Role of nematodes in soil health and their use as indicators.

The composition of nematode communities (plant-parasitic and free-living) may be used as bioindicators of soil health or condition because composition correlates well with nitrogen cycling and decomposition, two critical ecological processes in soil. Maturity and trophic diversity indices withstand statistical rigor better than do abundances, proportions, or ratios of trophic groups. Maturity indices respond to a variety of land-management practices, based largely on inferred life history characteristics of families. Similarity indices may be more useful than diversity indices because they reflect taxon composition. Improving existing indices or developing alternative indices refined by a greater understanding of the biology of key taxa may enhance the utility of nematodes as bioindicators.