Diversity of nematode faunae under three vegetation types on a pallic soil in Otago, New Zealand

The mean numbers of nematodes in the upper 20 cm of soil in pasture, scrub, and podocarp forest were estimated to be, respectively, 4.2, 2.1, and 1.0 million/m(2); including a total of 44 taxa. Plant-feeding taxa dominated in the pasture soil. Soil from beneath scrub had the greatest proportion of fungal-feeders; the Shannon-Weaver index (H') was greatest at this site and, as many Dorylaimida were present, the value of the summed nematode maturity index (CMI) was also greatest here. Soil pH was lowest and C:N ratio highest under scrub. Bacterial-feeding nematodes were the most abundant group in the forest soil. In addition to uncertainty in allocating nematodes to feeding groups, absence of information on nematodes in other forest types and on the incidence of mycorrhizae makes it difficult to reach firm conclusions about contributions by nematode functional groups, trends in diversity, and an integrated ''soil quality'' index.