OPUS: CRS Predicting establishment, competitive interactions, and mortality in desert shrub populations based on spatial structure and intrinsic water-use efficiencies

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Over the past four decades, changes in both temperature and precipitation within the Mojave Desert of the western United States have impacted shrubs living in this desert environment. Temperatures are increasingly warmer and the region is getting progressively drier. In this study, 39 years of drought-deciduous shrub population and physiological observations (some 265,000 data points) will be synthesized to advance our understanding of how the combination of drought and El Niño events along with differences in shrub physiologies have shaped plant population structure in western deserts. Such information is important for land managers, resource specialists, and ecologists as they seek to better manage extensive arid regions of the western United States and to understand how future changes in climate will impact these arid land ecosystems. The concepts synthesized in this study use data that has already been collected and will link spatial patterns of plant establishment and survival with environmental variables and intrinsic differences in the efficiency of water use by different desert shrub species. This research aims to understand how plant-plant and plant-environment interactions structure desert plant populations and how changes in climate affect these patterns. The focus of the synthesis is on observations leading to predictive constructs at three key life-history stages when population structure is affected: establishment, competition among adult individuals, and population decline under abrupt and extreme droughts. This synthesis will also generate predictions about how ecophysiological aspects of population structure will change if future climate trends follow the wet-dry pattern of the last 39 years or if the long term wet-dry cycles of the last century return. This synthesis will provide a framework for understanding how variation in plant physiology among desert plants operate at both the population and interspecific levels to affect structure of desert plant populations and how these patterns will be affected by the environmental variability already occurring.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.