C. Reed Rossell

Effects of Deer Browsing on Native and Non-native Vegetation in a Mixed Oak-Beech Forest on the Atlantic Coastal Plain

Abstract We studied the effects of browsing by Odocoileus virginianus (white-tailed deer) on the native and non-native vegetation in a mixed oak-beech forest in Rock Creek Park, Washington, DC. We compared the thickness and cover of vegetation up to 2 m in height, and species richness of native and non-native plants in 17 exclosed (1 × 4 m) and 17 control plots from 2001–2004. Over the four-year period, foraging by deer suppressed the thickness of vegetation ≤ 1 m in height, reduced the cover of herbaceous, woody, and native plants, and generally decreased the species richness of native and woody plants. Browsing had no effects on the species richness of non-native plants, but generally reduced the prevalence of Celastrus orbiculatus (oriental bittersweet). Of the dominant canopy species, browsing affected Quercus spp. (oak) regeneration, but had no apparent effects on Fagus grandifolia (American beech). These results indicate that white-tailed deer are having a detrimental effect on the structure and species richness of native plants in this forest, and as a consequence, diminishing the value of the habitat for wildlife. In addition, white-tailed deer may help control the spread of oriental bittersweet in forest interiors, particularly where this species occurs at relatively low levels. If deer browsing is left uncontrolled in this forest, we predict that its future composition will shift towards one with fewer species and one dominated almost exclusively by American beech.

Microhabitat Selection by Eastern Box Turtles (Terrapene c. carolina) in a North Carolina Mountain Wetland

Abstract We investigated microhabitat selection by Terrapene carolina carolina in a North Carolina mountain wetland. We monitored a total of 21 radio-tagged turtles in 1997 and 1998. Turtles were located at least weekly from mid-May until they entered their overwintering sites. Microhabitat characteristics were quantified at each turtle location and at a corresponding random location < 25 m away. Weather varied during the study: 1998 was much hotter and drier than 1997. Microhabitat did not differ between males and females, except that females selected form locations with greater amounts of exposed soil. Overall, turtles constructed forms in areas that were more humid than the surrounding environment. Box turtles also used habitats with lower surface temperatures and higher humidity levels than the surrounding environment, particularly during hot and dry periods. This likely helped them regulate body temperature and prevent desiccation. During the summer of 1997 and all monitoring seasons in 1998, turtles were located at sites with moderate canopy cover and less understory plant cover than expected. Sites with less understory cover may have greater air circulation than those with more cover, thus allowing turtles to dissipate heat more rapidly. Amounts of woody debris, leaf litter, and canopy cover at turtle locations were similar to those available in the surrounding environment. Our results indicate that the attributes most important for defining the microhabitat of T. carolina (surface temperature, relative humidity, and understory plant cover) are related to thermoregulation and minimizing water loss.

Impacts of Beaver Foraging on the Federally Threatened Virginia Spiraea (Spiraea virginiana) along the Cheoah River, NC

Abstract Spiraea virginiana (Virginia Spiraea) is a federally threatened shrub endemic to the southern Blue Ridge and Appalachian Plateau physiographic provinces. Observations along the Cheoah River, where the largest population of S. virginiana occurs in North Carolina, indicate that Castor canadensis (Beaver) feed on S. virginiana. However, the effects of Beaver foraging on this imperiled shrub are unknown. To address this issue, we randomly located 50 belt transects (25 m × 2.5 m) along the center of the scour zone of the Cheoah River and assessed all basal stems (<2.5 cm in diameter) of woody plants for evidence of browsing by Beaver. We recorded a total of 4963 basal stems, consisting of 59 species. Of those stems, 14.7% were browsed by Beaver. Spiraea virginiana accounted for 3.5% of the total basal stems and ranked fourth in the total number of stems browsed with 8.8%. After adjusting for transect effect, S. virginiana ranked second as a preferred forage species, with 32.0% of its stems browsed. This study suggests that overall browse levels of this community are relatively low compared to other communities inhabited by Beaver because of the high-gradient and turbulent nature of the Cheoah River. Our findings provide strong evidence that S. virginiana is an important food to Beaver, and as a consequence, Beaver foraging has the potential to affect this population. Although more information is needed to determine the long-term impacts, we suspect that in the short-term, S. virginiana may benefit from the levels of browsing found in this study. Field observations suggest that Beaver foraging stimulates asexual reproduction of S. virginiana by inducing rhizomatous growth. Beaver also may help S. virginiana with dispersal, as fresh cuttings are often left at feeding sites and then may be transported downstream for rooting.

