Long-term disturbance effects in the nematode communities of south Mississippi woodlands

The effects of soil disturbance on the nematode community were assessed at 30 sites on the outer coastal plain of Mississippi, representing four ages since soil disturbance plus a control group of six undisturbed sites. Thirty-five taxa were encountered, dominated in abundance and taxonomic richness by plant and bacterial feeders. Nematodes were more abundant and more taxonomically rich in sites with a low slope and deep litter cover, distant from trees. Plant feeders were more numerous at sites with a dense herb cover, suggesting limitation by food availability. When sites were arranged as a chronosequence, herb cover, litter depth, soil organic matter, soil moisture, and tree canopy cover increased through time consistent with succession to forest. The abundance of most trophic groups decreased in the 10 to 20 years following disturbance and increased thereafter, a pattern repeated in taxonomic richness of plant and bacterial feeders. Fifty years after disturbance, nematode abundance had not returned to levels observed in control sites. These results suggest that nematode succession following soil disturbance is a gradual process regulated by establishment of aboveground vegetation. There was no evidence of dispersal limitation or facilitation by colonist nematode species.