The ground beetle and spider fauna of managed and unimproved upland pasture

Abstract

Ground beetles and spiders were sampled in 1985 and 1986 by pitfall trapping in improved upland grassland and unimproved grass and heather moorland. The aim of the work was to gain a preliminary idea of some effects of upland management on the dominant groups of epigeal polyphagous predatory arthropods. Unimproved sites had a much more diverse fauna and a larger catch of both groups, when compared with the improved grassland. There were, however considerable differences between the faunae of the individual unimproved sites. Improved grassland sites all had a rather similar, depleted fauna of both ground beetles and spiders. Improved sites which had been sprayed with the pesticide chlorpyrifos had a very low catch of ground beetles compared with unsprayed sites, but the catch was more diverse, consisting of small numbers of individuals of a wide range of immigrant species. There were no clear differences between the spider faunae caught on chlorpyrifos-sprayed and unsprayed sites. It is suggested that pasture improvement has a more drastic effect on ground beetle and spider communities than does subsequent pesticide use.