The North Springfield Bog, Springfield, VT: Is it really bogged down? A Master s Project Presented By. Corinna Photos

Transcription

1 The North Springfield, Springfield, VT: Is it really bogged down? A Master s Project Presented By Corinna Photos Approved as to style and content by: Advisor, Rachel Thiet, Ph.D. Antioch University New England Date Antioch University New England Department of Environmental Studies December 2007

2 The North Springfield, Springfield, VT: Is it really bogged down? A Masters Project Presented to the Department of Environmental Studies Antioch University New England In Partial Fulfillment Of the Requirements for the Degree of Masters of Science By Corinna Photos December

3 2007 All Rights Reserved 3

4 TABLE OF CONTENTS LIST OF TABLES...5 LIST OF FIGURES...6 LIST OF APPENDICES...7 ACKNOWLEDGMENTS...8 ABSTRACT...9 BOG AND FEN COMMUNITY COMPOSITION...11 INFLUENCES OF PH ON VEGETATION COMPOSITION...13 HYDROLOGY...18 THE NORTH SPRINGFIELD BOG...19 GOALS & OBJECTIVES...21 METHODS...22 SITE DESCRIPTION...22 VEGETATION ANALYSES...22 PH AND HYDROLOGY ANALYSES...23 DATA ANALYSIS...25 RESULTS...26 DISCUSSION...30 CONCLUSION...35 REFERENCES...37 APPENDICES

5 LIST OF TABLES 1. Ranges and means of ph for Sphagnum species from Maine, New Hampshire and Vermont. Measurements were obtained from Sphagnum-dominated peatlands over the course of several summers (McQueen 1990) Peatland classification & ph ranges Community dominance, wetland classification, and ph range

6 LIST OF FIGURES 1. North Springfield, Springfield, VT June Means of ph by community. Bars represent standard deviation. A significant difference was found among each of the community types, with all community combinations ph distribution among the varying communities. The solid line on July 11, 2007 represents the fall of the Acer rubrum on the sedge community Community hydrologic fluctuation data combined with precipitation records from the Hartness State Airport in, Springfield, VT

7 LIST OF APPENDICES 1. Peatland species and their peatland classification Species found in the NSB and their classification based on literature searches Species List for the NSB and corresponding ph ranges and National Wetland Plant Indicator Status Community dominance and species cover (percent) for the NSB

8 ACKNOWLEDGMENTS They say it takes a village to raise a child and I think the saying should also apply to the completion of this project. First and foremost I would like to thank Bob Lichvar of CRREL, ERDC Army Corp of Engineers for mentoring me through this process. His help was invaluable from the location of the study, to the input on study design and the purchase of equipment. My biggest helper (who knew getting fence posts out of a bog would be so hard) and cheerleader, Nada Wigand, I can not thank you enough for your help. I would also like to thank Kristy Hopenspburger for her statistical help and encouragement. To all the individuals at CRREL, ERDC Army Corp of Engineers in Hanover, NH for their help with equipment, Chris Williams, Chris Berini, Jay Clausen, Doug Punt, Nate Larmie, Tom Hall, and Kate White. Thank you to the Ascutney Mountain Audubon Society, especially to Marianne and Michael Walsh for their help and authorization to use the North Springfield. Thank you to Rachel Thiet, a great advisor who kept me on my toes with deadlines. Thanks to my parents and family who have supported me throughout my grad school process, thank you for supporting my dreams. 8

9 ABSTRACT In regards to composition and distribution, the vegetation within the North Springfield (NSB) in Springfield, VT does not exhibit vegetation typical of a Vermont Boreal kettle bog, as it is currently defined by the Ascutney Mountain Audubon Society. The goal of this study was to more accurately classify what is currently called the NSB and assess possible factors influencing species composition and distribution. The three distinct plant communities and an open water area within the NSB were sampled for percent cover. In addition to vegetation composition, ph, hydrologic fluctuation and temperature were recorded for each of the three plant communities and the open water area. A significant difference in ph between communities was found and positive correlations existed among ph and temperature, ph and hydrologic fluctuation, and precipitation and hydrologic fluctuation; however aside from the correlation between ph among each community, all other correlations were too weak to conclude cause and effect relationships. Given the significant difference in ph among each community and the ph ranges of the given communities I hypothesize that the NSB is transitioning into a poor fen. While peatland succession typically follows a fen to bog succession there have been studies that document a reversal of this process, and evidence suggests that this could be the path that the NSB is following. One theory for a reversal of this process is due the input of groundwater. While the current mapping of hydrographs and their relation to precipitation shows no evidence to suggest that the bog-fen has an input of groundwater; to accurately access the possible influence of groundwater input, monitoring wells would need to be installed. Further study of the NSB is necessary to make stronger connections regarding the factors affecting the community composition 9

10 and distribution, perhaps a task that can be accomplished by the area schools that utilize the NSB as nature s schoolhouse. 10

