EFFECTS OF SHELTERWOOD TIMBER HARVESTING ON UNDERSTORY VEGETATION, SOIL NUTRIENTS, AND ENVIRONMENTAL FACTORS IN A VIRGINIA PIEDMONT FOREST 3-5 YEARS POST-HARVEST

Shelterwood timber management methods impose moderate ground disturbance and allow increased light penetration to the understory after partial canopy removal. This study is a two-year segment of a long-term project analyzing understory vegetation patterns over time on shelterwood sites harvested in 1997 (n=4) and 1998 (n=2), and on mature, secondary-growth control sites (n=2). The sites were predominantly oak-hickory stands located in Appomattox and Buckingham counties, Virginia. Data were collected May - June of 2001 and 2002.Ten fixed plots were established on each of eight study sites and all plant species within the plots were identified. Coverage estimates were made for individual species and for the total amount of understory vegetation present in each plot. Canopy coverage was measured at each plot using a spherical densiometer. Soil samples collected were analyzed for pH, organic matter, and nine nutrients. Temperature, relative humidity, and light levels were measured under full canopy in August 2002. A total of 139 species were found across the sites. The shelterwood sites grouped by harvest year were found to be significantly higher in total vegetation coverage, diversity, and richness, and significantly lower in canopy coverage than the · controls, but not from each other. Changes in understory vegetation from 2001 to 2002 were minimal. Some species occurred strongly across all sites, including the control sites, regardless of time since harvest (e.g. Acer rubrutn, Nyssa sylvatica, Quercus spp.). Other species were dominant on shelterwood sites, but not the controls sites (e.g. Liriodendron tulipifera, Andropogon virginicus). Species appearing after harvest were mostly early­ successional forbs and grasses. A few species were found only on the control sites, or were more highly ranked there (e.g. Chimaphila maculata and Sassafras albidum). Canopy coverage had a significant negative relationship with species richness, diversity, and total vegetation, forb, tulip poplar, and blackberry coverage.Total vegetation coverage had a significant positive relationship with the same variables. All sites were acidic, but pH decreased with harvest year. Organic matter was high across sites. Calcium was the only macronutrient showing significant change (decrease) across harvest year treatments. Environmental variable analysis was largely inconclusive, but light did show significant increases on shelterwood sites compared to controls. While harvesting did impact several important variables, indications are that shelterwood sites of this age are not undergoing rapid changes in their vegetation patterns.