A framework for soil food web diagnostics: extension of the nematode faunal analysis concept

Nematodes, the earth's most abundant metazoa, are ubiquitous in the soil en vironment. They are sufficiently large to be identifiable by light microsco py and sufficiently small to inhabit water films surrounding soil particles . They aggregate around and in food sources. They include component taxa of the soil food web at several trophic levels. They can be categorized into functional guilds whose members respond similarly to food web enrichment an d to environmental perturbation and recovery. Indices derived through nemat ode faunal analysis provide bioindicators for disturbance of the soil envir onment and condition of the soil food web. We enhance the resolution of fau nal analyses by providing a weighting system for the indicator importance o f the presence and abundance of each functional guild in relation to enrich ment and structure of the food web. Graphical representations of food web s tructure, based on nematode faunal analyses, allow diagnostic interpretatio n of its condition. Simple ratios of the weighted abundance of representati ves of specific functional guilds provide useful indicators of food web str ucture, enrichment, and decomposition channels. (C) 2001 Elsevier Science B .V. All rights reserved.