11 INTRODUCTION The North Springfield does not exhibit vegetation typical of a Vermont Boreal kettle bog, as it is currently defined by the Ascutney Mountain Audubon Society (Thompson & Sorenson, 2000). The vegetation found within the bog upon initial observation has vegetation that is typical of both bogs and fens, ranging from Sphagnum and pitcher plants to freshwater sedges and shrubs (Lichvar, 2007). If this bog does not exhibit typical kettle bog vegetation, what is a more representative term that would encompass the current vegetation composition? What are the driving forces affecting the vegetation composition and distribution? To attempt to answer these questions, the proposed study will evaluate the relationship between ph, hydrology, and vegetation community structure and distribution at the North Springfield, VT. The objectives of this study were: 1) Sampling and mapping the distinct plant communities in the Springfield, 2) Quantifying the ph of the three distinct plant communities and 3) Monitoring water fluctuation in the three distinct plant communities. and Fen Community Composition In order to determine if the classification term bog applies to the North Springfield it is necessary to address the definition of a peatland. A peatland is defined by Mitch and Gosselink (2000) as a type of wetland that consists primarily of partially decomposing organic matter. Peatlands are generally classified as bogs or fens and are most often delineated based on their nutrient availability and hydrologic input and output. Peatland definitions are determined through various classification techniques. Peatland classification techniques are typically based on the following characteristics: successional development, phytosociology, nutrient status and floristics, and hydrology, 11

12 chemistry and floristics (Crum & Planisek, 1988). Two classifications used in the Northeastern U.S. look at the relationship between water and nutrient characteristics and the other classifies a peatland based on its position within a landscape based on an ecological perspective (Johnson 1985). Based on water and nutrient characteristics a peatland is classified into five categories; Geogenous, Mineotrophic, Ombiogenous, Oligotrophic, and Eutrophic. A Geogenous, or earthoriginating, peatland is a peatland that is fed primarily by groundwater or surface water. Water entering Geogenous peatlands has absorbed dissolved nutrients as it moved over and through soil and bedrock. Geogenous peatlands are also called Mineotrophic, or mineral rich, peatlands because the moving water dilutes and removes acids and other metabolic by-products. Ombiogenous, or rain-originating, peatlands receive their water from precipitation and therefore do not receive the additional nutrients from the soil. These peatlands do not have water fluctuating in and out of the peatland, so they are more acidic. Lastly there are Oligotrophic, nutrient poor, or transitional peatlands and Eutrophic, nutrient rich, peatlands. These peatlands typically have some groundwater or surface water influence and their position in the landscape and type of vegetation influence the nutrient availability. Mitsch and Gosselink (2000) define bogs as peatlands that possess the following characteristics: a dominance of moss vegetation (specifically Sphagnum), a hydrologic input dominated by precipitation, a soil composition dominated by peat, and an acidic ph and high nutrient availability. While the term bog has been used as a general wetland term, today when the term bog is used by the ecological community it is used to refer to Ombiogenous peatlands. Mineotrophic, Oligotrophic and Eutrophic peatlands are most commonly referred to as fens and a nutrient modifier is placed in front of the word, such as nutrient rich fen (Johnson 1985). 12

13 Classification of peatlands can also be based on landscape position, a classification that can visually be determined but also provides much more ecological information than its position within the landscape. The terms used are level, slopped and raised. Raised peatlands are usually bogs and therefore do not receive groundwater input, instead they rely on precipitation. Sloped peatlands can be bogs or fens and level peatlands are typically fens (Johnson 1985). Fens are comprised predominantly of grass and sedge communities, have a hydrologic input of groundwater, contain mineral soil, have a neutral ph, and a moderate mineral availability (Mitsch & Gosselink, 2000). The driving factor impacting characteristics such as soil composition, plant composition, chemistry, and nutrient availability is the hydrologic input and output. Fens receive water through surface runoff and groundwater recharge and do have a hydrologic output. s obtain their water through precipitation and runoff and do not have a significant source of output (Mitsch & Gosselink, 2000). In other words, bogs are defined as mineral-poor, acidic peatlands that are raised above the groundwater, and fens develop under the influence of mineral-rich ground or surface water (Crum & Planisek, 1988; Wilcox, Shedlock, & Hendrickson, 1986). For the study in question, data obtained on species composition and ph will be used to define the type of peatland that best defines the North Springfield (Crum & Planisek, 1988; Mitsch & Gosselink, 2000; Thompson & Sorenson, 2000). Influences of ph on Vegetation Composition Numerous studies have shown relationships between ph and vegetation (Hajkova, Hájek, & Apostolova, 2006; Tahvanainen, 2004; Wilcox et al., 1986). Hájková et al.(2006) found that water ph and vegetation distribution are significantly correlated in mires in Bulgaria and ph is loosely correlated with fen vegetation distribution. This information adds evidence that supports 13

14 the theory that ph is the main driving factor influencing bog vegetation. The study attributed the difference to the continual mineral input from groundwater in fens. This input shifts acidity to a neutral level (Hajkova et al., 2006). Other studies have looked at primary influences driving local environmental plant distribution (Hajkova et al., 2006; Mouser, Hession, Rizzo, & Gotelli, 2005; Siegel & Glaser, 1987; Sjörs, 1950; Tahvanainen, 2004; Wilcox et al., 1986). These studies have found significant relationships between water chemistry and plant community composition, where the most influential chemical variable on vegetation composition was ph (Goslee, Brooks, & Cole, 1997; Hajkova et al., 2006; Hájková & Hájek, 2003; Wilcox et al., 1986). Gunnarsson et al. (2000) studied the diversity and ph of a boreal mire (or peatland) after 50 years of natural development where the anthropogenic impact was low. In 1945 Sjörs completed a detailed vegetative study on the mire. The area and study design used by Sjörs in 1945 was repeated in 1995 by Gunnarsson et al. (2000). Analyzing the 1945 data, Gunnarrson s team found a positive relationship between species richness and ph, where the largest amount of variation was found among plots with high ph. In addition, they found that the overall species number dropped between 1945 and 1995, with the largest drop in species number found among plots with a ph of 5; an area that had the highest diversity in 1945 (Gunnarsson, Rydin, & Sjörs, 2000). One reason for these changes could in part be due to Sphagnum, as it is known to be a species that acidifies its environment (Kooijman & Bakker 1993 from Gunnarsson; Gorham & Schindler, 1984). Sphagnum acidifies its environment through the production of galacturonic acid. Galacturonic acid, the molecule responsible for cation exchange, is located in the cell walls of peat mosses. Galactronic acid consists of a galactose molecule, in which the main hydroxyl 14

