PATCH-SIZE EFFECTS ON EARLY SUCCESSION IN SOUTHERN APPALACHIAN FORESTS

Four sizes of forest openings (0.016, 0.08, 0.4, and 2.0 ha) were established to examine the effects of disturbance size on early successional community structure and function. Solar radiation, soil temperature, and air temperature were all higher in large openings than small openings and increased from edge to center of disturbance patches. Aboveground net primary productivity (NPP) was 3-4 times as high in large (2.0 ha) as small (0.016 ha) openings, presumably in response to greater light availability in large patches. Stump and root sprouts of tree species accounted for the largest fraction of NPP in all patch sizes. Herbs, vines, shrubs, advance regeneration trees, and tree seedlings had progressively smaller NPP, respectively. Vegetation biomass reached 0.7-2.6% of undisturbed forest levels and aboveground NPP reached 17-58% of forest levels by the 2nd yr after cutting. Plant species richness was generally higher in large patches. Liriodendron tulipifera was important before and after logging. Large canopy dominants such as oaks and hickories were relatively unimportant sources of sprouts during early revegetation. Instead, minor canopy and understory species such as Robinia pseudoacacia, Halesia carolina, Acer rubrum, Cornus florida and Magnolia fraseri were the major sprouters in all patch sizes. The N-fixing black locust (Robinia) was much more important in large than small openings. -from Authors