Drought-induced variability in the sagebrush ecosystem: a broader view captures lag effects and recovery

Keywords: drought, MODIS, Google Earth Engine, ecosystem productivity
Abstract Type: Paper Abstract

Abstract

Mortality of sagebrush (Artemisia spp.), perennial grasses, and other shrubs was documented in Upper Green River Basin several years after a major drought (2012). The lagged observations underscore the need for an improved understanding of vegetation response. A consideration of the variability in patterns of plant productivity with respect to climate is essential to exploit landscape scale remote sensing for detection of subtle changes associated with mortality in this sparsely vegetated ecosystem. We calculated monthly productivity anomalies from a 23-year period (2000-2022 of Moderate Resolution Imaging Spectroradiometer satellite imagery) to identify the spatial and temporal variability associated with drought and recovery cycles. Growing season anomalies highlighted dramatic declines in productivity during the 2012 and 2013 growing seasons. However, large negative anomalies persisted in other areas during the 2014 growing season, before beginning to rebound in subsequent years. The cumulative precipitation deficit autumn, winter, and spring and summer temperature from the preceding year were consistently the most important climate variables in explaining negative growing season anomalies. Our analysis identified spatially explicit patterns of ecosystem properties altered by severe drought, which are consistent with field observations of mortality, and highlights the lag effects of drought. Local areas that exhibited a strong negative deviation from the long-term trend between 2012-2014 rebounded strongly in 2015-2016. The results suggest that heat stress played an important role in the drought and future models should incorporate both heat and moisture stress in drought predictions in the sagebrush ecosystem.