A comparison of butterfly communities in native and agricultural riparian habitats in the Great Basin, USA

Native riparian habitats cover a small percentage of the landscape in most arid lands. Irrigation, however, artificially expands these in some regions . It is important to understand whether human-modified landscapes can suppo rt species native to natural ecosystems. We examined butterfly communities in relatively undisturbed (nonagricultural) versus artificially created (ag ricultural) riparian habitats in the Walker River Basin in the western Grea t Basin (Nevada and California, USA). Habitat type did not significantly af fect species richness. Butterfly abundance was greater, and evenness lower, in agricultural than in nonagricultural sites. Annual variability signific antly affected species richness, total abundance, and evenness. The few spe cies largely restricted to agricultural sites were geographically widesprea d and characteristic of disturbed habitats. Several relatively uncommon spe cies were not present in agricultural sites. Riparian habitats created to s upport agriculture may help support some native butterfly species, but cann ot substitute for undisturbed riparian habitats. (C) 1999 Elsevier Science Ltd. All rights reserved.