Assessment of Prairie Restoration and Vegetation Change at the Buffalo Beats Research

Natural Area, Athens County, OH

A thesis presented to

the faculty of

the College of Arts and Sciences of Ohio University

In partial fulfillment

of the requirements for the degree of

Master of Science

Corey K. Kapolka

May 2014

This thesis titled

Assessment of Prairie Restoration and Community Change at the Buffalo Beats Research

Natural Area, Athens County, OH

COREY K. KAPOLKA

has been approved for

the Department of Environmental and Plant Biology

and the College of Arts and Sciences by

Brian C. McCarthy

Professor of Environmental and Plant Biology

Robert Frank

Dean, College of Arts and Sciences

ABSTRACT

KAPOLKA, COREY K., M.S., May 2014, Plant Biology

Assessment of Prairie Restoration and Community Change at the Buffalo Beats Research

Natural Area, Athens County, OH

Director of Thesis: Brian C. McCarthy

The regionally rare remnant prairie ‘Buffalo Beats’ has been managed with a controlled burn regime since evidence of forest encroachment in the 1980’s prompted restoration efforts. Comparisons of vegetation samples from the prairie from 1984 and

2012 show an increase in diversity of non-prairie species, a stabilization of frequency and vegetative cover of prairie species, and a decrease in the community importance of woody species. Within the surrounding forest, abundance of small trees decreased, total tree DBH increased, and the importance of Quercus alba increased among most size and age categories. Comparison by NMDS of the prairie community in 1986, 1996, and 2012 showed no apparent directional shift in community composition. The Buffalo Beats prairie has been effectively preserved by implementation of controlled fires and woody removal, and continued restoration efforts are likely necessary to preserve the community into the future.

ACKNOWLEDGEMENTS

The research presented here was made possible by the work and assistance of the

Wayne National Forest, Athens Unit, and Forest Service Botanist Cheryl R. Coon. I am grateful for the abundant advice offered by my advisor, Dr. Brian C. McCarthy, as well as from Dr. Harvey E. Ballard and Dr. Jared L. DeForest, all of whom served as members of my thesis committee. My research was also improved from conversations with Dr.

Alex A. Anning, Stephen J. Murphy, and Joseph Moosbrugger. Historical information and data from previous work at Buffalo Beats were provided by E. Dennis Hardin. This research was funded by a Small Research Grant provided by the Ohio Natural History

Survey and by the Ohio University Department of Environmental and Plant Biology.

TABLE OF CONTENTS

Page Abstract ...... 3 Acknowledgments...... 4 List of Tables ...... 6 List of Figures ...... 8 Introduction ...... 10 Buffalo Beats Research Natural Area ...... 14 Methods...... 22 Statistical Methods ...... 26 Results ...... 27 Prairie Community ...... 27 Southern Lens ...... 35 Shrubs and Vines ...... 38 Seedlings, Saplings, and Trees...... 39 Soil Conditions...... 46 Soil Seedbank...... 52 Discussion ...... 55 Prairie Community ...... 55 Southern Lens ...... 58 Forest Community ...... 59 Soil Conditions...... 62 Soil Seedbank...... 63 Conclusions ...... 65 References ...... 68 Appendix ...... 75

LIST OF TABLES

Page

Table 1. Timeline of publications and reports referring to Buffalo Beats, as well as important management events at or concerning the site ...... 15

Table 2. Plant species identified in Buffalo Beats prairie during biweekly floristic surveys from March through October 2012 ...... 30

Table 3. Herbaceous and graminoid species mean vegetative cover and plot frequency within prairie, transition, and forest zones at Buffalo Beats Research Natural Area in September 2012...... 31

Table 4. Importance values (IV) for plant species present within permanent plots of the Buffalo Beats prairie during sampling in the late summers of 1986, 1996, and 2012 ...... 34

Table 5. Herbaceous and graminoid species mean vegetative cover and plot frequency within permanent plots in the 'southern lens' habitat at Buffalo Beats Research Natural Area in September 2012 ...... 36

Table 6. Shrub and vine species mean vegetative cover and plot frequency within the southern lens community at Buffalo Beats Research Natural Area in September 2012 ...... 37

Table 7. Shrub and vine species mean vegetative cover and plot frequency within prairie, transition, and forest zones at Buffalo Beats Research Natural Area in September 2012 ...... 37

Table 8. Seedling cover and frequency of tree species observed in permanent plots of the northern prairie and southern lens of Buffalo Beats RNA in September 2012 ...... 39

Table 9. Density and frequency of tree seedlings and saplings (DBH < 2.5cm) and density (D) and basal area (BA) of mature trees per ha, and frequency (F) and importance values (IV) of three diameter classes of mature trees (DBH > 2.5cm) within the transition zone of the Buffalo Beats Research Natural Area in September 2012...... 42

Table 10. Density and frequency of tree seedlings and saplings (DBH < 2.5cm) and density (D) and basal area (BA) of mature trees per ha, and frequency (F) and importance values (IV) of three diameter classes of mature trees (DBH > 2.5cm) within the forest zone of the Buffalo Beats Research Natural Area in

September 2012 ...... 43

Table 11. Total count and percent plot frequencies of germinated seedlings observed from seedbank samples gathered from herbaceous plots in the prairie, transition, forest, and southern lens zones at Buffalo Beats in March 2013 ...... 50

Table 12. Total count and percent plot frequencies of germinated seedlings observed from seedbank samples gathered from herbaceous plots in the prairie, transition, forest, and southern lens zones at Buffalo Beats in late May 2013 ...... 51

Table 13. Shorthand labels of plant species observed at Buffalo Beats during 50 years of study for use in graphical visualizations of community structures ...... 75

LIST OF FIGURES

Page

Figure 1. Buffalo Beats prairie. Photograph taken by the author facing north on August 23, 2012 ...... 16

Figure 2. Area where trees were girdled on the southern clay lens of Buffalo Beats. Visible understory vegetation is dominated by populations of Rubus spp. Photograph taken by the author on March 27, 2012 ...... 21

Figure 3. Aerial photographs of Buffalo Beats RNA and diagrams of plots sampled: A) Buffalo Beats RNA; B) Southern lens with herbaceous plot transect; C) Northern prairie; D) Plot transects with locations of 10 × 10m plots and nested 2 × 10m plots, and herbaceous plots represented with black rectangles. Aerial images obtained through Google Maps on 9 February 2014 ...... 23

Figure 4. Four 'prairie species' (Cusick and Troutman 1978) not previously documented at Buffalo Beats. Clockwise from top left: Monarda fistulosa, Sabatia angularis, Phlox pilosa, and Sisyrinchium albidum. Photographs taken by the author during the summer of 2012 ...... 28

Figure 5. Box plot of pH values of soils sampled from the prairie, transition, forest, and southern lens zones of the Buffalo Beats Research Natural Area in 2013. Boxes represent the interquartile range of values between the first and third quartiles of pH values, lines representing median values contained within them. Whiskers extend to maximum and minimum values. No significant differences were observed among the pH values of soils from the sampled locations (P > 0.05) ...... 45

Figure 6. Box plot of carbon to nitrogen ratios of soils from the prairie, transition, forest, and southern lens zones of the Buffalo Beats Research Natural Area in 2013. Boxes represent the interquartile range of values between the first and third quartiles of pH values, lines representing median values contained within them. Whiskers extend to maximum and minimum values. Differences among letters above each bar indicate significant differences among mean C:N ratios (P < 0.05) ...... 45

Figure 7. Mean percentage of sand, silt, and clay of A horizon soils of the southern lens habitat of Buffalo Beats RNA. Error bars indicate 95% confidence intervals of the mean of each particle type ...... 46

Figure 8. Three-dimensional NMDS of plant community composition of the prairie, transition, and forest zones of Buffalo Beats RNA in September 2012.

Plot grouping is shown in A and C, with labeled ellipses indicating 95% CI of each group. Green, blue, and red diamonds indicate prairie, transition, and forest plots, respectively. Associated species data are shown in B and D. Acronyms represent the first two letters of the genus and specific epithet, respectively. Full species names provided in Table 13 ...... 48

Figure 9. Three-dimensional NMDS of plant community composition of the prairie of Buffalo Beats RNA in the late summers of 1986, 1996, and 2012. Plot grouping is shown in A and C, with labeled ellipses indicating 95% CI of each year group. Green, red, and blue diamonds indicate 1986, 1996, and 2012 plots, respectively. Associated species data are presented in B and D. Acronyms represent the first two letters of the genus and specific epithet, respectively. Full species names provided in Table 13 ...... 49

INTRODUCTION

The plant communities of North American prairies have persisted since the

Tertiary Period (25 MYA; Weaver 1954), and developed as a result of the growth of the

Rocky Mountains and the blockage of moist air from dispersing into areas east of the mountain range. The drying of the climate in this region, stretching from Texas into

Saskatchewan and east into Illinois, resulted in the development of plant communities tolerant of xeric conditions, which largely included grasses and forbs to the exclusion of tree species (Gleason 1952). The expansive grasslands, or ‘prairie,’ have occupied fluctuating areas as glacial advances and warming periods removed available land and expanded suitable locations over time. During a particularly warm recent period (8,000-

5,000 YBP), termed the ‘xerothermic period,’ prairie extended east into Michigan,

Indiana, and Ohio, where remnants of the ‘prairie peninsula’ can still be found (Transeau

1935).

Early American settlers of the region took advantage of the rich soils that developed under the prairie, and cleared natural communities to establish expansive agricultural fields. Estimates of the natural prairie now remaining following anthropogenic change are from 1% to 3% (Smith 1990, 2000), making the prairie among the most highly devastated natural communities in North America (Smith et al. 2010).

Where settlers saw a wide expanse of uniformity in the Great Plain, an immense diversity across the grasslands went largely unappreciated until ecologists began studying prairie communities. In a massive undertaking by Weaver and his students, prairie species lists for individual Great Plains states counted well over 200 species, and hundreds more

11 species were found to occupy less than ten percent of the 135 locations studied (Weaver and Fitzpatrick 1934). The layered structure of prairie communities and variety of regional communities allow for broad biological diversity that was unfortunately rapidly disappearing when it was finally recognized.

Prior to Transeau (1935), studies of the geographic extent of the prairie into the

East were not widely published in ecological literature. The remnants of prairie left from the xerothermic period are largely fragmented and surrounded by mixed deciduous forest, though numerous communities do exist in Indiana, Michigan, and Ohio. The meeting of the great prairie to the west with the dense forests of the east and north has resulted in a broad transition zone; a mosaic of prairie, savanna, and forest communities (Anderson and Bowles 1999). The distinction of savanna and prairie can be contentious and largely semantic, depending on the actual influence of trees on a given community. A savanna could be defined as a grassland with a high density of canopy trees (Nuzzo 1986); a grassland with less than 50% canopy closure (Curtis 1959); or a community with scattered trees present in an otherwise grassland ecosystem (Scholes and Archer 1997).

