Butterfly Assemblages Associated with Restored Riparian Uplands: Las Vegas Wash, Nevada, USA

ABSTRACT. The butterfly assemblage found at riparian upland plant restoration areas (after removal of the invasive plant, tamarisk (Tamarix ramosissima Ledebour)) along Las Vegas Wash was examined over four different months. Upland areas were planted with a variety of plants, however, those with a mesquite (Prosopis spp. Linneaus) component contained additional butterfly species relative to other plots. Detrended correspondence analysis demonstrated a gradient of butterfly species that corresponded with mesquite, age of stand, and homogenous areas of tamarisk. Some potential butterfly species went undetected; perhaps because required herbaceous understory plants were absent, or the need for greater densities of the hemiparasitic mistletoe (Phoradendron) (Nutt.) which is utilized by certain butterfly species. A single plot of exotic tamarisk, the near-past dominant shrub of the Wash landscape, was examined. An incursion of the beetle Diorhabda carinulata (Desbrochers), a phytophagous tamarisk control agent, appeared to affect tamarisk nectar production along with butterfly abundance at the plot. Butterfly response to nectar at inadvertent seep areas suggests these features are important for butterfly directed landscape restoration activities. Use of a characteristic butterfly community for identifying goals for upland restoration was valuable in describing end-points that incorporated assets of natural mesquite bosques.