Symposium
Alexandra Wright
Assistant Professor
California State University, Los Angeles, California, United States
Current climate models predict an increased frequency and intensity of severe weather events over the next 20 years. In particular, rising global temperatures are expected to increase the severity and frequency of drought events worldwide. This aridification may increase the spatial extent of global drylands by up to 10% by 2100 due to decreased precipitation and increased evapotranspiration with climate warming. Importantly, altered weather patterns due to climate change may cause reduced rainfall in some areas but increase monsoon events and average rainfall in others. Thus, while the IPCC continues to report uncertainty in global average changes in meteorological drought (decreased precipitation), atmospheric aridity is increasing globally and driving reduced agricultural yields and ecological change. Thus, although drought research has focused more on how altered water inputs may affect dryland structure and function, changes in the fate and atmospheric demand for that water are already resulting in ecosystem shifts and transformation. < br>< br>Recent meta-analyses, syntheses, and experimental work have started demonstrating how atmospheric aridity (separate from decreased soil moisture) is a major driver of ecological change. In particular, atmospheric drying (measured using vapor pressure deficit) has increased by 0.25 kPa across the United States in the last 35 years. This corresponds with nearly 1C of summer warming and almost 2.5% lower relative humidity. Plants and ecosystems respond to these changes in VPD directly and dramatically. Increased atmospheric aridity can cause reduced stomatal conductance, increased rates of transpiration, rapid losses of soil water (and faster water cycling), reduced terrestrial gross primary productivity (even when soil moisture is held constant), altered nitrogen cycling, altered plant physiology, and morphology, and changes in plant community composition. To predict the future consequences of drought associated with global warming, we must focus our efforts on direct examinations of atmospheric aridity via land-surface models, novel experimental manipulations, and careful assessments of plant physiology.< br>< br>In this session, we will bring together experts who study these questions at multiple scales: plant physiology, community ecology, land management, and biogeochemistry. The talks will focus on the role of atmospheric aridity in driving ecological functioning across these scales to highlight a path forward for synthesis and experimental work. In order to predict the realistic consequences of climate change, what tools and knowledge will we need to modify our predictions about atmospheric aridity, associated soil drying, and ecophysiological response of plants, biological soil crusts, and soil heterotrophs?
Presenting Author: Alexandra Wright – California State University, Los Angeles
Co-author: Beatriz A. Aguirre, Ecology and Evolutionary Biology – Cornell University
Co-author: Stephanie L. Varghese – California State University, Los Angeles
Co-author: Sam Watson – NAU
Co-author: Austin Huynh – CSULA
Co-author: Daniel Guzman – CSULA
Presenting Author: Charlotte Grossiord – EPFL
Presenting Author: Sasha C. Reed, PhD – U.S. Geological Survey
Co-author: Cara Lauria – Southwest Biological Science Center, U.S. Geological Survey
Co-author: Armin Howell – U.S. Geological Survey
Co-author: Robin Reibold – U.S. Geological Survey
Co-author: Miguel L. Villarreal, Ph.D – U.S. Geological Survey, Moffett Field, CA, United States
Co-author: Bill Smith – University of Arizona
Co-author: Natasha MacBean – Western University
Co-author: Colin L. Tucker, PhD – USDA Forest Service-Northern Research Station
Co-author: Theresa McHugh – Institute for Health Metrics and Evaluation
Presenting Author: Zheng Fu – Laboratoire des Sciences du Climat et de l’Environnement