Regardless of how one chooses to distinguish individual community types along the continuum of potential assemblages of individual species, the prairie mosaic is undeniably important in the Eastern Midwest.

Ecotypic variation in grassland species has allowed most prairie species to persist in the eastern extent of the peninsula even following the cessation of the xerothermic period (McMillan 1959). The communities where grassland species now persist have integrated into a mosaic ecotone across several states in the eastern Midwest. Rohr and

Potzger (1952) noted a broad ecotone in Indiana, at the doorstep of the Great Plains, from prairie to savanna and woodland. Extending north, Veatch (1928) recognized the mark of the prairie peninsula was largely restricted to the southwestern corner of the lower peninsula of Michigan, but Butler (1995) located some 58 individual prairie sites, primarily in Kalamazoo, Cass, St. Joseph, and Branch counties. At the furthest eastern reaches of the peninsula, Transeau (1935) noted that all major grasses, a wide majority of lowland grasses and forbs, and around half of upland grass and forb species associated with prairies were found in Ohio. Extant prairie and savanna communities have been well-documented throughout the state, especially in areas around Toledo, Columbus, and

Adams County (Gordon 1969). These remnant communities likely only represent a fraction of the total area which grassland communities occupied in this region prior to modern settlement and associated anthropogenic changes.

Settlement of new territories as a young America expanded westward initially did not interrupt the dynamic natural cycles of grassland communities, though conversion of natural grasslands into agricultural fields did occur. Mixed forest and grassland landscapes, such as those found throughout Ohio, were attractive locations to arriving settlers who required lumber and open fields for use in agriculture (Jordan 1964). In the early 20th century, broad suppression of the occurrence and spread of natural fires throughout the United States further changed the remaining prairie communities by halting disturbance regimes that maintained natural plant communities. Disturbances such as fire frequently halted the encroachment of woody species into herbaceous communities, and woody species could freely invade vulnerable habitats without regular

13 fires. Though the initiation of well-intentioned fire prevention measures began merely a century ago, quality remnants of the former wide-reaching prairie peninsula are now exceedingly rare.

Prior to the wide settlement of its wild lands and the application of forest fire prevention programs, the landscapes of Ohio were dotted with small grassland communities mixed among dense deciduous forest. The reach of the prairie peninsula into Ohio from the Great Plains resulted in the formation of many kinds of prairie or

‘barrens’ communities noted by early settlers, from open xeric tallgrass prairie to sparsely wooded savanna and wet prairie (Heikens and Robertson 1994).

Remnant prairies within Ohio are scattered and few, though some large areas remain intact. A consortium of state agencies and private interests have been locating and

preserving such remnants since the mid-20th century, and have successfully organized

combined conservation efforts throughout the state (Ramey and Troutman 1976).

Remnants can be found throughout Ohio in cemeteries and rights-of-way that are largely untouched by human development (Cooperrider et al. 2001), in large preserves of prairie

and savanna such as the Oak Openings region of northern Ohio (Abella et al. 2001,

Brewer and Vankat 2004), and forest clearings persisting on soils unfavorable to woody species growth (Wistendahl 1975). Though these areas may be safe from development, a

lack of natural disturbance regimes will inevitably result in their loss by forest

encroachment. Management plans incorporating prescribed burning of fire-dependent communities have the potential to restore such communities to a pre-settlement condition,

and encourage the expansion of rare prairie plant species populations. By studying

14 changes in plant community composition of one such community under management of

the US Forest Service, I address here the effectiveness of prescribed fire and woody

removal in preserving and restoring an isolated prairie remnant in southeastern Ohio.

Buffalo Beats Research Natural Area

One remnant prairie community near the furthest extent of the former prairie peninsula is ‘Buffalo Beats,’ located within the Wayne National Forest in Athens County,

Ohio (39o 27' 18” N, 82o 4' 35” W). The site is a 'climate relict' or 'microrefugium' of the prairie peninsula of the xerothermic period (Hampe and Jump 2012, Dobrowski 2011), preserved atop a calcareous clay soil lens following the cooling of the regional climate.

The prairie had been owned by absentee landowners from the original issuance of a land deed until 1942, when it was acquired by the US Forest Service (Boyle and Ortt 1999).

The lack of active use of the land surrounding Buffalo Beats meant that anthropogenic change was not a direct factor at the site until the USFS began fire suppression efforts in the early 20th century.

A timeline of publications and unpublished reports referring to Buffalo Beats, as well as important events concerning the site is presented in Table 1. Buffalo Beats was first documented in the literature in a 1925 update to the vascular flora of Ohio by

Schaffner, who included herbarium samples from 'Buffalo Beat' submitted by Mr. Len

Stephenson. The vegetation of Buffalo Beats was first described in the literature in 1944

(Jones 1944), and permanent plots were initially sampled by Boyce in 1956 and later by

Wistendahl in 1962 (Wistendahl 1975). The site was mentioned in several minor

Table 1. Timeline of publications and reports referring to Buffalo Beats, as well as important management events at or concerning the site. Year Event 1925 'Additions to the catalog of Ohio vascular plants for 1924' (Schaffner 1925). First documentation of Buffalo Beats, reported as 'Buffalo Beat' by Len Stephenson. 1926 'Additions to the catalog of Ohio vascular plants for 1925' (Schaffner 1926). 1927 'Additions to the catalog of Ohio vascular plants for 1926' (Schaffner 1927). 1933 'Additions to the revised catalog of Ohio vascular plants' (Schaffner 1933). 1935 'The prairie peninsula' (Transeau 1935). 1942 Acquisition of the Buffalo Beats site by Wayne National Forest from absentee land owners. 1944 'Studies in Ohio floristics-III. Vegetation of Ohio prairies' (Jones 1944). 1956 'Notes on some unusual flora found in Athens County, Ohio' (Porter 1956). 1956 Establishment of permanent vegetative sample plots in Buffalo Beats prairie by S.A. Boyce. 1958 'Notes on the hepatic flora of the Athens area' (Hall 1958). 1975 'Buffalo Beats, a relict prairie within a southeastern Ohio forest' (Wistendahl 1975). 1978 The prairie survey project, a summary of data to date' (Cusick and Troutman 1978). 1981 'Buffalo Beats, a prairie remnant in unglaciated southeastern Ohio, supports Transeau's Prairie Peninsula concept' (Wistendahl 1981). 1983 'A proposal for designation as a Research Natural Area' submitted to USFS, Athens Unit by the Ohio chapter of The Nature Conservancy (Hirsh 1983). 1984 'Proposed ecological management plant for Buffalo Beats prairie, Athens Unit, Wayne National Forest' submitted by the Ohio chapter of The Nature Conservancy (Hardin 1984). 1985 'Recommendations for designation of special areas within the Wayne National Forest' submitted by the Ohio Department of Natural Resources, Division of Natural Areas & Preserves (Moseley 1985). 1986 Buffalo Beats recommended as a Candidate Research Natural Area by the Wayne National Forest RNA Evaluation Group (Boyle and Ortt 1999). 1987 (13 March) Controlled burn of Buffalo Beats (only the prairie community). 1988 'Succession in Buffalo Beats prairie and surrounding forest' (Hardin 1988). 1990 'Phytolith analysis of soils at Buffalo Beats, a small forest opening in southeastern Ohio' (Kalisz and Boettcher 1990). 1992 Buffalo Beats designated a Special Area by Amendment 7 to the Wayne National Forest Land and Resource Management Plan (Boyle and Ortt 1999). 1995 'Draft TNC Management Plant for Buffalo Beats' prepared by the Ohio Chapter of The Nature Conservancy (Sutherland 1995). 1995 'Establishment Report for Buffalo Beats: A Research Natural Area within Wayne National Forest, Athens County, Ohio' prepared by Ohio Department of Natural Resources, Division of Natural Areas & Preserves (Ortt 1995). 1996 (12 April) Controlled burn of Buffalo Beats (northern site). 1996 'Research Report: Comparative Forest Age Structure and Growth Response within the Buffalo Beats Research Natural Area' (McClenahen and Houston 1996). 1997 'Research Report: Comparative Forest Age Structure of Two Calcareous Clay Soil Sites within the Buffalo Beats Research Natural Area' (McClenahen and Houston 1997). 1998 (2 April) Controlled burn of Buffalo Beats (northern and southern sites). 1998 'Comparative age structure of a relict prairie transition forest and indigenous forest in Southeastern Ohio, USA' (McClenahen and Houston 1998).

Table 1 (continued)

1999 'Establishment record for Buffalo Beats Research Natural Area within Wayne National Forest, Athens County, Ohio' (Boyle and Ortt 1999). 2007 'Analysis of the historical floristic species diversity and abundance of Buffalo Beats prairie' (Larson 2007). 2009 (5 October) Four mature Quercus alba trees girdled in transition zone, six Q. alba girdled on southern lens. 2011 (6 April) Controlled burn of Buffalo Beats (northern and southern sites). 2014 'Assessment of Prairie Restoration and Community Change at the Buffalo Beats Research Natural Area, Athens County, OH' (Kapolka 2014).

Figure 1. Buffalo Beats prairie. Photograph taken by the author facing north on August 23, 2012.

publications between 1925 and 1975, and began to attract the attention of conservation groups in Ohio by the time of Wistendahl's publications in 1975 and 1981. Both the Ohio chapter of The Nature Conservancy and the Division of Natural Areas and Preserves of the Ohio Department of Natural Resources submitted recommendations for preservation and management of Buffalo Beats in the mid-1980's to the Wayne National Forest,

Athens Unit. Several reports of the natural history of the site and potential management plans were produced and commissioned by The Nature Conservancy, ODNR-Division of

Natural Areas, and the Wayne National Forest in order to establish the site as a Research

Natural Area with strict protections by the United States Forest Service.

At the time of Wistendahl’s sampling in 1962, the extent of the ‘true’ prairie at the site was estimated at 0.4 ha, amounting to little more than a gap in the canopy of dense mixed oak forest. The calcareous clay soils of Buffalo Beats lie atop a ridge, which extends beyond the area of the prairie studied by Wistendahl into a ‘transitional’ forest largely consisting of hardy Quercus alba trees and shrub species (Wistendahl 1975).

Thus, the prairie potentially occupied an area greater than initially quantified, perhaps extending to the edge of the clay soils prior to encroachment by woody species.

Wistendahl noted the abundance of many grass and forb species associated with prairie communities, such as Andropogon gerardii and Eryngium yuccifolium, and suggested the site could remain a quality relict over time due to the inhibition of rapid woody growth into the site by its clay soils. No active management was undertaken following this initial assessment.