Attributes of Shelters Selected by Eastern Hellbenders (Cryptobranchus a. alleganiensis) in the French Broad River Basin of North Carolina

Abstract We investigated the attributes of shelters used by Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) in two 500-m stretches of the French Broad River basin in North Carolina during June 2010. We quantified attributes at each Hellbender shelter and at a corresponding unoccupied shelter located <25 m away to determine whether the attributes selected differed from those available in the surrounding environment. We identified 41 Hellbender shelters, each occupied by a single animal. Hellbenders selected shelters that had larger cover rocks and deeper cavities than the unoccupied shelters. No other attributes differed between occupied and unoccupied shelters, and there were no significant relationships between total length of Hellbenders and size of the cover rock or cavity depth. All Hellbender shelters were formed by large rocks with flat bottoms. Most had a single entrance that was oriented downstream and a cavity floor consisting of sand and gravel. Shelters were generally located in shallow, fast-flowing water with <10% of their surface area embedded in the substrate. Our results suggest that Hellbenders prefer shelters with attributes that maximize cavity space. Larger cavities likely provide greater protection from predators and greater concealment from sunlight. In addition, larger cavities allow more space for Hellbenders to rock back and forth to maximize oxygen uptake through their skin during periods of low flow when oxygen levels drop.

Attributes of Rock Crevices Selected by Allegheny and Eastern Woodrats in the Zone of Contact in the Appalachian Mountains of North Carolina

Abstract We investigated the attributes of rock crevices selected by Allegheny (Neotoma magister) and eastern woodrats (N. floridana haematoreia) in their zone of contact in the Appalachian Mountains of North Carolina. In North Carolina, N. magister and N. f. haematoreia both occur in rocky habitats above 300 m, and are listed as species of special concern. We studied 14 active sites (N. magister: n  =  9; N. f. haematoreia: n  =  5) where woodrats had been captured 1 y prior to our study and identified to species using the mitochondrial DNA D-loop analysis. At each site, we measured the attributes of 10 crevices used by woodrats and 10 corresponding random crevices located < 15 m from each used crevice. Neotoma magister and N. f. haematoreia selected crevices with larger dimensions (height, width and depth) and more internal fissures (openings >5 cm in diameter) than those available in the surrounding environments. All crevices used by N. magister (n  =  90) and N. f. haematoreia (n  =  50) were dry. Neotoma magister were more specialized than N. f. haematoreia, as they selected crevices that were south-facing. These results suggest that both N. magister and N. f. haematoreia are habitat specialists in the southern Appalachians, preferring crevices with larger dimensions and more internal fissures to enhance their protection against severe weather and predators. The preference for south-facing crevices by N. magister suggests that they may be better adapted at surviving colder climatic conditions, thus enabling them to inhabit higher elevations in the mountains. Based on these specialized habitat preferences, we suggest that suitable rock crevices may be a limiting factor to both species in the southern Appalachians. In addition, the similarity in attributes of rock crevices selected by these species suggests that habitat is not a factor that will prevent hybridization between these species where they co-occur in the mountains of North Carolina.

Description of Rich Montane Seeps and Effects of Wild Pigs on the Plant and Salamander Assemblages

Abstract Rich Montane Seeps are rare wetland communities endemic to high elevations of the southern Appalachian Mountains. Comprehensive data on the flora and fauna associated with these communities are lacking. Recent surveys indicate the rooting by nonnative wild pigs (Sus scrofa) may be affecting these communities. This study describes the abiotic and biotic features of Rich Montane Seeps across the Great Smoky Mountains National Park (GSMNP), investigates the effects of wild pigs on plant and salamander communities, and examines habitat attributes that influence pig disturbance. In our study a Rich Montane Seep was defined as any wetland with sheet flow occurring in hardwood forests above 1067 m. Pig disturbance and habitat attributes were measured in 1-m2 plots placed at 5 m intervals along a transect located on the longest axis of each seep. Habitat attributes measured included plant cover, plant richness, surface water, substrate, down woody debris, and shrub and tree densities (sampled in 3 m diameter circular plots). Salamanders were also sampled in each 1-m2 plot, identified to species when possible, and classified as larva, juvenile or adult. Thirty-five seeps, representing 24 drainages, were sampled. Rich Montane Seeps were characterized as small, linear wetlands with an open canopy, dense herbaceous vegetation, and few trees or shrubs. One hundred eighty species of plants (132 herbs, 35 shrubs, and 13 trees) and 10 species of salamanders (97 adults, 204 juveniles, 14 larvae) occurred in seeps, including eight plant species and three salamander species of conservation concern. Forty-nine percent of seeps and 54% of drainages had evidence of pig disturbance. Disturbance within seeps varied from 0-96% (mean  =  21%). Wild pigs negatively affected plant cover and plant richness. Wild pigs also had a negative effect on salamander surface density, but to a lesser extent than on plants. Amount of pig disturbance was negatively associated with slope. These results strongly suggest wild pigs are threatening the ecological integrity of Rich Montane Seeps across their range by negatively affecting the plant and salamander communities, particularly in seeps occurring on flat terrain.

