Grasslands More Sensitive to Dryness than Rainfall, Study Says

by |March 9, 2017
Oglala National Grassland, Nebraska. Photo: Brian Kell

Oglala National Grassland, Nebraska. Photo: Brian Kell

A new study shows that dryness of the atmosphere affects U.S. grassland productivity more than rainfall does. The findings could have important implications for predicting how plants will respond to warming climate conditions.

Scientists at Stanford University and Columbia University looked at 33 years of climate and vegetation satellite data to determine how plants regulate water and carbon dioxide under dry conditions. The team concluded in a study published online March 6 in the journal Nature Geoscience that U.S. grasslands are more than three times more sensitive to vapor pressure deficit, or atmospheric dryness, than they are to precipitation. The study’s large-scale methods to understand plant behavior could be used to improve predictive models of how environments will respond to rising temperatures and droughts, which are expected to intensify in the 21st century.

“Just looking at changes in precipitation isn’t going to tell you the whole story,” said lead author Alexandra Konings, formerly a postdoctoral fellow in Columbia Engineering Professor Pierre Gentine’s lab and now an assistant professor of earth system science in Stanford’s School of Earth, Energy & Environmental Sciences. “U.S. grasslands are way more sensitive to vapor pressure deficit, which is important. Because [vapor pressure deficit] is so tightly linked to temperature, we can predict that it’s going to keep going up in the future.”

Gentine is also an associate professor with the Earth Institute and works with the Columbia Water Center. He will lead related field research in Oklahoma this spring that could also help fine tune hydrologic and climate models. The project will look at how temperature, air turbulence and moisture interact along the land surface to produce evaporation and drought. They will use fiber-optic cables and lasers to make fine-scale measurements—a sample every second, every 10 centimeters—along a mile-long cable stretched across agricultural land.

From Columbia Engineering. Read the full story about the new study in Nature Geoscience here.

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