Characterizations of community and trophic structures of soil nematodes in a coastal Japanese black pine forest

The species diversity and abundance of soil nematodes can be an indicator reflecting environmental changes in a given soil ecosystem. As a rather simple type of forest ecosystem, coastal pine forests make a good model system for characterizing nematode communities. The purpose of this study was to determine the heterogeneity and community structure of soil nematodes in a coastal Japanese black pine (Pinus thunbergii) forest. We examined nematodes from sandy soils in the forest over one year and divided them into trophic groups based on morphological traits. The abundance of nematodes (per g dry soil) in all plots ranged from 0.4 ± 0.2 (mean ± SD) in February to 8.3 ± 4.4 (mean ± SD) in July. There was a significant interaction in the abundance of nematodes between the plots and months. Among 7,295 nematodes detected, the 18 taxa retrieved were dominated by the genera Aphelenchoides (24.3%), Ditylenchus (19.0%), and Acrobeloides (18.6%). The trophic structures of nematodes were continuously dominated by bacterivorous and fungivorous ones. These findings suggest that nematode distribution was spatially heterogeneous, their abundance varied with time, and the rather limited taxa of these trophic groups likely play important roles in the coastal soil ecosystem.