15 group is oxidized to a carboxyl group. The carboxyl bond is weak, allowing an exchange process of the release of hydrogen ions and absorption of metal cations into the carboxyl group in the galactose molecule. Through this process a buildup of H + ions occurs, creating an acidic environment (McQueen 1990). Studies have shown a correlation between galacturonic acid content and a Sphagnum species height above water level. Species growing near the tops of hummocks tend to have greater galacturonic acid content than species growing near the water level. Based on this information a description of a ph gradient can be assumed based on the plant s height above water level. On average plants near the water table will have a more neutral ph (7) than plants farther from the water table which will be more acidic approaching a ph of 1. Due of fluctuations in precipitation throughout the season, ph habitat for individual species can vary as much as 1 ph with the lowest ph values of Sphagnum-dominated wetlands occurring most often in the summer. Statements of fluctuations in wetland acidity can be assumed if one portion of the wetland is dominated by a more acidic Sphagnum, such as S. capillifolium versus a less acidic species such as S. squarrisum (see Table 1) (McQueen 1990). Table 1. Ranges and means of ph for Sphagnum species from Maine, New Hampshire and Vermont. Measurements were obtained from Sphagnum-dominated peatlands over the course of several summers (McQueen 1990). Species ph Range Mean S. angustifolium S. capillifolium S. centrale S. curspidatum S. fallax S. fimbriatum S. flexuosum S. fuscum S. girgensohnii S. magellanicum S. majus S. papillosum S. pulchrum

16 S. riparium S. russowii S. squarrosum S. subsecundum S. subtile S. teres S. warnstorfii In addition, Sphagnum, due to its anaerobic environment and the process of decomposition, over time contributes to the increase in the accumulation of peat, also known as paludification (Crum & Planisek, 1988). environments largely composed of Sphagnum rely on minerals from precipitation. In addition to the small input of minerals there is an increase of organic material as a result of slow decomposition created by the anaerobic environment. This is important because peat has a decreased ability to absorb and exchange cations. When all of these factors are placed together the bog environment becomes dominated by hydrogen ions, thus causing the ph to drop sharply (Mitsch & Gosselink, 2000). For centuries scientists have used ph levels within peatlands as defining classification elements (Crum & Planisek, 1988; Mitsch & Gosselink, 2000; Sjörs, 1950; Thompson & Sorenson, 2000). Scientists know that plants function within specified ph ranges, by studying species composition and their given ph range scientists can use ph as a means to classify peatlands (see Table 2). While there is an overlap of ph ranges and vegetation composition, it has also been well documented that this range is narrow and the overlap is minimal in context of community composition. It is obvious that there are overlaps in ph ranges within various peatlands, as there are also a varying range of vegetation communities (Appendix 1) and hydrologic inputs and outputs that assist in defining peatland types. 16

17 Table 2. Peatland classification & ph ranges. Author Peatland ph Range Sjörs (1950) North Sweden Moss Extreme poor fens Transitional poor fens Intermediate fens Transitional rich fens over 8 Extreme rich fens Crum (1988) Upper Midwest, USA Poor fens Rich fens Thompson & Sorenson (2000) Vermont, USA Dwarf shrub bog Pitch pine woodland bog Poor fens Intermediate fens Rich fens When analyzing these communities it is important to understand that indicator species and associations are guides that are linked to water flow and chemistry within each of these vegetation communities; that being said there is continual evidence that ph is the largest driving factor in vegetation composition (Crum & Planisek, 1988; Sjörs, 1950). Sjörs (1950) looked at the availability of salt content and utilized that information to describe varying species composition with association to ranges in ph. Sjörs found that areas with low salt content (and therefore low conductivity) had low ph and that a combination of the two factors helped confine the vegetation to a more narrow range of peatland types; this was found to be especially true when defining types of fens. While Sjörs found associations with the same combinations of ph and salt contents, he also concluded that the salt contents appears to be less influential on vegetation composition than ph and that the limit, especially in the fen community, will be found most often where calcareous water meets non-calcareous water. Sjörs 17

