Canopy Gap Dynamics in a Second-Growth Appalachian Hardwood Forest in West Virginia

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) m(2). 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.