Spider density and diversity in relation to disturbance in agroecosystems in New Zealand, with a comparison to England

Spider assemblages were sampled by quantitative sampling in pasture and arable habitats under different management regimes in the lower North Island of New Zealand. Density and species diversity increased with decreasing frequency and/or intensity of disturbance from two species and 1.8 individuals per m in wheat to 16 species and 130 indiv. per m in an abandoned, ungrazed pasture. The spider fauna was dominated by introduced species of money spiders (Linyphiidae). The most abundant species, Lepthyphantes tenuis, is also the most abundant one in British cultivated habitats. Additional pitfall trap samples from the same location and the Waikato, central North Island, indicated a similar species range containing mainly European species. A sample from a native tussock habitat had a completely different fauna, with only one species shared with the most undisturbed cultivated area. Comparative samples showed that similarly structured, but about twice as species- rich assemblages live in similar cultivated habitats in England.