18 concludes that soil conditions surrounding peatlands are complicated and this is compounded by the salt content and ph of the water influencing the soil conditions (Sjörs 1950). Gorham & Janssens (1992) did a comprehensive study of fen and bog complexes across North America in context of bryophyte cover and their corresponding ph gradient. The results of Gorham & Janssens research supported previous studies that had taken place in North Sweden, Nova Scotia and Norway. Gorham & Janssens results showed that there was a bimodal ph gradient between the bryophyte groups Sphagnaceae and Amblystegiaceae; in that Sphagnaceae were associated with bogs and Amblystegiaceae were associated with fens. They stated that transitional zones within North America might occur between 4.8 and 6.2 and believe that this transition zone can occur quickly and within a horizontal range as small as 200 m. Goeham & Janssens attribute the quick change due to the poor buffering capability of peatlands between 4.5 and 6.0, stating that substantial and rapid modifications in ph result from slight shifts in the balance of bicarbonate and organic acids (Gorham & Janssens 1992). Hydrology One of the largest factors affecting peatland ph that impacts vegetation patterns is water chemistry. Flow rate is believed to have an impact on the nutrient balance of fens, partially due to the small variation in surface ph (Cooper & Andrus, 1994). In bog water, Siegel & Glaser (1987) concluded that an increase in ph by two increments (e.g. 4-7) in a meter depth can be suitably explained by groundwater discharge. In another study, Siegel (1983) found that as little as a 10% input of groundwater could change the ph of a bog from 3.6 to 6.8. In context of peatland classification this is enough to change the peatland environment from an ombrotrophic bog to a minerotrophic rich fen. 18

19 Obviously with the shift in groundwater there is a response and shift in species composition and distribution. Since a deciding factor in defining an ombrotrophic bog is a predominant hydrologic input of precipitation, the input of groundwater is seen primarily in fens. succession characteristically transitions from a fen community to a bog community; however, in the Glaser et al. (1990) study they encountered a fen that followed the opposite successional path. The authors deduced that the shift was due to groundwater input decreasing the alkalinity, leading them to believe that peatlands might be more sensitive to changes in groundwater than has been implied by past studies (Glaser et al. 1990). A primary cause of alterations in groundwater input and output to a peatland is most likely a result of anthropogenic impacts. Threats ranging from removal to an introduction of invasive species already exist; knowing that peatlands are also sensitive to a change in groundwater adds another element of disturbance that can occur within this habitat. The North Springfield The theory of kettlebog development in Vermont is based on the idea that kettleholes were once occupied by ice blocks; the ice blocks were buried in glacial outwash following glacial retreat. The combination of the cold temperature of the slowly melting ice and the glacial outwash provided the moist soggy conditions necessary for paludification (Crum & Planisek, 1988). If the NSB developed like most bogs, the open body of water was slowly overtaken by vegetation typically found in fens. Over time as organic material accumulated and created a more impervious layer the water became more acidic, due to decomposition, bacteria, and a lack of freshwater input. With the switch to more acidic water, the fen vegetation wouldn t have been able to adapt and Sphagnum and other species adapted to acidic environments became the 19

20 dominant vegetation (Mitsch & Gosselink, 2000; Mouser et al., 2005; Thompson & Sorenson, 2000). The NSB is located in a depression surrounded by a maple/hemlock forest and the source of hydrologic input appears to be precipitation, as there are no visible inflows or outflows. If the NSB is truly a bog and has developed an impervious organic layer, there should be no hydrologic input of groundwater. At this time an assumption about the origins of hydrology are all that can be made. It is believed that through the study of the vegetation, ph and the local precipitation a better understanding of the influencing factors on the bog will help answer questions of hydrology and vegetation composition. Based on the setting of the NSB, the lack of evidence of outflow, and the moss community it is easy upon initial observation to classify the peatland as a bog; however due to various fen and freshwater species seen, it is likely that based on a detailed mapping of species assemblages and ph data obtained within those communities, this information will provide strong reasoning that the NSB is not a bog and instead is a different type of peatland or a transitional peatland. If a detailed study finds this to be true, this information will help to reclassify the bog, and will provide data useful to other possible studies as the why this bog is developing the way it is. It is hypothesized that the data collected during this study will provide strong correlations between community assemblages and ph and this information will be correlated to the fluctuation of hydrology within each of those communities based on hydraulic flux within the community assemblages and the local weather data. If this study shows the possibility that the hydrology of the bog is not primarily precipitation, it will provide data that could be used for other studies to reduce the variability of other possible influencing factors. Minimally the information gathered from this study will provide additional data and information 20

21 about bogs of Vermont, specifically the NSB, and when this information is used by the Mount Ascutney Audubon Society it will help provide more detailed and accurate information to the public about the North Springfield. Perhaps the information obtained during this study will spark an interest in this bog and will encourage others to study it further. Goals & Objectives The goal of this study is to more accurately classify what is currently called the North Springfield. Through the mapping of the vegetation found within the North Springfield and the collection of ph data within communities and supporting precipitation data, it may be possible to make correlations of the vegetation response found at the NSB and to link this information to ph and/or hydrologic input. Due to the variability in the community structure of the NSB, it is anticipated that the results of the study will show a large difference in ph among the vegetation communities (as much as one to two values) and that these differences might be explained by a hydrologic input that is not confined to precipitation. The objectives of this study are: 1) Sampling and mapping the distinct plant communities in the North Springfield bog 2) Quantifying the ph of the three distinct plant communities in the NSB and 3) Monitoring water fluctuation in the three distinct plant communities. I hypothesize that correlations will exist between the current vegetation, ph and hydrology of the NSB to provide a hypothesis about contributing factors to plant distribution and composition; however this study will not attempt to prove causation. 21

