PARENT SESSION
Poster Session 30: Soil Ecology.

Wednesday, August 4 Presentations from 5:00 PM to 6:30 PM, Exhibit Hall A 1.

Silvopastoral thinning effects on rates of surface decomposition of leaf litter.

Halvorson, Jonathan ^*,1, ¹ USDA-ARS Appalachian Farming Systems Research Center, Beaver, WV, USA

ABSTRACT- Silvopastoral management strategies in hill-land Appalachia seek to expand spatial and temporal boundaries of forage production and promote ecosystem integrity through a combination of tree thinning and understory pastures but subsequent changes to the microclimate may affect rates of decomposition, nutrient cycling and retention of soil organic matter. We used litterbags and minicontainers to measure the effects of tree thinning and time of year on decomposition rates of leaf litter from common Appalachian tree species; yellow poplar, Liriodendron tulipifera, red maple, Acer rubrum, white oak, Quercus alba, and eastern white pine, Pinus strobes. In general, we observed faster decomposition rates for samples in minicontainers compared to traditional litterbags, likely due to sample grinding needed for minicontainers. However, for either method, yellow poplar litter lost more mass after one year, (55-68%) than maple (38-56%), oak (26-43%) or white pine (16-36%). Silvopastoral thinning treatments had little effect on decomposition rates of yellow poplar or maple litter but rates for white oak and white pine litter were least in open sites, intermediate in thinned sites and greatest under unthinned canopies. After one year in the field, mass loss for samples first exposed in the fall were similar to samples initially exposed in the spring. These results suggest average decomposition rates in silvopastoral systems may be faster than in open pasture and slower than under an unthinned forest canopy but do not account for disturbance effects on soil organic C, typically high in forest soil organic horizons.

Key words: litterbags, decomposition, silvopastoral