Estimates of above-ground phytomass and nutrients in the understory vegetation in an Appalachian oak forest in Virginia

Destructive sampling was undertaken to estimate the contribution of the herb stratum and shrub stratum to above-ground phytomass and nutrients (N, P, K, Mg and Ca) in four different vegetation types in an Appalachian oak forest in southwestern Virginia. The study area is located at midslope on the southeast aspect of Potts Mountain in four non-contiguous compartments which are to be clearcut and whole-tree harvested in the near future. A partial random sampling scheme was utilized to select 20 x 20m study areas, within which 48 1 x 1 m and 16 5 x 5 m herb and shrub stratum plots were nested respectively. Statistical tests indicated that significant differences in above-ground phytomass and nutrients exist between vegetation types in both strata. The trend is towards greater amounts of understory vegetation on progressively drier sites. Total amounts (kg/ha) of nutrient elements show a similar trend. In contrast, nutrient element concentrations show a reverse trend, with higher concentrations of nutrients found on the more mesic sites. Ordination techniques were utilized to investigate differences in nutrient concentrations among species. Species groupings derived from the ordinations substantiated the sorting of vegetation types along a moisture gradient. Regression equations for individual