22 METHODS Site Description The North Springfield is located on property owned by the Town of Springfield, VT in Windsor County in Springfield, VT. The bog is owned by the town of Springfield, VT but has entrusted the Ascutney Mountain Audubon Society to be stewards of the bog. The 0.4 acre bog is located west of the Black River at geographic coordinates W, , at feet above sea level. The bog consists of three community types: a moss community, a heath/shrub community, and a sedge community and is surrounded by a maple/hemlock forest (Figure 1). Vegetation analyses The location and extent of the three different community types was established in May 2007, based on visible observation of community grouping at the North Springfield (Crum & Planisek, 1988; Thompson & Sorenson, 2000). Vegetation composition was assessed in the summer field season of Random plots were chosen based on a random numbers table, the plots were then located on a map (to scale) of the NSB. Fifty-three random sample plots were sampled and 47 species were identified. Samples were collected until each community leveled off using the species-sample curve by plotting the cumulative number of species against the cumulative number of samples in each community (Brower et al, 1997). Vegetation composition was analyzed within a 1m 2 quad. Within the quad, species rooted within the quad were identified and a value of percent cover for each species, by strata, was determined. Trees with a DBH <3 were categorized as shrubs. Shrubs were assessed for percent aerial cover within the 22

23 1m 2 quad. Herbaceous vegetation rooted within the 1m 2 quad but occurring on decomposing logs was assessed. Figure 1. North Springfield, Springfield, VT June Vaccinium corymbosa (High bush blueberry), Photinia melanocarpa (Chokeberry) dominate the background, while Sphagnum, Sarraceniaceae purpurea (pitcher plant), Chamaedaphne calyculata (leather leaf), and Andromeda polifolia (bog rosemary) surround the boardwalk. ph and hydrology analyses Within each of the three communities demarcated by the vegetation analyses, one data box containing one Campbell Scientific CR10 modular datalogger, one Campbell Scientific Pressure Transducer, and one Campbell Scientific CSIM11-L Innovative Sensors ph probe with temperature compensation were installed. The boxes were placed approximately 5 feet from the edge of the bog and the cables containing the pressure transducer and ph probe were placed within 6 inches of the root mass found at the center of the community (Jeglum, 1971; Mouser, Hession, Rizzo, & Gotelli, 2005; C. J. ter Braak & Wiertz, 1994). It was anticipated that the ph near a root mass of one plant within a community would not differ significantly in ph value and 23

24 would therefore be a representative ph for the community. This is supported through a literature review of ph ranges for each specific type of vegetation found. ph and pressure transducer data from each of the community types were collected once a day at noon, from May 2, 2007 to October 3, 2007 for a total of 154 record days. In addition to the data boxes placed within each community, a fourth data box was placed in an open water area of the bog at a depth of 6 from the surface to determine hydrologic flux and ph data that are not directly influenced by vegetation. Data were downloaded biweekly on average utilizing a Campbell Scientific SC532 interface and was viewed in Campbell Scientific LoggerNet ver. 2.1 software. A break in data is found for dates falling between 6/29 to 7/16 and 9/16 to 10/3 due to battery loss. To establish if the ph probes within each community were representative ph readings of that community; independent ph readings were recorded at random points within each community. Initial readings were done using a Vernier LabPro with ph Sensor ph_bta interface with a Texas Instrument TI-83 Plus Graphing Calculator with Datamate v software. This equipment proved unreliable so the remainder of the readings were taken using a YSI 556MPS meter. Due to equipment failure and unreliable readings due to long reading time and water disturbance, these data were not analyzed. A stage meter marker in six inch increments was placed at the edge of the bog to determine surface hydrologic fluctuation. Stage readings were recorded each time data were downloaded from the community boxes. In addition to this hydrologic data, data were obtained from WeatherUnderground.com from the Hartness State Airport in, Springfield, VT. Weather records were obtained for May to October, Data obtained were the average daily precipitation and the mean daily temperature. 24

25 Data analysis Hydrographs were created using the hydrologic data recovered from the data loggers and the data collected from the airport. Statistical analysis was done using SAS system for Windows (SAS Institute 2000). All data were tested for normality. ph data were analyzed using a oneway ANOVA to assess variation among communities. Data were analyzed for possible relationships among ph, hydrology, and temperature for each vegetation community using Regression statistics. A Spearman Rank Test was performed with non-normal data (ter Braak, 1986). The sedge and shrub community data for hydrologic fluctuation were transformed using a log (10) transformation. 25

26 RESULTS Three distinct community types were identified along with an open water area; communities present were a shrub community, a moss community and a sedge community. The shrub community was dominated by Vaccinium corymbosa (highbush blueberry), Sphagnum cuspidatum, algae, and Ilex verticillata (common winterberry) with a mean ph of 5.37(Table 3). The moss community was dominated by Sphagnum cuspidatum, Sarraceniaceae purpurea (pitcher plant), Andromeda polifolia (bog rosemary) and Chamaedaphne calyculata (leather leaf), with a mean ph of The open water area was dominated by Vaccinium corymbosa, algae, Sphagnum cuspidatum, and Pontederia cordata (pickerl weed), with a mean ph of The Sedge community was dominated by Pontederia cordata and Carex Interior, with a ph of The mean ph for the entire bog community was The dominant bog species is Sphagnum cuspidatum with a total cover of 23.35%, followed closely by Vaccinium corymbosum 13.62%, Pontederia cordata 9.98%, and Carex interior 4.09% (Appendix 4). Table 3. Community dominance, wetland classification, and ph range Species Community Wetland Classification ph Range Vaccinium corymbosa Shrub, Open Black Spruce Woodland, Pitch Pine Woodland, Sphagnum cuspidatum Shrub, Moss, Poor Fen Open Algae Shrub, Open Ilex verticillata Shrub Black Spruce Woodland Sarraceniaceae purpurea Moss, Drawf Shrub, Black Spruce Woodland, Poor Fen, Rich Fen Andromeda polifolia Moss, Poor Fen, Rich Fen, Intermediate Fen Chamaedaphne calyculata Moss, Spring Fen, Intermediate Fen, Pontederia cordata Open, Sedge Freshwater Wetlands Carex Interior Sedge, Poor Fen, Rich Fen, Spring Fen, Intermediate Fen McQueen (1990) 1 ; USDA, NRCS. (2007) 2 26