In 1988, Hardin (1988) reported a study conducted in 1984 to follow-up on

Wistendahl’s report. He found that, in the 22 years following the initial collection of data at the site, shrubs and young trees had invaded into the central prairie along with many species of forest herbs. Though overall herbaceous species richness within the prairie increased, several species associated with prairies (so-called ‘prairie indicator’ species) were lost or decreased in frequency and vegetative cover in permanent plots. The increase in density of woody individuals along with the shift in composition of the herbaceous community suggested a rapid successional progression within the prairie not previously anticipated. This sudden shift was a distressing warning of the potential loss of a rare relict, and provoked the implementation of an active management plan by staff of the US

Forest Service, Wayne National Forest, Athens District. The primary goals of this management were to expand the extent of the prairie and promote the growth of prairie species populations, particularly rare species listed as threatened or endangered within the state of Ohio. In order to achieve these goals, the site was burned during the springs of

1987, 1996, 1998, and 2011, several mature trees were girdled in 2009 and allowed to die standing, and saplings were occasionally eliminated from the transition zone with hack- and-squirt treatments (Cheryl Coon, personal communication).

Following Hardin’s (1988) assessment of Buffalo Beats and the introduction of more active management by USFS, several additional studies provided valuable insight into the natural history of the site prior to its identification by modern ecologists. Kalisz and Boettcher (1990) used novel techniques of analyzing phytoliths (plant-derived silicon compounds) in soils to establish that the historical communities of the past several

19 hundred years occupying the clay lens at Buffalo Beats were most likely dominated by forbs and not grasses, and the surrounding shale soil has been dominated by trees. The natural history of Buffalo Beats was further expanded by McClenahen and Houston

(1998) who found that, while the clay soils did indeed effectively retard the growth of woody species, the oldest of the living trees growing upon the lens actually showed evidence of even further slowed growth during an extended period several centuries ago.

This period occurred prior to the beginnings of modern settlement in the area. This kind of growth pattern usually indicates photoinhibition by canopy closure or overtopping, and suggests that the prairie in the past was not entirely open and free from encroaching trees.

In the twenty-eight years between Hardin's 1984 sampling and 2012, a great deal of change in the structure and diversity of the plant communities at Buffalo Beats is anticipated to have occurred. Application of fire is generally expected to reduce the dominance of non-native and woody species in prairie communities, species that were becoming a concern prior to changes in management strategy of the Buffalo Beats site.

Preventing woody succession and improving the stability of the prairie is the goal of current management efforts, though no formal qualification of the status of the prairie community has been undertaken since Hardin. Have management actions by the Forest

Service been effective at preserving the prairie community at Buffalo Beats? Have rare prairie species populations expanded beyond the prairie described by Hardin in the

1980's? Through the quantification of changes in the aboveground plant communities at

Buffalo Beats since the 1980's, as well as comparisons of the plant communities and soil

20 conditions of the three vegetative zones, I assess whether management actions taken by the Forest Service have succeeded in preserving or expanding this rare community.

The prairie at Buffalo Beats has been of interest to botanical and ecological researchers for nearly seven decades (Jones 1944), though only recently has a nearby location of potentially similar soil conditions been documented (McClenahen and

Houston 1998). This location to the south of the known prairie has been deemed the

'southern lens' by local researchers, and was adopted into the management of Buffalo

Beats following its discovery. Once included in management of the Buffalo Beats site, prescribed fires and tree girdling were utilized to clear what was previously a closed canopy at the southern lens (Cheryl Coon, personal communication). The lens is included in this study as an initial description of the plant community present in permanent plots established by USFS.

When comparing the communities at Buffalo Beats across time periods, we may determine that they do indeed differ. But more importantly, how do they differ in key traits with which we are concerned? Is the prairie community more dominated by prairie grasses and forbs in 2012 than in previous decades? Through a variety of analyses of soil conditions and plant communities within the Buffalo Beats prairie, transition zone, forest, and southern lens, I aim to provide a useful description of the changing features of

Buffalo Beats over the past half-century. The prairie and forest communities are expected to have changed since Hardin's assessment, and the manner in which they are changing – be it a continuing trajectory towards succession, reversion towards a more prairie- or

21 savanna-like state, or a lack of significant shift whatsoever, will inform management of the site for years to come.

METHODS

Vegetative sampling of Buffalo Beats was conducted using both floristic inventory and quantitative quadrat methods. Floristic inventories of the prairie community were gathered every two weeks from mid-March until early October 2012 to ensure a robust collection of all species present. Voucher specimens of vascular plant species present at Buffalo Beats were collected and deposited in the Floyd Bartley

Herbarium (BHO) at Ohio University. I used the USDA PLANTS database (USDA

2012) for all nomenclature and plant authorities. The designation of plant species as

'prairie' species follows Cusick and Troutman (1978).

Quantitative measurements of prairie community composition were conducted in

September, and utilized permanent quadrats established at the site by previous researchers. One North-South transect was sampled on each prairie, each consisting of ten 0.5 × 2.0 m quadrats spaced 5 m between quadrats. Forest vegetation data was gathered using five sets of 10 × 10 m nested plots in both the transition and forest zones as previously sampled by Wistendahl (1975) and Hardin (1988). Each plot in the forest was paired with a counterpart in the transition along directional lines radiating from a central point in the prairie, for a total of 10 plots.

Nested plots were located along the same directional lines and in close approximation to the temporary plots sampled by previous researchers, but exact locations likely vary slightly from past publications. Within each 10 × 10 m plot, trees (≥

2.5 cm diameter at breast height, DBH) were tallied by species and individually measured for DBH. Within two 2 × 10 m quadrats per nested plot, saplings (< 2.5cm DBH and ≥

0.30 m in height) were counted by species and percent shrub cover by species was estimated. Finally, within four 0.5m × 2m quadrats per nested plot, seedlings (< 2.5cm

DBH and < 0.30 m in height) were counted by species and grass and forb species percent cover was estimated.

Soil samples for chemical and physical analyses were taken from six quadrats within each of the prairie, transition, and forest zones, as well as the ten permanent plots of the southern lens. Several 2.5 inch diameter soil cores were taken of the A horizon and composited for each quadrat. A horizon depth varied among the sample locations, from

3cm in some forest plots to over 10cm in the prairie, in which case samples did not exceed 10cm in depth. Composited soil samples were also taken at 20 points spaced 2 m apart along an East-West transect of the north prairie, which includes points in all three vegetative zones. Samples from the prairie, transition, forest, and southern lens zones were analyzed for total carbon and nitrogen content and pH. Samples from the East-West gradient of prairie to forest community were tested for pH. Total carbon and nitrogen content was analyzed using a Vario EL III CN elemental analyzer (DeForest 2011). pH was tested as a 1:2 soil:deoinized water solution with an accumet™ XL15 digital pH meter (McLean 1982). Texture samples of the southern lens were gathered as composites

25 of the soils of the ten individual permanent herbaceous plots, as well as eight temporary plots extending East-West along the elbow of the lens described by McClenahen and

Houston (1990). Texture for each sampled plot was tested using a modified hydrometer method (Bouyoucos 1962) described by Robertson (1999).

Seed banks were sampled from herbaceous plots in the northern lens and surrounding forest, as well as the herbaceous quadrats of the southern lens. Methods are modified from D’Souza and Barnes (2008) and Thompson and Grime (1979). In order to account for the shifting densities of species present in seed banks through seasons, soils were sampled in November 2012 and April 2013. In each of the prairie, transition, forest, and southern lens zones, ten plots used for herbaceous cover sampling were also sampled for soil seedbank analysis. Each quadrat soil sample was composited from several samples taken with a 5cm diameter soil core sampler to a depth of approximately 2.5 cm.

The seedbank samples were sieved to remove coarse rocks and biomass, and individually spread across ~2 cm beds of vermiculite in 10 × 10 cm aluminum pie pans to a depth of ~1 cm of soil. All flats were kept in the Ohio University greenhouse in a room designated for the study. Temperatures within the room tended to vary between 20-35 degrees Celsius through the year, and the peak room temperature during several summer days reached 47 degrees Celsius. Each individual sample was kept well-watered and observed for the emergence of individuals from seed for 6 months from the date of sampling. As individuals were distinguished by species (or genus, in several cases), they were recorded and removed from their flat.

Statistical Methods

Statistical tests were performed using the statistical software R (R Core

Development Team 2011) and the add-on package 'vegan' (Oksanen 2013). With data obtained for the northern prairie, total cover values of individual species of interest (e.g.,

Eryngium yuccifolium, Gentiana alba, Andropogon gerardii) were compared for significant differences among 2012, 1996, and 1986 prairie communities using analysis of variance (ANOVA). pH values and C:N ratios obtained for the four vegetative zones of Buffalo Beats were also tested by ANOVA for 2012 alone.

A permutational multivariate analysis of variance of the herbaceous communities of the prairie, transition, forest, and southern lens zones was completed using the adonis function of the vegan package in R. Adonis was also used to compare the prairie community of 2012 with those of 1996 and 1986. The prairie communities in 1986, 1996, and 2012, represented by vegetative data from permanent prairie plots, were compared using non-metric multidimensional scaling (NMDS). Likewise, the communities of the prairie, transition, and forest zones of the northern site of 2012 alone were compared by

NMDS using herbaceous plot data gathered in September 2012.

RESULTS

Prairie Community

58 herbaceous species, 11 graminoid species, and 10 woody (vine, shrub and tree) species were observed in the prairie of Buffalo Beats from March until October of 2012

(Table 2). Among these were several species not previously documented at Buffalo

Beats. Many were found during the spring and early summer, whereas previous samplings were restricted to the late summer and fall. Such species are thus not necessarily new members of the site since previous publications, but rather could have been previously unaccounted for residents. One such species, Sisyrinchium albidum, has not been previously documented by the USDA PLANTS Database (2013) for Athens

County.

Though many species recorded by Wistendahl (1975) and Hardin (1988) were not observed within the sampled plots in the prairie zone, many have been confirmed as present in 2012 through floristic survey (Table 2). These include Apocynum androsaemifolium, Asclepias tuberosa, Phlox subulata, Prunella vulgaris, and Frasera caroliniensis. Species observed in the prairie by Hardin in 1984 and not confirmed through quadrat sampling or floristic survey in 2012 include Houstonia longifolia,

Prenanthes serpentaria, Botrychium sp., Liatris cylindracea, and Smilacina racemosa.

Additionally, no observations of species of Liatris at Buffalo Beats have been documented since a sampling in 1996.

Overall vascular species diversity of the prairie within permanent plots during late summer sampling has increased, from 40 in 1984 to 47 in 2012 (Table 3). The increase is largely due to new 'non-prairie' species within the prairie, though previously undocumented prairie species have also been found in sampling. A similar trend of invasion of non-prairie species from samplings in 1962 to 1984, primarily from the surrounding forest communities, was noted by Hardin (1988). Several new species to the prairie were previously observed in the surrounding forest, and several more are common in the southern lens community, as well.

Species observed within permanent prairie plots in 2012 that were not previously documented within the prairie in 1984 or 1962 include Boehmeria cylindrica, Bromus purgans, Convolvulus arvensis, Danthonia spicata, Desmodium canadensis, Desmodium canescens, Phlox pilosa, Symphyotrichum lateriflorum, Elymus hystrix, Monarda fistulosa, Dichanthelium dichotomum, Dichanthelium latifolium, and Viola sororia.

