Distribution of hanging garden vegetation associations on the Colorado Plateau, USA

Abstract

Hanging gardens are island-like habitats dominated by mesophytic-hydrophytic plant communities, growing on seeps on the xeric canyon walls of the Colorado Plateau in the American West. We measured the abundance of species and physical microhabitat characteristics of 73 individual hanging gardens during the growing seasons of 1991-1993. Cluster analysis of a simplified Morisita community similarity index matrix produced four distinct clusters of herbaceous vegetation: Adiantum capillus-veneris, Aquilegia micrantha, Calamagrostis scopulorum, and Cirsium rydbergii Herbaceous Associations. These associations are based on species abundance and are floristically described via summary tables showing dominance, constancy, and presence of hanging-garden endemic species. Univariate comparisons of species richness, hanging garden size, and dominance show that the A. capillus-veneris and A. micrantha associations tend to be smaller, less species rich, and have higher dominance values than the C. scopulorum and C. rydbergii asssociations. Two associations were dominated by species endemic to hanging gardens: Aquilegia micrantha and Cirsium rydbergii. These four hanging garden associations contrast with previous local vegetation surveys which place all hanging garden communities into one vegetation type despite the lack of a common dominant or constant species.

Citation

Fowler, James F.; Stanton, N. L.; Hartman, Ronald L. 2007. Distribution of hanging garden vegetation associations on the Colorado Plateau, USA. Journal of the Botanical Research Institute of Texas. 1(1): 585-607.