Population dynamics and functional roles of Enchytraeidae (Oligochaeta) in hardwood forest and agricultural ecosystems

Population dynamics of enchytraeids are described for 2 montane forested watersheds in southwestern North Carolina (Coweeta) and an agricultural site under conventional (CT) and no-tillage (NT) management in the northeastern Georgia piedmont (Horseshoe Bend, HSB). Given that much of the taxonomy, ecology and community structure of enchytraeids is poorly known, our objective was to identify key “indicators” of enchytraeid community structure which could be used, in this case, to better understand their role in soil structure formation. Although population densities of enchytraeids were higher in the forested (Coweeta) than in the arable soils (HSB), the average ash free dry weight per enchytraeid at HSB was nearly double that found at Coweeta. Based on these measurements and an estimate of their gut transit time, we calculated that the enchytraeids at HSB transported 2180 g of soil per m2 per year compared to 443 and 393 g m-2 yr-1 for watershed 18 and 27, respectively at Coweeta. We therefore hypothesize that enchytraeids have a larger influence on soil structure in agricultural fields than in forested areas, in spite of lower population densities. The ash free dry weight and ash wt. per enchytraeid may qualify as key “indicator” parameters of enchytraeid community structure which helps to understand their functional role in ecosystems, though more studies are called for.