William N. Grafton

A COMPARISON OF PLANT COMMUNITIES IN MITIGATION AND REFERENCE WETLANDS IN THE MID-APPALACHIANS

Wetland destruction has plagued the U.S. for decades, but the need to compensate for these losses has only been embraced within the last 20 years. Because so many compensatory mitigation wetlands have been created, there is a need to assess the function of these valuable ecosystems relative to natural wetlands. The goal of this study was to evaluate the functional equivalency of mitigation wetlands in West Virginia in supporting hydrophytic plant communities. A series of nested quadrats was used to compare plant community structure among eleven mitigation and four naturally occurring reference wetlands. For all species combined, mean total percent cover across all sampling quadrats per wetland was similar between mitigation and reference wetlands. Species richness, evenness, and diversity were greater in mitigation than in reference wetlands. Mean weighted averages of plant communities calculated using cover values and wetland indicator status were similar between mitigation and reference wetlands. There were, however, major differences in species composition. Mitigation sites tended to have more pioneer species, non-native dominants, and species with relatively lower conservation quality. Ordination analyses suggested that compositional differences become smaller as mitigation sites age. Both mitigation and natural wetlands met criteria for hydrophytic vegetation according to the 1987 U.S. Army Corps of Engineers Wetland Delineation Manual. These data suggest that the mitigation wetlands investigated in this study adequately support hydrophytic vegetation and appear to be developing vegetation similar to reference standards.

Using two classification schemes to develop vegetation indices of biological integrity for wetlands in West Virginia, USA

Bioassessment methods for wetlands, and other bodies of water, have been developed worldwide to measure and quantify changes in “biological integrity.” These assessments are based on a classification system, meant to ensure appropriate comparisons between wetland types. Using a local site-specific disturbance gradient, we built vegetation indices of biological integrity (Veg-IBIs) based on two commonly used wetland classification systems in the USA: One based on vegetative structure and the other based on a wetland’s position in a landscape and sources of water. The resulting class-specific Veg-IBIs were comprised of 1–5 metrics that varied in their sensitivity to the disturbance gradient (R2 = 0.14 − 0.65). Moreover, the sensitivity to the disturbance gradient increased as metrics from each of the two classification schemes were combined (added). Using this information to monitor natural and created wetlands will help natural resource managers track changes in biological integrity of wetlands in response to anthropogenic disturbance and allows the use of vegetative communities to set ecological performance standards for mitigation banks.

The vascular flora of roadside habitats in West Virginia, USA.

ABSTRACT  In order to provide vegetation managers with information on roadside habitats in West Virginia, a statewide roadside vegetation study was conducted in 2000. The vegetation along nearly 1,500 km of four-lane highways was sampled in 339 randomly selected 20 m wide strip plots. An index of occurrence class (IOC) for each species was calculated using the product of the percent frequency of occurrence and relative abundance. A total of 467 species were documented, 325 of which were native. Seven families accounted for more than 50% of all species. When ranked on the basis of total IOC values, 15 of the top 25 species were introduced. Mean IOC values for introduced species (6.0) were significantly greater than native species (4.3, p = 0.0013). We propose that despite initial variability of landform, parent material, forest cover types, and climate, the relative similarity of species composition along the highways we sampled was the result of the physical and biological disturbances associated with initial construction (cuts and fills), and postconstruction seeding and vegetation management efforts.

Vegetation Patterns within the Lower Bluestone River Gorge in Southern West Virginia

