Abstract
A novel approach of calculating the spatial autocorrelations of 20 independent environmental
factors was applied to project potential distributions of 8 rare orchid species (with fewer than 5
occurrences). The occurrences of these orchids were overlaid on environmental layers with significant spatial autocorrelations to identify possible areas of distribution and relevant environmental factors. Results showed that some species’ distributions located in regions with
high spatial autocorrelations, suggesting unique habitat requirements. In contrast, several
species’ occurrences scattered over areas with low spatial autocorrelations, and their rarity was possibly due to anthropogenic disturbance, fragmentation, or geological history. The spatial
analysis developed here indeed provided applicable information for rare species distributions
which is difficult to project using typical species distribution models. The results also showed
that spatially autocorrelated habitat conditions seemed to be positively related to endemicity
but negatively related to species richness.