27 A significant difference in ph (one-way ANOVA F 3, 552 =478, p <0.0001, Tukey, p <0.05) was found for each community type (Figure 2). There was a correlation between precipitation and fluctuation in the Open (n = 153, r = 0.217), Sedge (n=120, r= 0.228), Shrub (n = 133,r = 0.180), and on the average of all communities (n=154, r = 0.045). While a correlation was found in these communities, the r value was very low, and due to the sensitivity of the Spearman Rank Correlation to sample size a true correlation is questionable. Each community demonstrated a positive correlation; however the r 2 values were low with the highest correlation in the sedge community (r 2 = 0.506,p <0.0001). A positive correlation was found in all communities but again, the r 2 values were low, with the greatest correlation appearing in the shrub community (r 2 = 0.265,p <0.0001) ph Open Moss Sedge Shrub Total Area Community Figure 2. Means of ph by community. Bars represent standard deviation. A significant difference was found among each of the community types, with all community combinations. 27

28 ph ph Open ph Pitcher ph Sedge ph Shrub /2/2007 5/16/2007 5/30/2007 6/13/2007 6/27/2007 7/11/2007 7/25/2007 Date 8/8/2007 8/22/2007 9/5/2007 9/19/ /3/2007 Figure 3. ph distribution among the varying communities. The solid line on July 11, 2007 represents the fall of the Acer rubrum on the sedge community. 28

29 Depth (in.) Precipitation Open Moss Sedge Shrub /2/07 5/9/07 5/16/07 5/23/07 5/30/07 6/6/07 6/13/07 6/20/07 6/27/07 7/4/07 7/11/07 7/18/07 7/25/07 Date 8/1/07 8/8/07 8/15/07 8/22/07 8/29/07 9/5/07 9/12/07 9/19/07 9/26/07 10/3/07 Figure 4. Community hydrologic fluctuation data combined with precipitation records from the Hartness State Airport in, Springfield, VT. 29

30 DISCUSSION The NSB is complex on many different levels. Most individuals with knowledge of Northeastern bogs imagine short carpets of spongy vegetation dominated by Sphagnum, Pitcher Plants, Cranberries, and Sun Dews with heath shrubs along the edge. The NSB does not fit this image. Instead the NSB appears to be dominated by shrubs (Figure 1). Sampling shows that the dominant bog species in order of dominance to be Sphagnum cuspidatum, Vaccinium corymbosum, Pontederia cordata and Carex interior. While Sphagnum cuspidatum, and Vaccinium corymbosum have an acidic ph and are commonly found in bogs and fens, Pontederia cordata and Carex interior have a slightly acidic to basic ph and are found more commonly in freshwater wetlands. Studies have continually provided evidence that ph is the largest driving factor in vegetation composition (Crum & Planisek, 1988; Sjörs, 1950). Scientists have depended on this correlation as a defining element with which to classify peatlands (Crum & Planisek, 1988; Mitsch & Gosselink, 2000; Sjörs, 1950; Thompson & Sorenson, 2000). While it has been shown that an overlap of ph ranges and vegetation composition, it is well documented that the range and overlap is minimal. This is evident in the NSB as well, comparing the species dominance range with an overall mean ph of 4.94 (Table 3). Comparing the species dominance with the ph ranges found for each plant and the wetland classification that is typically found with each of these plants, one can see that the NSB aligns more closely with the Fen classification as five of the nine dominate species fit within the wetland classification and ph range found in Fens (Table 3). 30

31 Aside from ph and vegetation composition the other underlying factor in differentiating a fen and a bog is the hydrologic input and output. s are defined as having a hydrologic input dominated by precipitation and no outflow, while a fen has an inflow and outflow. Viewing the hydrologic fluctuation and precipitation it is evident that there is a pattern in hydrologic fluctuation and precipitation; however based on this information there is nothing that implies there is a change in hydrology that can not be explained by precipitation and transpiration (Figure 4). The data analysis of ph showed a significant difference among each community type. Small correlations were found between ph and hydrologic fluctuation and ph and temperature. These data support what has been documented in other studies -- that while other factors play a role in community composition, ph is the strongest corollary to species composition. Studies documented by Gorham & Schindler (1984) show a peatland transition zone occurring between due to poor buffering capabilities. During this transition period less acidic species are succeeded by more acidic species, following typical bog succession. While bog succession typically transitions from a fen community to a bog community there have been documented sites where the transition was reversed (Glaser et al. 1990). Small amounts of literature and individual field observations of vegetative composition of the NSB imply that the NSB has typically been composed of bog species. One possible explanation for the atypical species composition and dominance is because the bog is in a period of transition. While I believe it is possible that the NSB is in a period of transition, I also believe that there are several anthropogenic and environmental factors affecting species composition and distribution. The Ascutney Mountain Audubon Society has been stewards of the bog for 31