Forage Selection of Native and Nonnative Woody Plants by Beaver in a Rare-Shrub Community in the Appalachian Mountains of North Carolina

Abstract Castor canadensis (Beaver) is a selective forager that can modify the species composition and structure of plant communities. However, no studies have examined the use of woody plants by Beaver in temperate forests that contain a dominant nonnative plant. We investigated foraging of woody plants by Beaver in a riparian shrub community that is dominated by both native and nonnative species, including the federally threatened shrub Spiraea virginiana (Virginia Spiraea). We established 48 random, 25-m transects along a 12-km reach of the Cheoah River in the Appalachian Mountains of North Carolina. We sampled woody plants every 5 m using a modified point-centered quarter method to estimate relative abundance and to quantify browsing by Beaver. We used a mixed linear model to determine Beaver forage selection on the 9 most abundant plant species and Virginia Spiraea. We recorded 984 plants of 58 woody species (55 native, 3 nonnative). Beaver browsed 24% of the woody species sampled and 8% of all stems. This finding suggests that the overall effects of browsing in this community were relatively low, likely because of the high gradient and turbulent nature of the Cheoah River. Relative stem abundance and location along the river did not differentially affect local levels of browsing. However, Beaver were selective foragers at both the species and individual-plant level. Of the 9 most abundant species, Carpinus carolinana (Musclewood), Liquidambar styraciflua (Sweetgum), and Alnus serrulata (Tag Alder) were selected most often; Lindera benzoin (Spicebush), Virginia Spiraea, Cornus amomum (Silky Dogwood), and Ligustrum sinense (Chinese Privet) were moderately selected. Least frequently selected species were Rhododendron maximum (Rosebay Rhododendron), Leucothoe fontanesiana (Doghobble), and Xanthorhiza simplicissima (Yellowroot). Browsing appeared to have a positive effect on both the invasive nonnative shrub, Chinese Privet, and the rare Virginia Spiraea by stimulating asexual reproduction and inducing plants to spread through suckering. This study demonstrates the importance of understanding the reproductive strategies of woody plants when gauging the community-wide effects of foraging by Beaver, particularly when an invasive plant species is present.

Comparison of Relative Abundance and Microhabitat of Desmognathus organi (Northern Pygmy Salamander) and Desmognathus wrighti (Southern Pygmy Salamander) in North Carolina

Abstract There are currently no quantitative studies describing the habitat of Desmognathus organi (Northern Pygmy Salamander) and D. wrighti (Southern Pygmy Salamander). We investigated the relative abundance and microhabitat selection of Northern Pygmy Salamander and Southern Pygmy Salamander in 3 forest types of different elevations across the mountains of North Carolina during the summer of 2015. We conducted 2-h time-constrained searches at 4 sites in Picea rubens (Red Spruce) —Abies fraseri (Fraser Fir) forests, northern hardwood forests, and mountain cove forests for each species. We quantified microhabitat characteristics at each pygmy salamander location and at a corresponding random location 2–30 m away. We captured a total of 98 pygmy salamanders (D. organi = 41, D. wrighti = 57): 52 in spruce—fir forests, 26 in northern hardwood forests, and 20 in cove forests, and recorded 655 other salamanders representing 15 species. Relative abundance of pygmy salamanders was greater in spruce—fir forests than in cove forests, but was not significantly different between spruce—fir and northern hardwood forests. Microhabitat did not differ between Northern Pygmy Salamander and Southern Pygmy Salamander for any of the variables examined, except for soil moisture, which was greater at Northern Pygmy Salamander locations and may have been a spurious result. We observed pygmy salamanders almost exclusively beneath wood cover-objects, and size of cover objects did not differ from the size available in the surrounding environments. Total area of small-sized down woody debris (DWD) and total area of large-sized DWD were the only variables associated with the presence of pygmy salamanders, suggesting that pygmy salamanders avoid predation and interspecific competition by selecting sites that minimize encounters with larger salamanders.

Habitat Characteristics of Spiraea virginiana Britton, a Federally Threatened Riparian Shrub, in North Carolina

ABSTRACT  We studied the habitat characteristics of Spiraea virginiana Britton (Virginia spiraea), a federally threatened riparian shrub, along eight rivers in western North Carolina. Comparisons between plots with and without S. virginiana revealed that S. virginiana plots were on steep, south-facing slopes and had a higher percentage of large substrate, lower herbaceous and vine cover, higher non–S. virginiana shrub density, lower tree influence, and higher visible sky than control plots. When relating these habitat attributes to the presence/absence of S. virginiana using conditional logistic regression, only substrate size and non–S. virginiana shrub density had significant effects on S. virginiana presence. Principal components analysis (PCA) of all plots (S. virginiana and control) found S. virginiana plots separating from controls that had higher vine and herb cover and lower non–S. virginiana shrub density and slope. Spiraea virginiana plots at the Cheoah River separated from other sites by having greater substrate size and tree influence, and lower visible sky and herb cover. Regression analysis between S. virginiana volume and PCA axes (of plots with S. virginiana only) indicated that volume increased with increasing small substrate, visible sky and non–S. virginiana shrub density, but decreased with increasing tree influence, herb and vine cover, and decreasing slope. Spiraea virginiana restoration efforts should focus on habitats with the attributes described in this study to favor its presence. To ensure S. virginiana vigor, competition from trees, non–S. virginiana shrubs, vines and herbs, especially aggressive nonnative species, should be reduced.