Several species of Carex were collected from the prairie, including Carex cephalophora, Carex viriginiana, and Carex juniperorum. Carex species were not easily distinguishable during vegetative cover sampling, and are grouped to genus for the purposes of estimating frequency and cover in permanent plots.

From 1984 to 2012, herbaceous species diversity within the prairie increased slightly from 36 to 38 species. Herbaceous species diversity remained at 36 species within the transition zone, and decreased within the forest from 33 to 28 species (Table

4). Andropogon gerardii and Eryngium yuccifolium were found in several herbaceous quadrats within the transition zone in 2012, and were restricted to prairie quadrats in both

1962 and 1984. Nineteen plant species were observed in all three of the vegetative zones of the prairie and surrounding forest, an increase from twelve in 1984 and six in 1962.

Table 2. Plant species identified in Buffalo Beats prairie during biweekly floristic surveys from March through October 2012. Species marked with an asterisk (*) are considered 'prairie species' (Cusick and Troutman 1978).

Herbaceous and Vine Species Agrimonia rostellata Wallr. Ranunculus hispidus Michx. Amphicarpaea bracteata (L.) Fernald* Sabatia angularis (L.) Pursh* Antennaria plantaginifolia (L.) Richardson* Silphium trifoliatum L.* Apocynum androsaemifolium L. Sisyrinchium albidum Raf.* Asclepias tuberosa L.* Sisyrinchium angustifolium Mill. Boehmeria cylindrica (L.) Sw. Solidago juncea Aiton Cardamine flexuosa With. Symphyotrichum laeve (L.) Á. Löve & D. Löve* Claytonia virginica L. Symphyotrichum lateriflorum (L.) Á. Löve & D. Löve Convolvulus arvensis L. Taraxacum officinale F.H. Wigg. Coreopsis tripteris L.* Thalictrum thalictroides (L.) Eames & B. Bovin Daucus carota L. Trifolium pratense L. Desmodium canadense (L.) DC.* Vernonia gigantea (Walter) Trel. Desmodium canescens (L.) DC. Veronica officinalis L. Desmodium paniculatum (L.) DC. Vicia caroliniana Walter Erigeron annuus (L.) Pers. Viola sororia Willd. Eryngium yuccifolium Michx.* Viola triloba Schwein. Euphorbia corollata L.* Zizia aptera (A. Gray) Fernald* Frasera caroliniensis Walter Galium concinnum Torr. & A. Gray Graminoids Gentiana alba Muhl. ex Nutt.* Andropogon gerardii Vitman* Geranium maculatum L. Bromus purgans L. Gillenia stipulata (Muhl. ex Willd.) Baill. Carex cephalophora Muhl. ex Willd. Helianthus divaricatus L. Carex juniperorum Catling, Reznicek & Crins Helianthus hirsutus Raf.* Danthonia spicata (L.) P. Beauv. ex Roem. & Schult. Helianthus strumosus L.* Dichanthelium dichotomum (L.) Gould Hypericum perforatum L. Dichanthelium latifolium (L.) Gould & C.A. Clark Hypoxis hirsuta (L.) Coville* Elymus hystrix L. Ipomoea pandurata (L.) G. Mey.* Sorghastrum nutans (L.) Nash* Krigia biflora (Walter) S.F. Blake* Lespedeza hirta (L.) Hornem. Vine, Shrub and Tree Species Lespedeza virginica (L.) Britton Carpinus caroliniana Walter Liparis liliifolia (L.) Rich. ex Ker Gawl. Ceanothus americanus L.* Lobelia spicata Lam.* Parthenocissus quinquefolia (L.) Planch. Medicago lupulina L. Prunus serotina Ehrh. Melilotus officinalis (L.) Lam. Quercus alba L. Monarda fistulosa L.* Rosa carolina L.* Oligoneuron rigidum (L.) Small* Rubus flagellaris Willd. Packera aurea (L.) Á. Löve & D. Löve* Smilax rotundifolia L. Phlox pilosa L.* Toxicodendron radicans (L.) Kuntze Phlox subulata L. Vitis aestivalis Michx. Potentilla simplex Michx. Prunella vulgaris L.

Table 3. Herbaceous and graminoid species mean vegetative cover and plot frequency within prairie, transition, and forest zones at Buffalo Beats Research Natural Area in September 2012. Species are arranged in order of cover and frequency as per Wistendahl (1975) and Hardin (1988).

Prairie Transition Forest Species Cover a Frequency a Cover b Frequency b Cover b Frequency b Andropogon gerardii 25 70 2 20 Eryngium yuccifolium 6 90 1 15 Carex spp. 5 50 2 35 1 40 Helianthus hirsutus 3 30 2 55 +c 25 Sorghastrum nutans 5 30 Potentilla simplex 2 90 2 100 1 60 Coreposis tripteris 2 80 1 40 Silphium trifoliatum 2 70 1 45 + 20 Solidago juncea 2 60 2 55 + 40 Symphyotrichum lateriflorum 2 60 1 60 + 25 Symphyotrichum laeve 1 70 + 60 + 30 Euphorbia corollata 1 60 + 10 Phlox pilosa 1 60 + 15 Oligoneuron rigidum 1 50 Gentiana alba 1 40 Zizia aptera 1 40 1 40 + 10 Helianthus strumosus 1 30 2 45 1 45 Amphicarpaea bracteata + 70 Vicia caroliniana + 40 + 40 + 5 Desmodium spp. + 30 Galium concinnum + 30 + 50 1 65 Elymus hystrix + 30 + 15 + 30 Ipomoea pandurata + 30 + 40 + 20 Convolvulus arvensis + 20 Desmodium canescens + 20 Helianthus divaricatus + 20 + 20 + 5 Lespedeza virginica + 20 Dichanthelium latifolium + 20 + 30 + 65 Boehmeria cylindrica + 10 Bromus purgans + 10 + 30 + 40 Danthonia spicata + 10 1 20 + 15 Desmodium canadense + 10 Desmodium paniculatum + 10 + 5 Monarda fistulosa + 10 Dichanthelium dichotomum + 10 + 30 + 30 Panicum sp. + 10 Poa sp. + 10 Viola sororia + 10 + 20 + 40 Gillenia stipulata 1 35 + 5 Krigia biflora 1 10 Lespedeza repens + 35 + 5

Table 3(continued)

Eupatorium rugosum + 25 + 35 Desmodium nudiflorum + 20 + 55 Galium circacaezans + 10 + 35 Calystegia sepium + 5 Cardamine flexuosa + 5 + 5 Geranium maculatum + 5 + 15 Lespedeza hirta + 5 Ranunculus hispidus + 5 + 5 Symphyotrichum lowrieanum + 5 Solidago caesia + 25 Eurybia divaricata + 20 Antennaria plantaginifolia + 10 Plantago sp. + 5 Symphyotrichum patens + 5 a Based on ten 0.5 × 2m quadrats b Based on twenty 0.5 × 2m quadrats c + = less than 1%

Species importance values (determined by the sum of relative frequency and relative cover) for all species observed in permanent plots in the northern prairie in 1962,

1984, and 2012 are presented in Table 4. The most important two plant species observed during all three samplings were Andropogon gerardii and Eryngium yuccifolium, and species importance below these two shifted widely during the five decades of study at the site. Sorghastrum nutans was also recorded in relative abundance for the first time, and though it was not recorded in the prairie, it may have been confused with A. gerardii in the past (Hardin 1988). Overall prairie species importance dropped from

1962 to 1984 despite the presence of several additional prairie species observed within the plots, and prairie species importance rebounded slightly by 2012 (Table 4).

A graphical representation by non-metric multidimensional scaling (NMDS) of herbaceous plot vegetative data from the prairie, transition, and forest communities in

2012 shows a clear gradient of difference between the three communities that

33 corresponds with the physical gradient of prairie to forest (Figure 8). A large number of species were found in common among the three zones, but several species play an important role in defining each community. A visualization by NMDS of the differences in community structure of the Buffalo Beats prairie among the years 1986, 1996, and

2012 shows little community change as time has passed (Figure 9). Positions of the years do not show a directional shift, and show a great deal of overlap. Community analysis by the Adonis function in R also showed no significant change in the prairie community between 1986 and 2012 (P > 0.05).

The prairie species Andropogon gerardii and Eryngium yuccifolium were the two most important species within the prairie in 2012 (Table 4), and were also found in relative abundance in the transition. Likewise, the prairie species Helianthus hirsutus,

Coreopsis tripteris, Silphium trifoliatum, Symphyotrichum laeve, Euphorbia corollata,

Zizia aptera, and Phlox pilosa were among the twenty most important species in the prairie, and their populations also extended into the transition and forest.

Species that distinguish the prairie community include Sorghastrum nutans,

Gentiana alba, Amphicarpaea bracteata, Convolvulus arvensis,Oligoneuron rigidum, and several species of Desmodium. Species distinctive of the forest include

Symphyotrichum patens, Eurybia divaricata, Eupatorium rugosum, Galium concinnum,

Galium circaezans, Antennaria plantaginifolia, Solidago caesia, and Bromus purgans.

The transition zone, as the name suggests, shares most species with neighboring communities, though Krigia biflora, Danthonia spicata, Gillenia stipulata, and

Helianthus strumosus are important species within the transition relative to other zones.

Table 4. Importance values (IV) for plant species present within permanent plots of the Buffalo Beats prairie during sampling in the late summers of 1986, 1996, and 2012. Species marked with an asterisk (*) are considered ‘prairie species’ (Cusick and Troutman 1978).

