MICROBIAL SPATIAL HETEROGENEITY IN MICROBIOTIC CRUSTS IN COLORADO NATIONAL MONUMENT .1. ALGAE

Spatial heterogeneity in visually similar sites under Utah juniper can opy in Colorado National Monument was examined. Sample sites were arra nged in a transect 24 m long, such that distances between samples were 0.013 m, 0.03 m, 1.0 m, 12 m, and 24 m. Twenty-five taxa of algae wer e observed, mostly belonging to Cyanophyta. Algal density varied by mo re than order of magnitude within the 46 samples examined. The coeffic ients of variation for each distance class were very similar, demonstr ating that algal patchiness can be as significant on a scale less than 0.013 m as it is on a scale of 24 m. Goodall's random pairing analysi s of spatial pattern supported this conclusion by indicating that the minimal area for sampling soil algal crust populations at this site wa s equal to or less than 0.013 m. Because of the microscale heterogenei ty in algal communities in this study, we recommend that future resear chers take composite samples if they wish to quantify algae of microbi otic crusts.