We examined canopy gaps on the 3,100 ha West Virginia University Research Forest (WVURF), a 70–80 year-old, second-growth, Appalachian hardwood forest near Morgantown, West Virginia. The objectives of this study were: (a) to describe gap characteristics (size, age, fraction, regeneration and gap-makers) of the forest as a whole, and (b) to assess whether gap characteristics varied by slope position (cove, midslope, ridge), slope aspect (NE, NW, SE, SW), and forest type (cove hardwood, mesic oak, xeric oak). Sixty transects were established, with a total length of 22,043 m. Eighty canopy gaps were identified. Average gap size was 98.6 (±134.17) m². Gap age ranged from 2–29 years old with a mean age of 16.4 (±6.3) yrs. Overall, 2.7% of the forest was composed of gaps. There were no differences in gap size by aspect or slope position. Cove hardwoods had larger gap sizes than mesic and xeric oak forests. There were no differences in gap age based on slope position, aspect, or forest type. Gap fraction did not differ by slope position, but gap fraction was greatest on southeast slopes and in cove hardwoods. Because the WVURF is a young forest in the stem exclusion and early understory initiation stages of development, tree mortality is primarily driven by stand-level competition. Thus, gaps are smaller compared to old-growth forests in the region, where overstory mortality is largely density independent. Almost two-thirds of gap-makers were Quercus spp., while Quercus spp. and Prunus serotina were the most important regeneration within gaps.

A floristic survey of Crowders Mountain State Park, located in Gaston and Cleveland Counties in North Carolina, was conducted from 2010–2011 to document prairie-relict species. In addition, 1-m² quadrats (n = 200) were sampled from four remnant power line rights-of-way/roadside prairie communities in the park to assess community structure. Cover and frequency values were assessed for species within the quadrats and species were also placed into guild groupings. A total of 143 prairie-relict species from 37 plant families were identified for the entire park, 69 (48%) of which were also found in the sampled quadrats. Eighty-three (58%) species were previously undocumented for the park. Summer forbs represented the largest guild at 66 (46%) with several rare and uncommon species for North Carolina, including the North Carolina Rare Symphyotrichum georgianum (Georgia aster) and Echinacea purpurea (eastern purple coneflower). The communities had a combined Floristic Quality Assessment Index (FQAI) of 48.8 and a mean C-value of 4.2. Evidence from this study further suggests that prior to fire suppression prairie/savanna communities were likely once more prevalent in what is now Crowders Mountain State Park.

A 3-yr study was conducted to determine effects from cutting shrubs that were shading a population of Xyris tennesseensis Kral inhabiting a calcareous seepage fen of the Ridge and Valley Ecoregion. Shrubs were cut to ground level on small plots and Xyris flowering, ramet numbers (a ramet is defined as a leaf-producing stem) and seedling numbers were monitored during three post-treatment seasons. Floral visitation was also documented to determine if shrub cutting increased the likelihood of floral visits by insects that might pollinate flowers. In addition, the seed bank of the site was described and quantified. Shrub cutting significantly increased flowering of Xyris on the site, but only for the first two seasons: by the third season flowering declined, likely caused by competition from other herbaceous species responding to the increased light levels. Shrub cutting also significantly increased seedling production, but no significant increase in the number of Xyris ramets was found. Floral visits were significantly more frequent to Xyris flowers located on cut plots. There was no Xyris seed bank. We conclude that cutting shrubs can stimulate Xyris reproduction for a short period but that long term management must balance this benefit with the resulting increased competition from other non-Xyris graminoids. Management of the fen should strive for a mosaic of microhabitats with varying degrees of woody vegetative cover and exposed mineral soil.

Elevated atmospheric carbon dioxide concentration ([CO₂]) alters the physiology, growth, and development of plants. These changes in plant functioning are likely to impact the relationship between some plant pathogens and their hosts. This study examined the interactive effects of elevated [CO₂] and the economically important, xylem-limited bacterial pathogen Xylella fastidiosa Wells et al. on the physiology and growth of Quercus rubra L. (red oak) seedlings. We hypothesized that growth at elevated [CO₂] would ameliorate the negative consequences of infection on Q. rubra growth and physiology. Oak seedlings were inoculated with a natural strain of X. fastidiosa and grown under “ambient” (400 ppm) and “elevated” (1,000 ppm) [CO₂] for 24 wk. Gas exchange, plant growth, and biomass allocation were measured to determine if elevated [CO₂] alleviated the severity of X. fastidiosa–induced water stress. Xylella fastidiosa infection decreased photosynthesis, stomatal conductance, and transpiration, as well as leaf area and total biomass. Although photosynthesis increased in both noninfected and X. fastidiosa–infected plants grown at elevated [CO₂], the lack of a significant [CO₂] × infection interaction indicated that elevated [CO₂] did not ameliorate the effects of X. fastidiosa infection on leaf-level physiology. Additionally, photosynthetic increases at elevated [CO₂] did not translate to relief of infection symptoms at the whole-plant scale. The findings of this experiment did not support the hypothesis that growth at elevated [CO₂] ameliorates the negative consequences of X. fastidiosa infection on seedling physiology and growth. Future studies should continue to explore the interactive effects of [CO₂] and infection by X. fastidiosa on plant performance.

Valentine, James and Chris Bolgiano. 2011. Southern Appalachian Celebration: In Praise of Ancient Mountains, Old-Growth Forests, & Wilderness. The University of North Carolina Press, Chapel Hill, North Carolina. 136 p. Hardcover, $35.00. ISBN 978-0-8078-3514-2.