1962 1984 2012 Species IV Species IV Species IV Andropogon gerardii* 77.1 Andropogon gerardii* 35.5 Andropogon gerardii* 41.6 Eryngium yuccifolium* 19.2 Eryngium yuccifolium* 16.9 Eryngium yuccifolium* 14.6 Oligoneuron rigidum* 16.5 Toxicodendron radicans 16.4 Carex spp. 10.3 Helianthus hirsutus* 12.2 Silphium trifoliatum* 12.4 Sorghastrum nutans* 8.5 Vicia caroliniana 9.2 Euphorbia corollata* 10.6 Potentilla simplex 8 Amphicarpaea bracteata* 7.2 Helianthus hirsutus* 10 Silphium trifoliatum* 7.5 Euphorbia corollata* 7.2 Vicia caroliniana 8 Coreposis tripteris* 7.4 Liatris cylindracea* 7.2 Helianthus divaricatus 6.7 Solidago juncea 7.2 Coreopsis tripteris* 5.2 Galium concinnum 6.5 Toxicodendron radicans 6.7 Symphyotrichum Silphium trifoliatum* 5.2 Houstonia longifolia* 6.5 lateriflorum 6.3 Phlox subulata 4.7 Potentilla simplex 6.5 Helianthus hirsutus* 6.1 Desmodium paniculatum 4.3 Solidago juncea 5.7 Symphyotrichum laeve* 5.9 Helianthus strumosus* 4.3 Oligoneuron rigidum* 5.7 Oligoneuron rigidum* 5.2 Symphyotrichum laeve* 3.3 Coreopsis tripteris* 4.9 Amphicarpaea bracteata* 4.9 Gentiana alba* 3.3 Phlox subulata 4.1 Euphorbia corollata* 4.5 Lespedeza hirta 3.3 Lespedeza hirta 3.6 Phlox pilosa* 4.5 Liatris scariosa* 3.3 Symphyotrichum laeve* 3.3 Gentiana alba* 4 Melilotus alba 3.3 Carex cephalophora 3.3 Zizia aptera* 3.8 Lespedeza repens 1.3 Ipomoea pandurata* 3.3 Rosa carolina* 3.5 Potentilla simplex 1.3 Amphicarpaea bracteata* 2.6 Helianthus strumosus* 3.5 Apocynum Zizia aptera* 1.3 androsaemifolium 2 Vicia caroliniana 3.2 Melilotus alba 2 Desmodium paniculatum 3.1 Prenanthes serpentaria 2 Hystrix patula 2.5 Zizia aptera* 2 Ipomea pandurata* 2.2 Agrimonia rostellata 1.2 Galium concinnum 2 Asclepias sp. 1.2 Lespedeza virginica 2 Asclepias tuberosa* 1.2 Dichanthelium latifolium 1.7 Botrychium sp. 1.2 Helianthus divaricatus 1.6 Galium circaezans 1.2 Convolvulus arvensis 1.4 Gentiana alba* 1.2 Desmodium canescens 1.4 Geranium maculatum 1.2 Poa sp. 1.4 Gillenia stipulata 1.2 Prunus serotina 1.1 Helianthus strumosus* 1.2 Desmodium canadense* 0.9 Parthenocissus Lespedeza virginica 1.2 quinquefolia 0.9 Liatris cylindracea* 1.2 Quercus velutina 0.9 Prunella vulgaris 1.2 Rubus allegheniensis 0.9

Smilacina racemosa 1.2 Smilax rotundifolia 0.9 Table 4 (continued)

Swertia caroliniensis 1.2 Vitis aestivalis 0.9 Rosa carolina* 1.2 Carpinus caroliniana 0.8 Ceanothus americanus* 1.2 Ceanonthus americanus* 0.8 Danthonia spicata 0.8 Monarda fistulosa* 0.8 Dichanthelium dichotomum 0.8 Panicum sp. 0.8 Boehmeria cylindrica 0.7 Bromus purgans 0.7 Viola sororia 0.7 Total Species 21 40 47 Total Prairie Species 13 18 19 Total IV 199.9 199.7 199.9 Prairie Species IV 172.5 120.9 130.2

Southern Lens

The herbaceous community of the southern lens shared thirteen species with the community of the northern prairie, and contained sixteen species not shared between them (Table 5). Notable prairie species found in the southern lens include Ipomoea pandurata, Silphium trifoliatum, Helianthus hirsutus, Amphicarpaea bracteata, Rosa carolina, and Ceanothus americanus. Eryngium yuccifolium and Gentiana alba have also been observed growing on the southern lens, though were not documented within sampled plots in 2012.

The dominant herbaceous species was Symphyotrichum pilosum, and no species was estimated to have greater than 5 percent vegetative cover across the sampled plots.

Only three species – Panicum sp., Potentilla simplex, and Ipomoea pandurata – were observed in at least half of the plots, the rest occurring in 40 percent of plots or fewer.

Table 5. Herbaceous and graminoid species mean vegetative cover and plot frequency in permanent plots in the 'southern lens' habitat at Buffalo Beats Research Natural Area in September 2012.

Species Name Cover Frequency Symphyotrichum pilosum 5 40 Potentilla simplex 2 80 Ipomoea pandurata 2 80 Solidago juncea 1 40 Polygonum hydropiperoides 1 10 Panicum spp. 1 60 Eupatorium rugosum 1 30 Silphium trifoliatum 1 30 Helianthus hirsutus 1 40 Carex spp. 1 30 Elymus hystrix 1 20 Symphyotrichum lateriflorum +a 30 Symphyotrichum cordifolium + 40 Helianthus divaricatus + 30 Phytolacca americana + 10 Geranium maculatum + 30 Desmodium spp. + 30 Galium concinnum + 30 Eurybia divaricata + 10 Pilea pumila + 10 Agrimonia pubescens + 20 Amphicarpaea bracteata + 10 Cirsium altissimum + 10 Elaeagnus umbellata + 10 Smilacina racemosa + 10 Tridens flavus + 10 Vitis riparia + 10 Vicia caroliniana + 20 Galium circaezans + 10 Leersia virginica + 10 Viola spp. + 10 a + = less than 1%

Table 6. Shrub and vine species mean vegetative cover and plot frequency within the southern lens community at Buffalo Beats Research Natural Area in September 2012.

Species Cover Frequency Rubus allegheniensis 12 60 Rubus sp. 7 20 Rubus flagellaris 6 20 Rhus glabra 3 10 Rosa carolina 2 50 Parthenocissus quinquefolia 1 60 Crataegus sp. 1 40 Smilax rotundifolia 1 40 Smilax glauca +a 20 Vitis vulpina + 10 Vitis spp. + 10 Toxicodendron radicans + 10 Ceanonthus americana + 10 a + = less than 1%

Table 7. Shrub and vine species mean vegetative cover and plot frequency within prairie, transition, and forest zones at Buffalo Beats Research Natural Area in September 2012.

Prairie Transition Forest Species Cover Frequency Cover Frequency Cover Frequency Toxicodendron radicans 2 60 1 80 +a 50 Rosa carolina 1 40 1 90 1 90 Smilax rotundifolia + 10 3 70 2 100 Rubus flagellaris + 10 3 70 1 80 Parthenocissus quinqefolia + 10 + 80 + 60 Vitis aestivalis + 10 + 50 + 30 Ceanothus americanus + 10 + 30 + 10 Viburnum acerifolium + 10 1 40 Vaccinium vacillans + 30 a + = less than 1%

Shrubs and Vines

Hamamelis virginiana and Lindera benzoin were not observed in any quadrats during 2012 sampling. Average cover of Toxicodendron radicans decreased in all three zones since 1984, and Rubus flagellaris expanded from the forest into the transition zone and prairie. As of 2013, a large swath of R. flagellaris occupies an area in the transition zone previously shaded by now-dead Quercus alba trees. Smilax rotundifolia was also observed more frequently and in a greater extent of vegetative cover in all three zones, and was observed in all sampled quadrats of the forest.

The shrub and vine community of the southern lens was much more diverse than in the northern prairie and forest, with thirteen species counted (Table 6). The understory was dominated by species of Rubus, which formed a thick mat of vegetation over several of the plots. The dominance of shrub species was greatest in areas formerly shaded by large Quercus alba trees, which were girdled in 2003. Fifteen tree species were also observed within permanent plots of the southern lens, compared to only three in the northern prairie (Table 7). Cover and frequency of Quercus and Carya species were particularly large relative to other members of the seedling cohort.

Table 8. Seedling cover and frequency of tree species observed in permanent plots of the northern prairie and southern lens of Buffalo Beats RNA in September 2012.

Northern Prairie Southern Lens Species Cover Frequency Cover Frequency Ostrya virginiana +a 10 Prunus serotina + 10 + 10 Quercus alba + 10 5 50 Quercus rubra 2 30 Carya ovata 1 30 Quercus velutina 1 30 Fraxinus pennsylvanica 1 20 Ulmus rubra + 30 Cercis canadensis + 30 Acer rubrum + 10 Carya glabra + 10 Carya sp. + 10 Lindera benzoin + 10 Cornus florida + 10 a + = less than 1%

Seedlings, Saplings, and Trees

Seedlings within the transition zone were less dense in 2012 than in 1984 (Table

8). Seedlings of Quercus alba were the most dense and frequent observed in 2012, followed by Prunus serotina and Crataegus sp. The seedling community in 1984 was dominated by Crataegus sp., Cornus florida, and Quercus velutina, but neither Cornus florida nor Q. velutina seedlings were observed in plots in 2012. The total species diversity among seedlings decreased from fifteen in 1984 to eight in 2012.

Within the forest in 2012, the woody seedling community was dominated by

Crataegus sp., Quercus alba, Ulmus rubra, and Prunus serotina. and twelve tree species were observed as seedlings. Of the fourteen species observed as seedlings within the forest in 1984, Sassafras albidum, Cornus florida, and Querus prinus were most dense

40 and frequent. Sassafras albidum seedlings were not observed in the 2012 forest, and

Cornus florida and Quercus prinus seedlings were infrequent.

Single seedlings of three tree species; Ostrya virginiana, Quercus velutina and

Prunus serotina, were found within permanent prairie plots (Table 8). Within twelve meters of a permanent reference pipe located near the center of the prairie, twenty-three

Quercus alba seedlings, two Ostrya virginiana seedlings, two Quercus rubra seedlings, and one Carya ovata seedling were located. This is a decrease from seedling densities observed in 1984, when eleven seedlings of four species were found in the same plots and forty-two seedlings were found within twelve meters of the same reference pipe.

However, seedling densities are still much greater than those observed in 1962, when no seedlings were found in prairie plots and only six seedlings and saplings were located within twelve meters of the central reference point.

Sapling populations within the transition zone in both 1984 and 2012 were dominated by Ostrya virginiana and Crataegus sp., though by 2012 Quercus alba saplings were much more frequent and dense than in previous samplings (Table 9).

During 1984, several species co-dominated the forest sapling community of Buffalo

Beats, including Sassafras albidum, Ostrya virginiana, Cornus florida, Quercus prinus, and Crataegus sp. This condition changed little by 2012, though O. virginiana became much more dense and appeared in every plot during the latter sampling. Quercus alba also emerged into the forest sapling community.

The 2.5-9.9 cm DBH class of the transition zone shifting dramatically from 1984 to 2012, with a decrease in species diversity from ten species in 1984 to only one of

41 sparse individuals, Quercus alba, in 2012. Both Q. alba and Q. rubra were observed in the 10-25.3 cm DBH class in the transition zone in both 1984 and 2012, and Q. velutina was lost and succeeded by Acer saccharum. Overall density and basal area plummeted within the class by 2012, and was only a third of the observed 1984 values in both categories.

