Clark, T. A.; Stark, L. R.; Brinda, J. C.; Spence, J. R.

This report presents a preliminary bryophyte flora (bryoflora) for Grand Staircase-Escalante National Monument (GSENM) in southern Utah. The inventory included over 1000 collections made across 40 localities (i.e. macrohabitat types) spanning two ecologically important gradients in bryophyte habitat: shade and moisture availability. At present, the growing checklist contains 117 taxa of liverworts and mosses including 27 families, 65 genera, 116 species, 9 varieties, and 1 subspecies. Noteworthy records include 49 putative taxa new for the state of Utah, and 2 undescribed species in the genera Grimmia and Schistidium. We propose 4 of these species be considered for addition to the recently revised bryoflora of North America. As expected for arid and semiarid environments, the bryophytes of GSENM are predominantly acrocarpous mosses (75%) followed by pleurocarpous mosses (16%), thalloid liverworts (7%), and leafy liverworts (2%). The most diverse families included xeric-soil acrocarpous mosses in the Pottiaceae (35%) and xeric-rock acrocarpous mosses in the Grimmiaceae (15%). Both xeric and mesic species were recovered in the Bryaceae (10% of species) while the pleurocarpous Amblystegiaceae included mesic and hydric species (7%). Most species in the bryoflora have broad global or disjunct distributions, however notably, the known distribution of 17 species appears limited in the United States or globally, and warrant monitoring in GSENM. Using floristic habitat sampling across 19 macrohabitat types (combinations of 6 topography and 7 vegetation classes), mean site richness was 17.2 (9 SD) and ranged from 4 to 34 species. Six diversity hotspots supported greater than or equal to 30 species and were canyons with perennial or ephemeral streams dominated by mixed conifer, hardwood-riparian, riparian, or pinyon-juniper vegetation communities. High site-level species richness is likely supported by greater habitat diversity including xeric, mesic, and hydric conditions on variable substrates (e.g. rock, soil, biocrust, downed wood, seeps, and riparian aquatic/semi-aquatic habitats). Consequently, managing and monitoring diversity under future climate change and land-use alterations will necessitate a habitat-stratified approach that utilizes repeated floristic habitat sampling to document changes in site-level richness and to predict other candidate diversity hotspots on the basis of microhabitat-level diversity, which could be assessed by trained non-bryologists. Collection data are available to the public as georeferenced and photographed observations of half of the bryophyte collections on our iNaturalist.com project, Bryophytes of Grand Staircase Escalante, available for scientific, educational, or outreach activities. Observations are accessible to visitors who wish to know what species have been found along popular trails in GSENM. Landscape-level richness in GSENM may not reach that of the neighboring Grand Canyon National Park (over 155 species), which supports a unique high-elevation bryophyte community sheltered in the mixed conifer and spruce-fir forests of the North Rim's Kaibab Plateau. Future collecting by experts will inevitably uncover more species in this ecologically diverse monument important to conserving dryland bryophyte diversity and ecosystem function. This study serves as a baseline for future research and long-term monitoring related to climate change impacts on dryland bryophytes including biocrust species.