Natural resource condition assessments for six parks in the Mojave Desert Network

Fleishman, Erica; Albano, Christine; Bradley, Bethany; Creech, Tyler; Curtis, Caroline; Dickson, Brett; Epps, Clinton; Hegeman, Ericka; Hoglander, Cerissa; Leu, Matthias; Shaw, Nicole; Schwartz, Mark; VanCuren, Anthony; Zachmann, Luke

This Natural Resources Condition Assessment (NRCA) for six parks in the Mojave Desert Network—Death Valley National Park, Grand Canyon–Parashant National Monument, Joshua Tree National Park, Lake Mead National Recreation Area, Manzanar National Historic Site, and Mojave National Preserve—is intended to provide scientific information on park resources that was requested by park managers and will be applicable to their planning and decision-making. Region-level and park-unit level objectives for the NRCA, and associated priorities for assessment, largely were identified by managers from these six parks. For cases in which few data were available to directly assess the conditions of high-priority resources, park managers and our assessment team agreed that we would review relevant literature and outline data requirements and analytical methods that likely would allow such an assessment. Because the distributional ranges of several iconic species, and a high proportion of stressors to natural resources, occur over much of the Mojave Desert, park managers and our assessment team agreed that wherever possible, we would assess resources at the regional level. We agreed to supplement the regional assessment with evaluations of the condition of a small number of resources that were of interest to a particular park or subset of parks. High-priority natural resources across the Mojave Desert Network include elements of the three components of biological or ecological diversity: structure, composition, and function. National Park Service (NPS) personnel indicated that management of areas under their jurisdiction might best be informed by a focus on assessment of processes rather than individual species. On the basis of our scoping and discussions with Mojave Desert Network personnel, we agreed to emphasize the following resources and stressors: climate change, land use, air quality, fire, the distribution and dynamics of non-native plants, habitat quality for Mojave desert tortoise (Gopherus agassizii), connectivity and adaptive capacity of desert bighorn sheep (Ovis canadensis nelsoni), water availability for native wildlife, feral burros, bats, and mule deer (Odocoileus hemionus) in Grand Canyon–Parashant. The responses of different species, ecological processes, and non-climate stressors to ongoing and projected changes in climate by 2100 will not be uniform; some responses likely will be considered negative, whereas others may be considered positive. As summarized in a recent, publicly available technical assessment of climate change in the southwestern United States, the scientific community has high confidence that annual and seasonal average temperatures, the length of the frost-free season, and the number and intensity of heat waves have increased and will continue to increase. Additionally, the scientific community has high confidence that mountain snowpack will decrease. There is medium-high confidence that spring precipitation will decrease and that drought severity will increase. Land use and its effects of land cover both within and outside of parks affect natural resources within parks. Data on land use are highly relevant to analyses of the human footprint, which generally is defined as the effects on the environment or natural resources of human presence and actions. We examined both the physical effect area of the human footprint (the actual area covered by human-created features) and the ecological effect area (the area within which species or ecological processes are affected by human-created features). We found that publicly available data on human-created features often were inconsistent with data collected by park units or with data derived from high-resolution, remotely sensed images.

Natural resource condition assessments for six parks in the Mojave Desert Network

Series

Collections