Transition Seedlings Saplings 2.5-9.9 10-25.3 25.4 All Trees Species Da Fa Db Fb Dc BAc,e Fc IVd D BA F IV D BA F IV D BA F IV Quercus alba 8500 60 2650 80 20 0.09 20 300 60 2.14 60 166 100 14.48 60 229 180 16.71 60 190 Ostrya virginiana 500 5 1500 100 Quercus rubra 1000 5 400 30 40 0.72 40 89 20 6.02 20 71 60 6.74 40 85 Quercus velutina 350 30 Crataegus sp. 2500 15 2600 100 Cornus florida 250 40 Carya ovata 600 70 Acer saccharum 500 5 20 0.37 20 45 20 0.37 20 26 Tilia sp. Prunus serotina 3500 25 450 70 Acer rubrum 200 30 Sassafras albidum 2000 15 350 50 Ulmus rubra 1000 10 400 70 Nyssa sylvatica 200 30 Quercus prinus 50 10 Quercus coccinea 50 10 Carya sp. 100 10 Totals 19500 10150 20 0.09 300 120 3.23 300 120 20.5 300 260 23.82 301 a Based on twenty 0.5 × 2m quadrats b Based on ten 2 × 10m quadrats c Based on five 10 × 10m quadrats d Relative density + relative basal area + relative frequency, maximum value of 300 e Basal area reported in m2

Forest Seedlings Saplings 2.5-9.9 10-25.3 25.4 All Trees Species Da Fa Db Fb Dc BAc,e Fc IVd D BA F IV D BA F IV D BA F IV Quercus alba 9000 30 450 40 80 1.7 40 107 200 19.85 80 247 280 21.55 80 155 Ostrya virginiana 1000 5 4050 100 100 0.32 20 164 100 0.32 20 27 Quercus rubra 1000 10 850 70 40 1.42 40 79 40 3.89 20 53 80 5.31 60 57 Quercus velutina 1000 10 1000 50 Crataegus sp. 13000 40 1750 80 Cornus florida 1000 5 750 60 20 0.02 20 42 20 0.02 20 12 Carya ovata 500 5 600 70 Acer saccharum 100 10 20 0.03 20 45 20 0.23 20 30 40 0.26 20 16 Prunus serotina 3500 35 400 60 Acer rubrum 50 10 Sassafras albidum 1200 70 Ulmus rubra 4500 15 300 50 Nyssa sylvatica 100 20 Quercus prinus 500 5 200 20 20 0.05 20 49 40 1.65 40 84 60 1.7 40 33 Quercus stellata 50 10 Cercis canadensis 400 30 Hamamelis virginiana 500 5 Acer saccharum 500 5 Totals 36000 12250 160 0.42 300 180 5 300 240 23.74 300 580 29.16 300 a Based on twenty 0.5 × 2m quadrats b Based on ten 2 × 10m quadrats c Based on five 10 × 10m quadrats d Relative density + relative basal area + relative frequency, maximum value of 300 e Basal area reported in m2

The large trees of the transition (> 25.3 cm DBH) likewise decreased in numbers, though Quercus rubra joined the class by 2012 and total basal area of the larger tree class increased from 12.02 m2 ha-1 to 20.5 m2 ha-1 despite the lower density of individuals.

Overall density of individual trees within transition zone plots decreased from 1580 per ha in 1984 to 260 per ha in 2012, and total basal area of trees sampled decreased from

25.58 m2 ha-1 to 23.82 m2 ha-1.

The 2.5-9.9 cm DBH class of trees within the forest immediately surrounding

Buffalo Beats underwent a similar drop in species diversity to the transition zone between

1984 and 2012, decreasing from twelve species in 1984 to only four in 2012 (Table 10).

No new species entered the size class in that time, and those remaining boasted very infrequent individuals within sample plots. The 10-25.3 cm DBH class of trees in the forest remained comparatively stable, retaining most species from 1984 though halving the observed density of individuals.

The largest DBH class boasted four Quercus species and Sassafras albidum in

1984, and only Quercus alba and Quercus rubra remained in the 2012 sampling. The density of large individuals increased from 200 to 240 per ha, and basal area also increased from 22.77 to 23.74 m2 ha-1. The importance and corresponding contributing values of Quercus alba also all increased dramatically. Overall species diversity of trees within the forest zone decreased from fifteen to six by 2012, with density of individual trees likewise dropping from 1000 per ha to 580 per ha. Basal area dropped from 30.79 to

29.16 m2 ha-1, and overall importance of species shifted from a relatively even spread among many species to a dominance of Quercus alba.

Figure 5. Box plot of pH values of soils sampled from the prairie, transition, forest, and southern lens zones of the Buffalo Beats Research Natural Area in 2013. Boxes represent the interquartile range of values between the first and third quartiles of pH values, lines representing median values contained within them. Whiskers extend to maximum and minimum values. No significant differences were observed among the pH values or H+ ion concentrations of soils from the sampled locations (P > 0.05).

Soil Conditions

Mean pH of soils in the northern prairie, transition, and forest were not significantly different from each other, or from the soils of the southern lens (Figure 5, P

> 0.05). However, the mean pH of the four centermost prairie plots was significantly greater than that of all other locations (P < 0.05).

Mean soil carbon to nitrogen ratios varied for the prairie, transition, forest, and southern lens zones. Significant differences were observed between the prairie and southern lens and forest zones (P < 0.05), but not between the prairie and transition

(Figure 6, P = 0.78) Significant differences were also observed between C:N ratios of

Figure 7. Mean percentage of sand, silt, and clay of A horizon soils of the southern lens habitat of Buffalo Beats RNA. Error bars indicate 95% confidence intervals of the mean of each particle type.

soils from the forest and the transition and southern lens (P < 0.05). Soils from the transition and southern lens did not have significantly different C:N ratios (P = 0.29).

The forest soils had an average C:N ratio of 14.2, which was the highest observed among the locations tested. The prairie soils, by contrast, contain a much lower ratio of

10.6, and the transition and southern lens soils fall between the two extremes, at 11.3 and

12.4, respectively.

The texture analysis of soils of the southern lens at Buffalo Beats revealed that the lens is predominantly clay. The mean percentages of sand, silt, and clay on permanent plots were 31, 17.5, and 51.5, respectively (Figure 7). Percentage of clay was greater in one half of the plots than the other, where percent clay approached that reported by

Wistendahl (1975). Overall, the soils of the southern lens contain less clay and more silt and sand than the northern prairie, but are still well within the clay soil category according to the national soil survey handbook of the USDA-NRCS (2013).

Texture analysis of temporary plots extending across the East-West elbow of the southern lens (as delineated by McClenahen and Houston 1990) revealed a similar clay soil texture profile to that of the permanent plots, though with slightly less clay and greater percentages of sand and silt.

A B

C D

Figure 8. Three-dimensional NMDS of plant community composition of the prairie, transition, and forest zones of Buffalo Beats RNA in September 2012. Plot grouping is shown in A and C, with labeled ellipses indicating 95% CI of each group. Green, blue, and red diamonds indicate prairie, transition, and forest plots, respectively. Associated species data are shown in B and D. Acronyms represent the first two letters of the genus and specific epithet, respectively. Full species names provided in Table 13.

A B

C D

Prairie Transition Forest Southern Lens Species Count Frequency Count Frequency Count Frequency Count Frequency Acalypha virginica 0 0 0 0 0 0 10 10 Amphicarpaea bracteata 1 10 0 0 0 0 0 0 Andropogon gerardii 1 10 0 0 0 0 0 0 Agrimonia pubescens 0 0 0 0 0 0 1 10 Bromus purgans 1 10 1 10 1 10 0 0 Cardamine hirsuta 1 10 14 20 0 0 0 0 Carex spp. 3 20 0 0 2 20 6 30 Cirsium altissimum 0 0 1 10 0 0 0 0 Claytonia virginica 1 10 4 30 12 50 2 20 Conyza sp. 1 10 1 10 0 0 0 0 Coreopsis tripteris 1 10 2 10 0 0 0 0 Danthonia spicata 3 20 1 10 7 10 4 40 Dichanthelium dichotomum 1 10 0 0 0 0 0 0 Dichanthelium latifolium 1 10 2 20 0 0 1 10 Elymus hystrix 5 30 6 30 0 0 1 10 Epilobium sp. 0 0 4 10 0 0 4 20 Erechtites hieraciifolia 2 20 5 30 2 20 17 70 Erigeron sp. 1 10 0 0 0 0 0 0 Eupatorium rugosum 0 0 1 10 4 10 5 40 Eupatorium sessilifolium 0 0 0 0 1 10 0 0 Eurybia divaricata 0 0 0 0 4 30 2 20 Galium concinnum 0 0 0 0 2 20 0 0 Gillenia stipulata 0 0 4 30 1 10 0 0 Helianthus hirsutus 2 10 0 0 1 10 0 0 Hypericum sp. 0 0 3 10 0 0 0 0 Lactuca sp. 0 0 0 0 0 0 1 10 Lobelia spicata 0 0 2 20 1 10 0 0 Physalis sp. 0 0 1 10 0 0 0 0 Pilea pumila 0 0 14 20 0 0 21 40

Table 11 (continued)

Polygonum hydropiperoides 0 0 1 10 0 0 31 30 Potentilla simplex 0 0 1 10 0 0 1 10 Prunella vulgaris 0 0 0 0 2 10 0 0 Ranunculus hispidus 0 0 0 0 1 10 0 0 Solidago juncea 1 10 9 60 3 30 6 30 Symphyotrichum laeve 1 10 0 0 1 10 0 0 Symphyotrichum lateriflorum 9 60 20 70 12 40 49 80 Trifolium pratense 1 10 0 0 0 0 0 0 Vicia caroliniana 1 10 1 10 0 0 0 0 Viola sororia 0 0 1 10 2 20 1 10 Viola triloba 0 0 0 0 1 10 0 0 Total 38 20 99 23 60 19 163 18

Prairie Transition Forest Southern Lens Species Count Frequency Count Frequency Count Frequency Count Frequency Acalypha virginica 0 0 1 10 0 0 1 10 Andropogon gerardii 1 10 0 0 0 0 0 0 Antennaria plantaginifolia 0 0 0 0 2 20 0 0 Cardamine hirsuta 0 0 132 30 1 10 0 0 Carex sp. 0 0 1 10 0 0 1 10 Claytonia virginica 1 10 0 0 0 0 0 0 Danthonia spicata 2 20 1 10 4 10 0 0 Dichanthelium dichotomum 0 0 1 10 0 0 0 0 Dichanthelium latifolium 3 20 0 0 0 0 0 0 Erechtites hieraciifolia 0 0 8 5 6 50 12 60

Table 12 (continued)

Eupatorium rugosum 0 0 2 20 0 0 0 0 Eurybia divaricata 0 0 1 10 2 20 2 10 Galium concinnum 0 0 0 0 1 10 0 0 Helianthus hirsutus 1 10 0 0 0 0 0 0 Hypericum sp. 0 0 0 0 5 10 0 0 Lactuca sp. 0 0 0 0 0 0 0 0 Lobelia infalata 0 0 0 0 0 0 0 0 Oxalis sp. 0 0 0 0 0 0 1 10 Physalis sp. 1 10 0 0 0 0 0 0 Phytolacca americana 1 10 1 10 2 10 0 0 Pilea pumila 0 0 0 0 0 0 4 30 Polygonum hydropiperoides 0 0 12 20 0 0 16 20 Solidago juncea 5 40 2 20 2 20 3 30 Symphyotrichum lateriflorum 1 10 4 20 4 30 0 0 Trifolium pratense 0 0 0 0 0 0 0 0 Vicia caroliniana 0 0 0 0 0 0 1 10 Viola sororia 2 10 0 0 2 20 0 0 Total 18 10 166 12 31 11 41 9

Soil Seedbank

The seedbank of the northern prairie of Buffalo Beats bore several species not observed growing in the prairie during 2012. These include Erechtites hieraciifolia,

Erigeron sp., Physalis sp., and Phytolacca americana. Within the March sampling period

(Table 11), the species which emerged with the greatest numbers and frequencies from the prairie samples were Symphyotrichum lateriflorum and Elymus hystrix, and several species were found with only one individual from a single plot. The transition samples bore a great number of Cardamine hirsuta and Pilea pumila seedlings, but only from

20% of samples. Relatively more frequent species include Claytonia virginica, Elymus

53 hystrix, Erechtites hieraciifolia, and Gillenia stipulata, and Solidago juncea and

Symphyotrichum lateriflorum were by far the most abundant and frequent species in the transition.

