Nematode communities as indicators of status and processes of a soil ecosystem influenced by agricultural management practices

Nematode communities were monitored for three years in a citrus soil ecosystem in Central Florida under various agricultural regimes comparing standard vs, reduced-input practices. Differences in agricultural regimes consisted of two fertilization levels, two irrigation levels, and two types of ground cover under the tree (herbicide vs. mulch). While some nematodes were affected sporadically by fertilization and irrigation treatments, mulch had a consistent and frequently significant effect on many bacterivores, fungivores, herbivores, and omnivores. Rhabitidae, Cephalobus, Aphelenchus, and Aphelenchoides had an immediate but temporary response to mulch additions. Acrobeles, Acrobeloides, Eucephalobus, Teratocephalus, Criconemoides, Aporcelaimellus, and Eudorylaimus were always less abundant in mulch-treated plots, whereas Plectus and Belonolaimus were always more abundant. Of various indices of community composition, only maturity indices, unlike diversity indices, indicated the status and intensity of soil processes (decomposition, mineralization). However, different responses of single genera within a trophic group implied unique contributions of nematode genera in soil ecosystem processes on a temporal scale, suggesting that generic or possibly species level of resolution provide the most adequate information about the soil ecosystem. (C) 1999 Elsevier Science B.V. All rights reserved.