32 at least a decade and during that time the bog has been severely impacted. One of the first acts of the Ascutney Mountain Audubon Society was to place a floating boardwalk within the NSB to allow the public access to the bog and its beauty. Before the boardwalk could be put in place large amounts of trash were removed from the bog, including a car. Obviously evidence suggests that the site was used as a dump at one point in time. As stated previously paludification occurs, due to the anaerobic environment and the process of decomposition of Sphagnum (Crum & Planisek, 1988). In typical bog succession, paludification would continue to occur over time creating thicker mats of peat. Due to the forces necessary to remove large amounts of debris from the bog, it is also logical to assume that large amounts of peat were disturbed during that process. This removal could have severely impacted the peat layer allowing less acidic plants to take hold due to a shift in ph and a possible introduction of minerals. Since the initial clean-up the Ascutney Mountain Audubon Society has an annual clean up that helps keep the bog free of litter. One of the largest draws of the NSB is the Sarraceniaceae purpurea, the beautiful carnivorous pitcher plant. Sarraceniaceae purpurea is most dense along the edge of the boardwalk and in order to keep the boardwalk passable and to allow a view of the pitcher plant, the shrubbery is trimmed, and unwanted seedlings are removed (e.g., white pine and red maple). Trimming of the shrubbery and removal of unwanted seedlings is obviously changing the environment surrounding the boardwalk. A greater amount of sunlight is able to reach the plants and competition is kept at a minimum. In addition to the anthropogenic impacts at the NSB, there are several environmental factors influencing species composition. Sphagnum is still a dominating force within the NSB so one can not overlook the acidifying affect of Sphagnum. Additionally one has to remember that 32

33 the bog is relatively small in size, so edge effect plays a large role in species composition. The edge of the bog is the first to receive runoff, which is higher in minerals such as Calcium and Magnesium (Karlin & Bliss 1984). This influx of minerals impacts the buffering capability of the bog, creating a less acidic environment which could explain the dominance of Vaccinium corymbosa Pontederia cordata, Carex interior, and Carex lurida around the edge of the bog. In addition to the influence of minerals along the edge of the bog, the NSB varies markedly from the Northwest side to the Northeastern side. The Northwestern side of the bog upland is dominated by a white and red pine overstory. Field observation revealed that the Northwestern corner of the bog is covered with pine needles approximately 4 inches deep. It has been shown that the acid in the needles of the pine can leach into the water and increase the acidity of the water (P.H. 2003). In this area there are less Sphagnum species and the area is dominated by Pontederia cordata, Carex interior and Carex flava near the edge of the bog and around 3m from the edge of the bog the area is dominated by the shrub community. Within the shrub community another microcosm of communities exists. The shrubs are raised up approximately two feet from the surface water of the bog, and the larger the stand of shrubs the more complex the microcommunity appears. Within large stands the understory growing on the trunks of the shrubs are dominated by what appear to be fresh water mosses, and Triadenum virginicum. Still within the shrub hummock/tussocks are Matteuccia struthiopteris and Picea mariana, while the hollows are dominated by the submerged Sphagnum cuspidatum. The Northeastern side of the bog is also dominated by shrubs but there is a greater amount of open water and the overstory is more open and composed primarily of Acer rubrum., The Southern side of the bog is dominated by Pontederia cordata, with Sphagnum cuspidatum near the upland edge of the bog. In this area there is still a blanketing of white and red pine needles 33

34 but they are not nearly as thick. Instead this area is more heavily impacted by decomposing logs, which tend to be covered with freshwater mosses and herbs. In the Southwestern corner of the bog, approximately 3m toward the center of the bog, the area is dominated by Pontederia cordata, Carex interior and Carex lurida. This community is a floating mat, ~ 3 thick of sedges and very few Sphagnum spp. or shrubs. This community is small and only ~ 4m deep by 10m wide. Not only is the sedge community on the Southwestern side of the bog small it is also tenuous. This area appears to be the most susceptible to fallen trees. The Southwestern corner is surrounded by two large (approximately 3-4ft DBH) and decomposing Acer rubrum. During the vegetation analysis, three trunks approximately 1ft DBH each fell over the sedge community, covering and sinking approximately 80% of the community. It is evident from these data that ph is greatly impacted from such disturbances and could have dramatic impacts on vegetation composition (Figure 3). As one moves Northeast toward the center of the bog the community switches to a shrub community dominated by Vacinnium corymbosum. This shrub community exhibits the same hummock heights and microcommunities as are those seen on the Northwestern side of the bog. The vegetation found near the center of the bog, and closest to the trimmed edge of the boardwalk is dominated by Sphagnum in hummocks and hollows, Sarraceniaceae purpurea, Chamaedaphne canadense, and Andromeda polifolia. 34

35 CONCLUSION So is this bog in transition? It is very possible that the NSB is transitioning or has transitioned to a community composition and mean ph that, aside from evidence of hydrologic output or groundwater influx, fits the description of a Poor Fen. To be more definitive in this assumption a closer and more invasive analysis of the groundwater in and around the NSB should be assessed along with the collection of detailed vegetation composition over time. What does it mean if the NSB is a fen? Does this new information change anything? The purpose of labeling a wetland a freshwater marsh, tidal marsh, bog or fen is that the definitions provide an insight into the vegetation and chemistry one could expect based on these labels. Relabeling the North Springfield a fen would characterize the peatland within the proper vegetation and ph classification. This information provides insight into the type of vegetation one could expect at the site, the chemistry within the peatland and information about the aquatic environment. I do not believe that relabeling the NSB is necessary; however, I think it would be beneficial to the public and the school children that visit the area to be informed as to the unique characteristics of the bog and factors that contribute to its makeup such that it fits the definition of a fen. I think it would be beneficial for the Ascutney Mountain Audubon Society and the school children that regularly access the bog to make observations about vegetation changes over time. It would also be interesting to see what would happen if an area of the boardwalk was to remain untrimmed -- would the pitcher plants still continue to thrive? Over time would we see a bog that is transitioning more and more into a fen, or would we see a bog that s recovering from 35