Among the March forest samples, Claytonia virginica and Symphyotrichum lateriflorum were the most abundant and frequent species to germinate, followed by

Eurybia divaricata and Solidago juncea. The spring seedbank samples of the southern lens produced a large number of Symphyotrichum lateriflorum, Polygonum hydropiperoides, Pilea pumila, and Erechtites hieraciifolia, followed by Carex spp.,

Solidago juncea, Eupatorium rugosum, and Danthonia spicata. The species abundances of the germinated species in the March seedbank samples of the four locations varied from 18 to 23 species.

Among the May seedbank samples from the prairie community (Table 12),

Solidago juncea was the most frequent and abundant species, followed by Dichanthelium latifolium and Danthonia spicata. Among the transition samples, a relatively tremendous number of Cardamine hirsuta seedlings germinated, though Erechtites hieraciifolia was more frequent. Polygonum hydropiperoides, Symphyotrichum lateriflorum, Solidago juncea, and Eupatorium rugosum were the remaining species with multiple seedlings in multiple plots in the transition. Among the forest samples, Erechtites hieraciifolia and

Symphyotrichum lateriflorum were relatively frequent and abundant, followed by

Antennaria plantaginifolia, Eurybia divaricata, Solidago juncea, and Viola sororia.

Among the southern lens samples, Erechtites hieraciifolia was the most well-represented species, followed by Pilea pumila, Solidago juncea, and a large number of Polygonum

54 hydropiperoides from only 20% of the plots. The species abundances of germinated species from the four communities varied from 9 to 12 species.

DISCUSSION

Prairie Community

The increase in importance of prairie species of the northern prairie, as well as the increase and stability of important prairie species of conservation interest is a good indication of restoration of the prairie community relative to the conditions observed by

Hardin in 1984. Though numerous non-prairie species have invaded from the surrounding forest, their populations remain infrequent and small, and are thus relatively unimportant in the greater community. The application of fire would be expected to promote fire- adapted prairie species, so the increase in prairie species importance following several prescribed burns confirms our expectations.

The ratio of prairie species at Buffalo Beats compares well to other remnant prairies in Ohio, such as the Daughmer savanna. Mack and Boerner (2004) reported that one-fifth of forb species and one-third of graminoid species at Daughmer were listed as prairie species by Cusick and Troutman (1978). In 2012, over one-third of forb species at

Buffalo Beats were prairie species, and one-fifth of graminoids were prairie species. In addition, though invasive species such as Microstegium vimineum have been problematic at some remnant prairies in the Midwest (Anderson et al. 2000, Klips 2003), exotic species are not currently in abundance at Buffalo Beats. Furthermore, no aggressive invasive species have been confirmed as being present in the northern site. Eleagnus umbellata is represented by a small population in the southern lens.

The NMDS ordinations of the prairie, transition, and forest communities in 2012 shows a clear gradient of differing community structure that is in line with the goals of the management plan envisioned by conservation agencies cooperating on management

56 of Buffalo Beats in the 1980's (The Nature Conservancy, 1984). Species that occurred across the communities and contributed to greater similarity included several prairie species that Hardin (1988) did not observe beyond the prairie. Hardin worried that the three zones were becoming more similar because of woody encroachment, but current similarity among the herbaceous communities is at least partly due to prairie species establishing beyond the prairie into the transition and forest.

There are some indications that the process of succession is continuing within the northern prairie. Several new vine species have invaded the prairie, and more species are found growing in all three vegetative zones than ever before. The population growth of

Rubus species in particular is troubling, and likely due to increased light exposure in areas formerly shaded along the edge of the prairie.

Fewer tree species were noted within permanent plots and within the center of the prairie than in 1984, as well as fewer individual seedlings and saplings. Saplings within the prairie have been targeted in recent years by USFS crews for removal by hack-and- squirt herbicide treatments, and the effect is noticeable. No living saplings were observed within ten meters of the center of the prairie, though numerous dead standing stems showed evidence of herbicide treatment. The lower density of seedlings, and dominance of Quercus alba within the seedling cohort, is evidence of the effect of fire treatment on the woody community within the prairie.

The burning regime at Buffalo Beats has included solely dormant season burns, which can be effective at reducing woody species density in tallgrass prairie (Adams

1982). Indeed, fire has been effective at stemming woody encroachment into the Buffalo

Beats prairie but may not be an optimal strategy for restoring the prairie community.

Hutchinson and colleagues (2005) found that at another site in southern Ohio, dormant- season burns had little effect on herbaceous layer vegetation due to low emergence of perennial herbs at the time of burning and low fire intensities. Fire intensities at Buffalo

Beats have reportedly been spotty, the fire in 2011 being of a particularly low intensity.

Burning while vegetation has developed would provide additional fuel for fires, and could provide more effect on non-prairie species than if growth had not yet initiated.

Late spring fires have been found to favor the growth of C4 tallgrass species populations relative to C3 graminoids and forb populations (Howe 2000, Engle and

Bidwell 2001). Naturally-occurring fires caused by lightning strikes would, however, have been much more frequent during dry midsummer periods than other seasons (Howe

1995), which would have not favored C4 tallgrasses to the extent that dormant-season fires do. Fire can alter the competitive rankings of species in prairie communities (Suding

2001), resulting in dramatic shifts in community composition depending on the season of the application of fire to a community. Growing season fires in Oklahoma were observed by Engle et al. (2008) to stunt tallgrass populations while promoting forb growth, and

Copeland et al. (2002) found that growing season fires in Illinois savanna promoted the growth of subdominant species while not harming populations of tallgrasses.

Burning the Buffalo Beats site during the spring would help the growth of populations of Andropogon gerardii and Sorghastrum nutans and transition the site towards a more lush tallgrass-dominated condition as observed by Jones (1944). The historic condition of the site, however, may have been of forb domination, as suggested by the high levels of forb phytoliths found in the prairie soils of Buffalo Beats by Kalisz and Boettcher (1990). Midsummer fires would therefore be a more natural form of

58 disturbance, and could transition the prairie toward a more diverse community of forbs while preserving the present large populations of tallgrasses. Heslinga and Grese (2010) found that dominant populations of A. gerardii can hinder species diversity in prairie remnants due to intense competitive exclusion, and may be inhibiting the growth of the state-threatened species Gentiana alba and Eryngium yuccifolium. In the interest of expanding rare species populations, promoting the growth of forb species evenness within the Buffalo Beats prairie could be a priority for future management.

Southern Lens

The southern lens habitat at Buffalo Beats is currently overgrown with populations of Rubus species. Though several prairie species are known to occur there, including the threatened Eryngium yuccifolium and Gentiana alba, the herbaceous community is sparse and dominated by non-prairie species. Tree species are also in abundance; tree seedling diversity and frequency was similar among the southern lens and northern forest plots. Though among the thirteen tree species found in southern lens plots, only Quercus alba was observed in at least half of the plots and with greater than 2 percent mean cover.

The dominance and abundance of woody species within the southern lens, as well as the sparse herbaceous community, is in stark contrast to the plant community of the northern prairie. Efforts to convert the southern lens to a prairie have succeeded in opening the previously closed canopy, but failed to promote the emergence of a prairie species-dominated plant community. Instead, shrub and tree species have emerged and thrived in the newly lit understory. This is similar to the development of the transition

59 zone community following the elimination of mature trees and saplings. In both locations, opening the previously closed canopy was not accompanied with regular fire treatments that would have stymied woody succession and promoted the growth of prairie species populations.

Forest Community

The general trend in the transition zone tree community is one of decreasing species diversity and an increased dominance and importance of Quercus alba in all size classes. The large decreases in saplings and small diameter trees following the implementation of Hardin's (1988) proposed management plan are expected due to repeated 'hack-and-squirt' herbicide treatments of young trees in the area immediately surrounding the prairie zone. Several large Q. alba trees immediately bordering the prairie were also girdled in the time between samplings, which contributed to the decrease in observed density of individuals in larger DBH classes within the transition zone. The increase in basal area of larger trees may have been accelerated by the artificial thinning of individual trees within the transition zone, but within the forest mechanical thinning has not been introduced. Thinning of vulnerable young trees by fire treatments could have contributed to decreases in young tree densities in both forest zones, along with natural loss by overtopping and senescence of shade-intolerant trees. Despite the drop in total number of individual trees, total basal area of trees within the forest has increased. Increases in total forest basal area following thinning is a known phenomenon

(Runkle 1998, Miller 2000, Baldwin et al. 2000), and can increase the vigor of even old- growth trees (Latham and Tappeiner 2002). The removal of young individuals and

60 application of fire has shifted the transition zone towards a more savanna-like community structure, though the canopy remains largely closed.

The forest tree community has changed in a similar manner to the transition zone, though the change towards a Quercus alba-dominated community is more dramatic compared to conditions prior to the implementation of prescribed fire. During the 1980s,

Q. alba was subdominant to several other oak species within the forest, and was not particularly frequent in the understory. Though Q. alba saplings remain infrequent in

2012, large pockets of seedlings have emerged and are second in density only to

Crataegus sp. Sassafras albidum seedlings were not observed at all in plots in 2012, and saplings were also much less dense. Ostrya virginiana was by far the most dense sapling species observed, and was found in every plot sampled for saplings. Ostrya virginiana individuals were noted for having vigorous resprouting, and so could respond quickly to fire treatments better than many forest species that have been reduced in number or entirely extirpated from the forest since the initiation of a fire regime.

Decreases in species diversity and density of individuals would be expected when applying fire treatment to the forest community that existed in Buffalo Beats during the

1980s. Whereas Quercus alba is known for its fire tolerance, species such as Juglans nigra, Acer rubrum, and Fraxinus americana are not known for effectively withstanding fire applications, and so have most likely been removed from the forest surrounding

Buffalo Beats by fire. Most tree species present in the 2.5-9.9 cm DBH class in the 1984 sampling were infrequent, had few individuals, and were not present in the larger size classes, and so did not have large populations or robust individuals that could withstand repeated occurrences of fire. Larger individuals could be expected to survive reasonably

61 well when exposed to repeated low-intensity understory fires, and the Quercus alba population in particular would be at an advantage as previous competitors were removed from the community.

