the drier summer seufc.cn. TABLE 4. PERCENT FREQUENCY OF QUADRAT OCCURRENCE FOR LOW SHRUB AND VINE SPECIES ON EACH SITE AT THREE DISTANCES FROM DRAINAGE DITCH Distance from Ditch Low Shrub & 7. 6m 45': 7m 91.4 m Vine Species Slt'e 1 Site 2 Site 1 Site 2 Site l Site 2 Clematis virginiana Rhamnus alnifolia Ribes americanum R. glandulosum R. hirtellum R. triste Rubus idaeus 10 4o R. pubescens 6o o 80 Cornus stolonifera was the most prevalent species in the second story of the community (Table 5) Alnus is considered to be a third-story species since it dominates the crown surface of the community. Ilex verticillata, the only other second-story shrub sampled, was not found on Site 2.

49 35 TABLE 5- PERCENT FREQUENCY OF QUADRAT OCCURRENCE FOR TREES AND SHRUBS ON TWO SITES AND THREE DISTANCES FROM DRAINAGE DITCH, 19^9 Species Distance from Ditch 7.bm 45 7m 91.4m Site 1 Site 2 Site 1. Site 2 Site 1 Site 2 Tree Species8 Abies balsamea Alnus rugosa O O0 100 Betula papyrlfera Fraxinus nigra Larix laricina Populus balsamifera o 30 Prunus virginiana o Salix gracilis S. pyrifolia S. serissima Ulmus americana o - 10 Viburnum trilobum Shrub Species13 Cornus stolonifera 4o o 70 Ilex verticillata f* Steins > 1 cm d.b.h. b Stems > 1 cm basal diameter

50 36 Table 6 emphasizes the basal sprouting characteristic of the dominant woody species in this community. The tight canopy, heavy herbaceous cover, and poor moisture conditions found in these communities are not conducive to high seedling survival. Table 7 gives some indication of the number of new seedlings and sprouts occurring on the sites. They seem to be in sufficient number for Alnus to maintain its dominant position in the community. Distribution of seedlings and sprouts for Fraxinus and Fopulus correspond with the present distribution of old established trees. The presence of Populus on the 7.6 m transect of Site 1 was due to nevj seedlings. The same is also true for Ulmus americana on the 45.7 m transect of Site 2. This species occurred on Site 1 also, but was rare in occurrence. Of the 12 tree species sampled, only two were well distributed over both study sites (Table 8). Alnus rugosa, a high shrub, was the most important, and Fraxinus nigra was next most important. Site 2 was more heavily dominated Alnus than was Site 1. All other tree species were sporadically scattered over the sites. Fopulus balsamifera and Larix larlcina were mostly large, over-mature individuals which resulted in large basal areas and importance values (Table 9)* Successional Change It appears that much of Site 1 is In a transitional stage of succession leading from an Alnus-dominated

51 TABLE 6. NUMBER OF CLUMPS AND STEMS FOR TREES AND SHRUBS ON TWO SITES AND THREE DISTANCES FROM DRAINAGE DITCH, 1969 _ Distance from Ditch 7.6m AE.7m Q1.4m Species Clumps Steins Clumps Stems Clumps Stems (no/ha) Tree Species8 Abies balsamea Site Site Alnus rugosa Site 1 3,687 10,812 3,687 9,688 4,125 15,562 Site 2 3,625 ll,2p0 3,562 10,125 3,750 12,437 Betula papyrifera Site Site Fraxinus nigra Site 1 2,000 2,375 3,687 4,063 3,375 3,875 Site ,000 3, Larix laricina Site Site Populus balsamifera Site ,125 1,312 Site Prunus virginiana Site Site Salix gracilis Site Site

52 TABLE 6 (cont'd) Distance from Ditch 7.6m 46.7m 91.4m Species Clumps Stems Clumps Stems Clumps Stems Tree Species (cont'd) Salix pyrifolia Site o3 125 Site Salix serissima Site 1 2p0 43? Site Ulmus americana Site Site Viburnum trilobum Site Site Total Tree Species Site 1 6,125 13,812 7,499 13,876 9,126 21,500 Site 2 4,063 11,688 7,812 14,937 4,938 13,938 Site Average 5,094 12,750 7,656 14,406 7,032 17,719 Shrub Speciesto Cornus stolonifera Site , Site ,750 4,187 1,312 4,125 Ilex verticillata Site , Site Total Shrub Species Site 1 1,062 2, Site ,750 4,187 1,312 4,125 Site Average 594 1,562. 1_,125_ 2, ,338 a Stems >1 cm d.b~.hu to Steins >1 cm basal diameter