CLASSIFYING SIGNIFICANTLY DIFFERENT TYPES OF SPRINGS ECOSYSTEMS WITH PHYSICAL, BIOLOGICAL, AND ANTHROPOGENIC-IMPACT INVENTORY DATA IN THE GRAND CANYON ECOREGION

Due to the recent abundance of high-quality, springs-ecosystem, interdisciplinary-inventory data, it is now possible to classify types of springs with their physical, biological and anthropogenic-impact factors. A floristic assemblage analysis of 352 Grand Canyon Ecoregion (GCE) springs among four common spring types: helocrene wet meadows, hanging gardens, rheocrene channel springs, and hillslope springs found the highest known plant species packing of any analyzed floristic region. High levels of biodiversity at springs are attributed to the co-occurrence of multiple geomorphic microhabitats created by the emergence environment and steep ecological gradients in moisture, productivity, and nutrient availability. Microhabitat richness is positively related to floral species richness; however, geochemistry, geomorphic microhabitat richness, and anthropogenic impacts also exert important controls on vegetation among springs types. The four springs types were distinguished by differences in physical site characters, and were associated with discrete plant assemblage composition and structure. Plant species packing was almost 1,000 species, more than 45% of the entire regional flora recorded in 45 ha (< 0.1% of the total GCE land area). Geomorphic microhabitat abundance and diversity were positively related to springs plant diversity. Key physical, biological, and anthropogenic impact differences among springs types were observed, and demonstrates that springs are highly diverse and individualistic ecosystems, each existing in a unique ecohydrological context with a discrete biogeographic history. Unique indicator plant species where identified for each springs type. Stewardship considerations should include protection of rare springs types (such as gushet), wetted area, and species. The critically imperiled global status of springs demonstrates the need for improved mapping, inventory, ecological assessment, restoration, and monitoring.