2024 McGinnies Scholar Presentation
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Wen Zhang, a Ph.D. candidate in the School of Natural Resources and the Environment, was named the 48th recipient of the William G. McGinnies Graduate Scholarship in Arid Lands Studies. The scholarship honors Dr. W. G. McGinnies, founder of the Office of Arid Lands Studies by recognizing and supporting students whose dissertation research investigates the physical and biological processes of the world’s arid and semiarid regions.
Abstract:
Dryland ecosystems are experiencing rapid changes driven by CO₂ fertilization, warming, hydroclimatic intensification, and increasing human pressures. Using more than four decades of satellite-derived vegetation indices as proxies for ecosystem productivity, we confirm a persistent greening trend across global drylands. However, this greening presents a paradox, as it masks a concurrent loss of ecosystem resilience. Enhanced early-season greening, driven by CO₂ and warming, can increase water demand and deplete soil moisture, limiting vegetation growth later in the season and leading to strong intra-seasonal stabilization effects. At the same time, ecosystem variability is increasing, indicating growing instability, characterized by rising upper bounds of vegetation activity alongside declining lower bounds. Under increasingly hotter and drier conditions, ecosystem resilience—defined as the ability to recover to pre-drought states—is declining, particularly under compound hot droughts, where recovery becomes slower and less complete. Together, these findings reveal that apparent greening in drylands conceals increasing instability and declining resilience under climate change.
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