Species diversity and community stability: cause or effect? a study using moorland spiders and other invertebrates

SUMMARY 1) Pitfall trapping was used to sample invertebrate communities on Monk's Moor, County Durham. 2) The effects of habitat and altitude upon communities of invertebrates, in particular spiders, were analysed using indices of alpha and beta diversity. The diversity indices were then compared to investigate any relationship between the diversity and stability o f the communities. 3) Spider diversity was significantly higher in heather moorland than in pasture. This was thought to reflect greater spatial heterogeneity within the heather moorland. No relationship was found between spider diversity and altitude. 4) A significant relationship was established between the invertebrate community and both habitat and altitude. However, it was limitations of the statistical technique, rather than biological effects that caused the significant relationship. 5) The lack of a marked effect of altitude upon diversity prevented detailed analysis of the diversity - stability hypothesis.