FIG. 3.   Relationship between point (m ²-scale) species richness (mean number of species in individual pitfall traps) and site (hectare scale) species richness for sites along an environmental gradient in southeastern Arizona. Sites D and E do not conform to the strong correlation evident at other sites. Data are results from 15 pitfall traps at each site, pooled across two 48-h sampling periods (from Andersen 1997b ).