Seasonal dynamics of nematode and microbial biomass in soils of riparian-zone forests of the Southern Appalachians

In a study of the dynamics of labile forest-floor C and N in riparian zones of the Coweeta hardwood forest floor, we measured microbial biomass and nematodes (principally microbivores) in the top 10 cm seven times in a 10 month period. Total microbial biomass C ranged from 680 to 1270 μg g soil−1, and was significantly higher in the Fall, under Rhododendron than in the general forest area (tulip poplar and chestnut oak, co-dominants). Total microbial biomass N ranged from 80 to 220 μg g soil−1, reaching a peak in later summer. Nematodes averaged 11.3 × 106 m−2, among the highest known for nematodes in terrestrial ecosystems. With nematode microbivores averaging 5% of microbial biomass C, their effects upon the turnover of this labile microbial pool are considerable.