Vegetation patterns and transitions in drylands, such as shrub encroachment and grass invasions, are often sustained by positive feedbacks between ecosystem states and environmental conditions (e.g., sediment–vegetation interactions) or disturbances (e.g., fire, grazing), operating across scales from patches to landscapes. Drawing on a decade of research at shrub–grass ecotones in North American deserts, we identify internal feedback mechanisms—such as those involving soil moisture, microclimate, and nutrient dynamics—that reinforce shrub-dominated states, and demonstrate how these are altered by prescribed fire and grazing management. We hypothesize that similar feedbacks underlie transitions from native shrublands to invasive grasslands in other desert systems, such as the Sonoran Desert, although the ecological consequences may differ. Our findings suggest that both spatial heterogeneity, associated with shrub encroachment, and spatial homogenization, associated with grass invasions, can drive land degradation, depending on plant functional traits and feedback dynamics. These processes underscore the critical role of vegetation–sediment interactions in shaping pattern formation, state transitions, desertification, and the long-term stability of arid landscapes.

Sujith Ravi is a broadly trained environmental scientist interested in understanding the impacts of land use change and disturbances (natural and anthropogenic) on ecohydrological processes in terrestrial ecosystems. Dr. Ravi’s research addresses the challenge of managing scarce soil and water resources in the context of multiple demands and multiple constraints associated with land use change and disturbances, the core challenge facing the future of world’s food security and environmental quality. Dr. Ravi received his PhD (2008) in Environmental Sciences (Hydrology) from the University of Virginia. Prior to joining Temple University in 2014, he was a postdoctoral fellow at The Center on Food Security and the Environment at Stanford University. Dr. Ravi’s work has been recognized with a faculty early career award (NSF-CAREER) from the US National Science Foundation, the American Geophysical Union Editors Citation for Excellence in Refereeing, Distinguished Faculty Award for mentoring from Temple University, and Award for Excellence in Scholarship in the Sciences & Engineering from the University of Virginia. Dr. Ravi is currently serving as the Associate Editor of two major journals: Journal of Geophysical Research – Earth Surface (American Geophysical Union) and Ecosphere (Ecological Society of America).