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 an d arable habitats under different management regimes in the lower Nort h Island of New Zealand. Density and species diversity increased with decreasing frequency and/or intensity of disturbance from two species and 1.8 individuals m(-2) in wheat to 16 species and 130 indiv. m(-2) in an abandoned, ungrazed pasture. The spider fauna was dominated by i ntroduced species of money spiders (Linyphiidae). The most abundant sp ecies, Lepthyphantes tenuis, is also the most abundant one in British cultivated habitats. Additional pitfall trap samples from the same loc ation and the Waikato, central North Island, indicated a similar speci es range containing mainly European species. A sample from a native tu ssock 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 asse mblages live in similar cultivated habitats in England.