Vegetation responses to climatic and geologic controls on water availability in southeastern Arizona

Abstract Vegetation distribution, composition and health in arid regions are largely dependent on water availability controlled by climate, local topography geology. Despite a general understanding of climatic geologic drivers plant communities, trends responses to distribution storage across areas under different controls poorly understood. Here we investigate the multi-decadal interactions between spatial heterogeneity temporal variation their impacts vegetation (via normalized difference index, NDVI) monsoon-driven region southeastern Arizona. We find that grasslands display low NDVI respond directly monsoonal rainfall. In uplands, west-facing slopes canyons share similar averages variability, suggesting they both use from surface-groundwater flow paths through fractured rocks. Along San Pedro River, streamflow, groundwater, deciduous riparian woodlands strongly responsive rainfall, but stratifies wet (perennial), intermediate, dry reaches, underlain affect table elevation. These interact with driving climate shallow alluvial aquifer zone, primary source gallery phreatophytes. A recent shift toward strengthened monsoon has led an increase for reaches Pedro, while benefit is more muted along wetter where forest shows signs having reached its maturity, diminished NDVI. results have implications future vulnerability dryland change, which may be either dampened or intensified such as