Nested spatial biodiversity patterns of nematode genera in a New Zealand forest and pasture soil

Biodiversity has a spatial dimension, which we estimated by examining generic turnover (beta diversity) of nematodes in adjacent forest and pasture sites. Dissimilarity was estimated in small and intermediate scale transects, the distribution of sampling points being determined by spatial simulated annealing. On an average, the forest yielded fewer nematodes per 24 mm dia 0–10 cm deep core than did pasture (435 vs 2818) but more genera (23.7 vs 19.1). Dissimilarity analysis suggests generic turnover is higher in forest than pasture, at both scales. At the small scale both communities have comparable dissimilarities up to 0.6 m, but only in forest does increasing distance increase dissimilarity. At the intermediate scale no spatial structure was apparent in the pasture nematode community, but in forest dissimilarity increased with distance, with no plateau. Quantifying the difference in spatial patterns between ecosystems illustrates the utility of geostatistical methods for addressing soil biodiversity.