36 a major disturbance from 15 years ago? I think additional data collection would benefit the Ascutney Mountain Audubon Society and contribute to the larger understanding of bogs in Vermont, the impacts of disturbance on a bog, and the impacts of edge effect. I would also recommend a peat core analysis. A peat core could provide insight about the age of the peat, if there was a disturbance in the peat at one point in time, and would show changes in community composition. I do not believe that the Ascutney Mountain Audubon Society will allow the Sarraceniaceae purpurea to be overshadowed by shrubs and will continue to manage the area. However, I think that the NSB is a very interesting peatland with so much information to offer. Not everything happening at the NSB can be seen with the naked eye or is it as showy as the beautiful pitcher plant; instead the NSB is a large mystery waiting to unfold through patient observations and continued data collection. 36

37 REFERENCES Brower, J., Zar, J., & von Ende, C. (1997). Field and laboratory methods for general ecology (4th ed.). United States of America: WCB McGraw-Hill. Cooper, D., & Andrus, R. (1994). Patterns of vegetation and water chemistry in peatlands of the west-central wind river range, wyoming, U.S.A. Canadian Journal of Botany, 72, Crum, H., & Planisek, S. (1988). In Douglas M. (Ed.), A focus on peatlands and peat mosses. Ann Arbor, Michigan: The University of Michigan Press. Glaser, P. H., Janssens, J. A., & Siegel, D. I. (1990). The response of vegetation to chemical and hydrological gradients in the lost river peatland, northern minnesota. Journal of Ecology, 78(4), Gorham, E., & Janssens, J. A. (1992). Concept of fen and bog re-examined in relation to bryophyte cover & the acidity of surface water. Acta Societatis Botanicorum Poloniae, 61, Gorham, E., & Schindler, D. (1984). Ecological effects of acid deposition upon peatlands; a neglected field in "acid-rain" research. Canadian Journal of Fisheries & Aquatic Sciences, 41, Goslee, S., Brooks, R., & Cole, C. (1997). Plants as indicators of wetland water source. Plant Ecology, 131,

38 Gunnarsson, U., Rydin, H., & Sjörs, H. (2000). Diversity and ph changes after 50 years on the boreal mire skattlösbergs stormosse, central sweden. Journal of Vegetation Science, 11, Hájková, P., & Hájek, M. (2003). Species richness and above-ground biomass of poor and calcareous spring fens in the flysch west carpathians, and their relationships to water and soil chemistry. Preslia, 75, Hajkova, P., Hájek, M., & Apostolova, I. (2006). Diversity of wetland vegetation in the bulfarian high mountains, main gradients and context-dependence of the ph role. Plant Ecology, 184, Jeglum, J. (1971). Plant indicators of ph and water level in peatlands at candle lake, saskatchewan. Canadian Journal of Botany, 49, Johnson, C. (1985). s of the northeast. Hanover, NH: University Press of New England. Karlin, E.F., & Bliss,L.C. (1984) Variation in substrate chemistry along microtopographical and water-chemistry gradients in peatlands. Canadian Journal of Botany, 61, Lichvar, R. W. (2007). Floristic survey of the vascular flora of the North Springfield bog, North Springfield, VT. Unpublished manuscript. Mandossian, A. (1966). Variations in the leaf of Sarracenia purpurea (Pitcher Plant). The Michigan Botanist 5, McCune, B., & Grace, J. (2002). Analysis of ecological communities. Gleneden Beach, OR: MjM Software Design. 38

39 McQueen, C. (1990). Field guide to the peat mosses of boreal north america. Hanover NH: University Press of New England. Mitsch, W., & Gosselink, J. (2000). Wetlands (Third Edition ed.). New York, NY: John Wiley & Sons, Inc. Mouser, P. J., Hession, W. C., Rizzo, D. M., & Gotelli, N. J. (2005). Hydrology and geostatistics of a vermont, USA kettlehole peatland. Journal of Hydrology, 301(1-4), P.H Back to a bog. Environment45, (2), 4 SAS Institute Inc. (2000) SAS/STAT User s Guide. Verion 6. SAS Institute Inc., Cary, NC, USA. Siegel, D.I. (1983). Ground water and the evolution of patterned mires, glacial Lake Agassiz peatlands, Northern Minnesots. Journal of Ecology, 71, Siegel, D. I., & Glaser, P. H. (1987). Groundwater flow in a bog-fen complex, lost river peatland, northern minnesota. Journal of Ecology, 75(3), 743. Sjörs, H. (1950). On the relation between vegetation and electrolytes in north swedish mire waters. Oikos, 2(2), Tahvanainen, T. (2004). Water chemistry of mires in relation to the poor-rich vegetation gradient and contrasting geochemical zones of the north-eastern fennoscandian shield. Folia Geobotanica, 39,