Abstract
Hanging gardens are relatively small, isolated mesophytic communities surrounded by the xeric environment of canyon walls in the entrenched dendritic drainage pattern of the Colorado Plateau (Welsh 1989a, Malanson 1980, Welsh and Toft 1972). Various sandstone formations such as the NavaJo in Zion National Park serve as aquifers which produce permanent seeps or springs when underlain by impervious layers (Welsh and Toft 1972). These reliable sources of water and the associated processes of erosion and sedimentation, allow the formation of biotic communities that starkly contrast with the surrounding desert. Several endemic plant species have been found in Utah hanging garden surveys (Welsh 1989b, Loope 1977, Welsh and Toft 1972) and Dinosaur National Monument (T. Naumann, personal comm.). Virtually nothing is known about the invertebrate fauna. Our specific research objectives are to (1) survey the plant and invertebrate animal communities of hanging gardens in Zion National Park (ZION) and Glen Canyon National Recreation Area (GLCA), (2) map the geographic distribution of the endemics identified and determine levels of endemism within and among parks; (3) determine levels of similarity between each sampled hanging garden plant and insect community, and to (4) determine similarities among plant communities and among insect communities across gardens.