Responses of soil microbial biomass, nematode trophic groups, N-mineralization, and litter decomposition to disturbance events in the southern Appalachians

Abstract

Seasonal measurements of soil microbial biomass, nematode trophic groups, net N-mineralization, net nitrification, net ammonification, litter decomposition, and soil respiration rates were examined to assess the effects of rhododendron ( Rhododendron maximum L.) removal and hurricane windthrow upon these factors. Comparisons of pre- and post-disturbance quantities of soil microbial biomass carbon ranged from 503 to 1080 μg C g soil −1 and microbial biomass nitrogen ranged from 67 to 169 μg total persulfate nitrogen g soil −1, showing no significant differences or trends in response to these disturbance events. Total nematode abundance ranged from 13.05 to 54.31 nematodes g soil −1 and showed no significant differences in response to these disturbance events, although overall nematode abundance was declining in the disturbed plots at the end of the study. Nematode trophic structure was fairly consistent across both sites and all sampling dates and exhibited no discernible trends in response to these disturbance events. Rates of net N-mineralization, nitrification, and ammonification exhibited greater variability, post-disturbance. Litter decomposition rates and soil respiration rates decreased following the disturbance events, with respiration rates in the Cut plot being significantly higher across years. Overall, the effects of these disturbance events upon soil properties were highly variable and were unrelated to the major increases in N loss that were detected from deeper soil horizons following the hurricane windthrow event.