Throughout the extent of the former prairie peninsula during the 20th century, a climatic trend towards increased moisture has been observed (Grundstein 2009). Though

Quercus and Carya species have historically dominated the savannas and open forests of the prairie peninsula (Brewer and Vankat 2004, Mack and Boerner 2004, Hutchinson et al. 2005, McClain et al. 2007, Kilburn et al. 2009), fire suppression and increased moisture have allowed for Acer and Ulmus species to emerge as new dominant canopy species across forests of the Midwest (Ebinger and McClain 1991, Cowell and Jackson

2002). Our results indicate that dormant-season fire treatments have succeeded in preventing that trend from occurring in the forest surrounding Buffalo Beats.

The forest at Buffalo Beats has been consistently dominated by Quercus and

Carya species since the 1960's (Wistendahl 1975), but by the 1980's the understory tree community was becoming increasingly dominated by Cornus florida and Sassafras albidum. Quercus prinus was present in relative abundance in the seedling and sapling layers, but other species of Quercus were more rare in the understory than found previously (Hardin 1988). Similar slowdowns in oak regeneration in historically oak- dominated forests have been observed (Ebinger and McClain 1991, McCarthy and Bailey

1996, Cowell and Jackson 2002), and lack of fire has been cited as a probable cause.

Albrecht and McCarthy (2006) observed that a single instance of fire may not be sufficient to reverse succession of fire-intolerant tree species into oak-hickory forests, and that repeated application of fire may be necessary to promote oak regeneration. Our

62 results confirm that repeated fire treatment can promote the re-establishment of Quercus species, particularly Quercus alba, to the understory of a forest previously dominated by non-fire tolerant tree species.

Soil Conditions

The mean pH values calculated across the prairie, transition, and forest plots were not significantly different (P > 0.05), largely due to a wide variance in values measured from individual plots. The soil conditions of each zone were very heterogeneous. Within the prairie itself, pH was circumneutral in the central four plots and decreased as plots approached the edge of the forest. In prior reports of pH from Buffalo Beats, only averages were reported; significant differences between the zones were not established.

Thus, pH levels may not have shifted greatly in the 50 years since studies began at

Buffalo Beats, and in fact when comparing individual pH values along the East-West gradient to those of Wistendahl (1975), there is no clear shift in values.

The restriction of relatively high pH values within the prairie to the central four permanent plots is worrying, as it suggests that conditions of surrounding soils have been influenced towards a more acidic forest-like state. Whether the shift towards acidity occurred in recent decades or prior to measurements in the 1960's is uncertain, because we do not have a record of where within the prairie pH was sampled in the past. The mean pH of the transition and forest zone, however, increased from 4.9 in 1964 to 5.5 in

2012, and the pH of the transition increased slightly from 5.6 to 5.8. Whether this change is significant cannot be determined due to lack of surviving raw data from previous

63 studies, but given the shift in forest community structure towards a fire-conditioned state, it is certainly possible that the forest soils are also changing due to fire.

The results of the texture analyses confirm the findings of McClenahen and

Houston (1990) of a clay lens in southern Buffalo Beats, and provide a quantitative comparison to the soils of the northern prairie. While most of the soils sampled on the lens do not contain the same level of clay as in the northern habitat, they are still distinct from the shale-derived soils in the surrounding forest.

The significant differences in soil C:N ratios observed among the prairie, transition, and forest zones demonstrate that the three zones are still yet distinct. The soil conditions of the prairie, with a C:N ratio near 10 and near circumneutral pH, are in a state conducive to the growth of prairie species. The soils of the transition, much like its plant community, remain as a gradient between the prairie and forest conditions.

The similarity of soil conditions (texture, pH, C:N) of the transition zone and southern lens, in addition to their similar plant community physiognomy, suggests that they are in similar states of community development between prairie gap and closed forest. The two locations also possess thick infestations of Rubus invading areas previously shaded by large Quercus alba trees.

Soil Seedbank

Among the species that germinated from seedbank samples of the northern site that were not present aboveground during the growing season in 2012, Erechtites hieraciifolia, Physalis sp., and Phytolacca americana were all observed in the surrounding transition or forest during herbaceous plot sampling. None of these species

64 were observed by Wistendahl (1975) or Hardin (1988), and are not considered 'prairie species'. They could become yet more additions from the forest into the prairie if not sufficiently inhibited. Far fewer species were found in the seedbanks of all communities than were observed during aboveground vegetation sampling. This could be due to dispersal or sampling limitations. Furthermore, yet fewer species were observed within the later samples, demonstrating the flush of germination in the spring. Still, some species were observed among the May samples that did not emerge from March samples.

Willand et al. (2013) found that within restored prairies, plant community structure largely reflects the composition of existing buds within the soils of the prairies.

Dominant bunchgrasses like Andropogon gerardii exert great competitive pressure on potential colonizers (Heslinga and Grese, 2010), and the competitive advantages of A. gerardii and Sorghastrum nutans may be effectively preventing invading seeds from establishing.

It is interesting that few woody species germinated from the seedbank samples of all four communities. No seedlings of Rubus species germinated, which is surprising considering the dominance of the genus in the southern lens. Many soil samples from the southern lens were gathered from underneath Rubus patches, and the lack of germinated

Rubus seeds from those samples may be due to a lack of successful seed dispersal at the site and growth of the populations are largely due to vegetative reproduction. However, effects of sampling and germination conditions cannot be ruled out.

CONCLUSIONS

The plant communities of the three vegetative zones of the historical Buffalo

Beats site have all shifted in composition since last quantified in the 1980's. Due to the introduction of fire, the Quercus alba population within the forest and transition has grown across several age classes, and is emerging as the dominant tree species in the studied area. Within the prairie, key species have been successfully preserved, and prairie species as a group have rebounded since the initiation of USFS management.

The structure of the plant community of Buffalo Beats has likely fluctuated a great deal throughout its history. By its very nature as a canopy opening, it relies upon forces of disturbance to remain in existence. Natural tree fall due to extreme weather events does occur in the area, and likely plays an important role in the structure of the tree community immediately surrounding the prairie opening. The age structure of the forest community immediately surrounding the Buffalo Beats prairie suggests a dynamic condition of tree encroachment and loss for the past several hundred years (McClenahen and Houston 1998).

Selective removal of trees by girdling and herbicide has been effective at expanding the open canopy space needed to expand the prairie, but the newly open canopy has allowed for invasion of Rubus and did not expand the prairie community.

Removal of canopy cover should be coupled with fire application to prevent the encroachment of shrub species and tree seedlings, and allow prairie species present in the seedbank to emerge and grow without competition from woody species. The expansion of Rubus could be curtailed with a two-step removal process using herbicide and prescribed fire. A targeted application of glyphosate to the large swaths of Rubus in the

66 transition zone and southern lens would kill most of the standing biomass, and provide a large mass of easily ignitable fuel for a burn in the same year (or shortly thereafter).

Burns at Buffalo Beats in the past have reportedly been spotty, with one during the

1990’s in particular noted for not achieving desirable intensity. Converting the majority of standing Rubus biomass into dry fuel should achieve both a satisfactory burn of the northern and southern sites as a whole as well as eliminate more Rubus individuals than herbicide alone or fire alone would accomplish.

The loss of prairie species from Buffalo Beats is especially problematic because of the rarity and isolation of the site. Few locations within southeastern Ohio as a whole could provide new propagules to reintroduce lost species such as Liatris cylindracea to the Buffalo Beats prairie. Reintroduction is, however, not impossible. Buffalo Beats is widely regarded as a local treasure by researchers and conservationists within Athens

County, and has stimulated interest in prairie restoration throughout the County. This has included efforts to establish new populations of many prairie species in nearby parks and protected areas, including the state-threatened Gentiana alba and the potentially threatened Eryngium yuccifolium. These nearby sites could serve as refugia and source populations for prairie species to be reintroduced to areas where they were formerly extirpated, either by natural dispersal or artificial seeding.

Future management of the Buffalo Beats site should include more frequent fire applications. Similar restoration projects have shown a significant increase in prairie species dominance with more frequent fires (McClain et al. 2007). Given that several

Quercus alba individuals currently growing at Buffalo Beats have persisted at the site since prior to the 19th century (McClenahen and Houston 1998) and the strong

67 regeneration of Q. alba within the Buffalo Beats forest, the site could be regarded not only as a quality remnant prairie, but also as a potential old-growth forest site and useful case of Quercus alba regeneration through consistent fire application.

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APPENDIX

Table 13. Shorthand labels of plant species observed at Buffalo Beats during 50 years of study for use in graphical visualizations of community structures.

Species Label Species Label Agrimonia pubescens AGPU Hieracium sp. HISP Ambrosia artemisiifolia AMAR Ipomoea pandurata IPPA Amphicarpaea bracteata AMBR Krigia biflora KRBI Andropogon gerardii ANGE Lespedeza hirta LEHI Antennaria plantaginifolia ANPL Lespedeza repens LERE Aster cordifolius ASCO Lespedeza virginica LEVI Aster laevis ASLA1 Liatris aspera LIAS Aster lateriflorus ASLA2 Lobelia spicata LOSP Aster patens ASPA Melilotus alba MEAL Boehmeria cylindrica BOCY Monarda fistulosa MOFI Bromus purgans BRPU Ostrya virginiana OSVI Calystegia sepium CASE Parthenocissus quinquefolia PAQU Cardamine flexuosa CAFL Phlox pilosa PHPI Carex sp. CASP Phlox sp. PHSP Carpinus carolinianus CACA Phlox subulata PHSU Ceanonthus americanus CEAM Plantago major PLMA Convolvulus arvensis COAR Poa sp. POSP Coreposis tripteris COTR Potentilla canadensis POCA Crataegus sp. CRSP Potentilla simplex POSI Danthonia spicata DASP Ranunculus hispidus RAHI Desmodium canadense DECA1 Rosa carolina ROCA Desmodium canescans DECA2 Rubus allegheniensis RUAL Desmodium nudiflorum DENU Scutellaria incana SCIN Desmodium paniculatum DEPA Silphium trifoliatum SITR Desmodium sp. DESP Smilax rotundifolia SMRO Dichanthelium dichotomum DIDI Solidago bicolor SOBI Dichanthelium latifolium DILA Solidago caesia SOCA Dichanthelium sp. DISP Solidago juncea SOJU Elymus hystrix ELHY Solidago rigida SORI Eryngium yuccifolium ERYU Solidago sp. SOSP Eupatorium rugosum EURU Sorghastrum nutans SONU Euphorbia corollata EUCO Symphyotrichum laeve SYLA1 Eurybia sp. EUDI Symphyotrichum lateriflorum SYLA Galium circacaezans GACI Symphyotrichum lowrieanum SYLO Galium concinnum GACO Symphyotrichum patens SYPA Galium mollugo GAMO Toxicodendron radicans TORA Gentiana alba GEAL Vicia caroliniana VICA Geranium maculatum GEMA Viola sp. VISP1 Gillenia stipulata GIST Vitis aestivalis VIAE Helianthus divaricatus HEDI Vitis sp. VISP2 Helianthus hirsutus HEHI Zizia aptera ZIAP Helianthus strumosus HEST

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