Factors determining the distribution of soil nematodes in a commercial forest landscape
Soil nematodes were censused at 99 forested sites in southern Mississippi, USA to examine the impact of forest management practices on the soil community. Taxonomic richness and numerical abundance in five feeding groups were linked to soil organic matter, phosphorus, shrub cover, and abundance of other nematode groups, consistent with limitation by availability of food items. Sites adjacent to streams showed significantly larger populations of plant feeders than nearby uplands. Sites plowed (bedded) for tree planting and sites recently excavated had significantly lower richness and abundance of plant feeders than undisturbed sites. Fungal feeder richness was depressed at excavated sites, which showed low concentrations of soil organic matter. Aboveground vegetation structure and landscape position appeared to have little influence on nematode distributions. Commercial plantations and sires with a history of frequent fire did not differ from undisturbed sites in soil properties or in any measure of the nematode community. No significant changes in soil properties or nematode fauna were observed over a 60-year chronosequence beginning at tree establishment. These findings suggest that aboveground disturbance affects the nematode community only to the extent that it influences the availability of potential hosts or prey in the soil. In contrast to aboveground events, disturbance of the soil had a clear impact on the nematode community, with a magnitude proportional to disturbance intensity. (C) 2001 Elsevier Science B.V. All rights reserved.