SCALING OF THE TENEBRIONID BEETLE COMMUNITY AND ITS ENVIRONMENT ON THE COLORADO SHORTGRASS STEPPE

Ecological patterns and processes often change with scale, and determining how they do so is a necessary first step in understanding these relationships. We documented how the spatial patterns of beetle species richness, environmental variables, and correlations between the two change with spatial scale. Tenebrionid beetles and vegetation coverage were sampled on the shortgrass steppe of northeastern Colorado during June and August 1998. We used triplet quadrat variance (tQV) and triplet quadrat covariance (tQC) to evaluate the spatial patterns of beetle distribution and environmental variables. As revealed by tQV, spatial patterns of beetle species richness and environmental measures were scale dependent but differed among transects. Bare ground exhibited significant patchiness at spatial scales in the 460–500-m range, grass at 460–540 m, and shrubs at 420–620 m. Tenebrionid species richness in June showed significant patchiness in the 400–420-m and 560–640-m range, while August patch dimensions were in the 200–360-m and 400–520-m ranges. As revealed by tQC, correlations between tenebrionid species richness and environmental measures were not scale dependent, nor was there much variation between transects. Univariate, multiscaled analyses revealed potentially significant scales; however, covariate, multiscaled analyses revealed no scale dependence of interaction. These analyses showed (1) that while spatial scale is important, it is often unpredictable and (2) that multiscaled analysis in realistic settings may not capture species' relevant heterogeneity.