Abstract Seven forest community types are described for a 2,100 ha study area in the lower Bluestone River Gorge in southern West Virginia. This is a remote, steeply sloped area, part of a large natural area that provides habitat to several plants not known elsewhere in the state. It is an example a topographic setting underrepresented in quantitative studies of forest vegetation in the region. Forest types were derived from cluster analysis of quantitative data on composition and structure of large tree (dbh ≥ 10 cm) strata obtained from 51 0.1 ha quadrats, the majority of which were included in a series of eleven transects that extended from the bottom of the gorge to a point near the rim. Multi-response permutation procedures verified the community classification. Mean topographic and soil characteristics for each community type were then compared using analysis of variance. The community types recognized conform to forest cover-types widely distributed throughout the region. Non-metric dimensional scaling indicates that topographic variables have a strong influence on the distribution of community types within the gorge. However, due to the presence of limestones and calcareous shales at midslope position, variation in soil nutrient quality tended to account for more of the variation in vegetative composition. Various species of Quercus were prominent overstory trees in six of seven community types. The continued dominance of Quercus spp. seems most likely on the more nutrient poor, west- southwest-facing sites at mid- to upper-slope positions. On more mesic, better quality growing sites, Acer saccharum and A. rubrum exhibit overwhelming importance in the understory and are likely to increase in importance.

White-tailed deer florivory influences the population demography of Polemonium vanbruntiae

Abstract White-tailed deer (Odocoileus virginianus Zimm.) may influence reproduction and dispersal of plant species through herbivory of flowering stems. We examined the effects of white-tailed deer herbivory on the seed production of Bog Jacob’s-ladder (Polemonium vanbruntiae Britt.), a facultative wetland plant considered rare throughout its range. We monitored life-stage transitions in 10 local populations in Canaan Valley, West Virginia, from 2005–2007, modeled the population growth rates, and estimated extinction rates for each population accounting for the loss of seeds due to white-tailed deer florivory. Seed loss due to consumption of flowering stems ranged between 0 and 96% within individual populations ( = 52 ± 4.5%). A significant difference in seed production occurred between browsed ( = 0.6 ± 0.18) and unbrowsed ( = 24 ± 1.43) plants. Predicted seed loss was significantly higher ( = 57 ± 19%), where no hunting was allowed, than where deer hunting occurred ( = 40 ± 18%). The observed levels of white-tailed deer florivory have the potential to significantly reduce population growth rates (p < 0.0001). Although white-tailed deer florivory may not increase local population extinction rates, loss of seed production may result in a loss of the potential for colonization of new patches.

Rare Plants of Canaan Valley, West Virginia

Abstract Canaan Valley (hereafter, the Valley), in northeastern West Virginia, supports large areas of wetland, upland forest, and upland non-forest habitats at relatively high elevations, providing potential habitat for a variety of rare plant species. The presence of 54 species of plants considered to be rare and of conservation concern in West Virginia plus 22 watchlist species has been confirmed in the Valley. No federally listed threatened or endangered plants have been found. One of the rare species is the globally critically imperiled Platanthera shriveri (Shrivers Frilly Orchid) and 4 are globally vulnerable—Gymnocarpium appalachianum (Appalachian Oak Fern), Hypericum mitchellianum (Blue Ridge St. Johnswort), Euphorbia purpurea (Glade Spurge), and Polemonium vanbruntiae (Bog Jacobs-ladder). Rare plants are found throughout the Valley; 80% occur in wetlands, and a significant assemblage is associated with wetlands on Greenbrier Limestone. Globally rare species are Appalachian endemics, but 41 of the Valleys rare and watchlist plants are primarily northern in distribution. Extant native populations are known in West Virginia only from the Valley for 3 species—Carex atherodes (Awned Sedge), Gentianopsis crinita (Greater Fringed Gentian), and Viburnum trilobum (American Cranberry-bush)—and a significant portion of all known West Virginia occurrences for at least another 16 species are in the Valley. Several rare plant species grow in multiple places in the Valley, but others are known from only 1 or 2 sites and are quite vulnerable. Non-native insect pests threaten Abies balsamea (Balsam Fir) and Fraxinus nigra (Black Ash). There are a number of threats to the Valleys rare plants: invasive plants, especially Typha latifolia (Broadleaf Cattail), Iris pseudoacorus (Yellow Flag), Phalaris arundinacea (Reed Canarygrass), and Microstegium vimineum (Japanese Stiltgrass); browsing by Odocoileus virginianus (White-tailed Deer); residential development; hydrologic changes to wetlands; and climate change.