Vegetation of Grassy Remnants in the Las Vegas Valley, Southern Nevada

Abstract

The approximately 1000-km² Las Vegas Valley contains a rich assemblage of unique plant communities in the eastern Mojave Desert. Yet, there is little published documentation of this vegetation as its destruction continues with proceeding urban development. Development has intensified after the 1998 Southern Nevada Public Land Management Act mandated the disposal of federal lands. We document plant communities at four unique grassy remnants, some of which have since been destroyed, in the southwestern Las Vegas Valley. Sample plots of 0.25 or 0.09 ha at each site contained washes (supporting catclaw [Acacia greggii] at three sites) and associated uplands. Native perennial grasses comprised 12% of plant species richness/100 m2 and 5% of total relative cover on average. A total of 8 native perennial grasses were detected at the four sites, with predominant species including fluff grass (Dasyochloa pulchella), purple three-awn (Aristida purpurea), big galleta (Pleuraphis rigida), red grama (Bouteloua trifida), and slim tridens (Tridens muticus). These communities appeared as grass-shrublands, rather than the widespread shrublands commonly described for the Mojave Desert. Of large shrubs at the three sites containing catclaw, catclaw density ranged from 52-124/ha, Mojave yucca (Yucca schidigera) from 8-32/ha, and creosote bush (Larrea tridentata) from 168-456/ha. We also obtained permission to salvage native plants from one site prior to land development. Overall survival of salvaged plants of eight species exceeded 76% after one year of greenhouse/outdoor storage. We suggest that while many opportunities have already been lost, collecting and documenting information on the rich vegetation of the Las Vegas Valley and salvaging native plants or seed for use in desert landscaping, parks and habitat improvement in protected areas would leave a future legacy of this ecologically unique region.