Landscape pivot points and responses to water balance in national parks of the southwest U.S.

1. A recent drying trend that is expected to continue in the southwestern U.S. underscores the need for site-specific and near real-time understanding of vegetation vulnerability so that land management actions can be implemented at the right time and place. 2. We related the annual integrated normalized difference vegetation index (iNDVI), a proxy for vegetation production, to water balance across landscapes of the Colorado Plateau. We determined how changes in production per unit of water (vegetation responses), and the water balance amounts at which production shifted from above to below average values (pivot points), varied across dominant vegetation and soil types. 3. Precipitation (PRCP), actual evapotranspiration (AET), water deficit (D), and soil moisture (SM) explained 13 – 82% of variation in vegetation production. Along an increasing water availability gradient, vegetation responses to PRCP and AET increased, responses to SM decreased, and responses to D became more negativ...