Spatial pattern in communities of crustose saxicolous lichens

Abstract

This paper describes two versions of a new method for detecting and examining spatial pattern in communities of crustose saxicolous lichens. One version is based only on the shapes of the lichen thalli and the second on the identity of their species. These methods are useful for examining the spatial structure of a lichen community for the presence of anisotropy, the phenomenon of having different scales of pattern in different directions. If present, the nature of the anisotropy has implications for our understanding of the processes that give rise to spatial pattern. Preliminary results from communities in the Canadian Rockies suggest that while individual species show some evidence of anisotropy, when all species are considered together, or when only the shapes of the thalli and their boundaries are considered, anisotropy is reduced or absent.