We studied butterfly assemblages at six types of riparian landscapes in five different watersheds in the southwestern United States ( sites). Sites included exotic-invasive Tamarix ramosissima (tamarisk) dominated sites; sites where tamarisk was controlled, but not actively revegetated; sites revegetated with upland plants; sites where control was followed with riparian plant revegetation; native riparian vegetation sites; and sites that were a mixture of native and tamarisk vegetations. Local butterfly species were linked regionally by identifying species consisting of more sensitive butterflies that are less resilient to vegetation changes and environmental perturbations and then identifying a subgroup that was reported from all watersheds. This allowed for a regional assessment relevant to all watersheds. Significant differences were found between the abundance of these in-common disturbance sensitive species at different landscapes. Sites where tamarisk was removed without restoration had butterfly metrics similar to the low values at tamarisk sites. The assumption that tamarisk removal is sufficient to recover sensitive species was not true in cases we examined. Soil moisture and riparian condition were identified as important variables associated with abundance of more sensitive butterfly species. Results support the importance of reinstating stream-flow regimes and suggest active restoration of sites if sensitive riparian wildlife species are desired. 1. Introduction Exotic plants can impact ecosystems through changes in fire regimes and hydrological cycles, hybridization with native species [1], displacement of native plants [2], and reductions in energy availability for native food webs [3]. Riparian ecosystems may be especially vulnerable to negative changes caused by invasives because of the ability of water to spread alien plant materials [4]. Tamarisks (Tamarix: Tamaricaceae), native to southern Eurasia, are invasive in the western United States and have replaced native plant communities in 470,000 to 650,000？ha of primarily riparian floodplain habitat in the western USA [5]. Tamarisk eradication and control projects are regularly undertaken for a variety of reasons (e.g., [6]), often with the goal of improving wildlife habitat [7]. Recognized data gaps for effects of tamarisk on wildlife include comparisons of tamarisk-invaded habitats and tamarisk removal sites with native riparian vegetation sites [8]. Studies examining effects of tamarisk and tamarisk control on wildlife have generally focused on single watersheds [9] and data is
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