OSU, Utah to estimate U.S. plant transpiration

Transpiration, the evaporation of water from plant leaves, accounts for more than half of all the global transfer of water from the continents to the atmosphere, but little is known about how much water is transpired across the United States.

With a $1.8 million from the National Science Foundation, scientists at Oregon State University and the University of Utah are teaming up to make initial estimates of U.S. plant transpiration. These data will be used to develop models and improve predictions of future plant water use, said Stephen Good, assistant professor in OSU’s College of Agricultural Sciences and principal investigator on OSU’s $933,377 grant.

“Water is a critical resource that sustains continental ecosystems, and land plants play a critical role in the cycling of water between the continents and atmosphere by extracting water from soils and groundwater and releasing it to the atmosphere as they grow,” Good said. “Surprisingly little is known about how much water is transpired, how different plants and ecosystems govern transpiration, and how ecosystems are shaped by transpiration.”

NSF announced the project today as part of its 2018 group of grants made under the agency’s MacroSystems Biology and Early National Ecological Observatory Network Science programs. The grants, which shed light on diverse and highly relevant environmental issues, support research that helps understand biosphere processes and their complex interactions with climate, land use and invasive species, from regional to continental scales.

Eighty-one sites around the United States constitute the National Ecological Observatory Network (NEON). The network provides a unique combination of air-, ground- and water-based sensors and field sampling with statistical, physical and biological modeling.

The interdisciplinary research team will work with a wide range of NEON-produced data products, with an emphasis on stable isotope ratios of water vapor and carbon dioxide. Isotope ratios provide an integrated measure of physical processes controlling gas exchange between plant leaves and the atmosphere. The suite of NEON sensors provides the first standardized data set enabling isotope-based estimation of transpiration across a diverse range of continental ecosystems.

OSU researchers are Good, David Noone, professor in the College of Earth, Ocean, and Atmospheric Sciences; and Christopher Still, associate professor in the College of Forestry. The University of Utah team includes Gabriel Bowen and William Anderegg.