Colorado State University Professor Leads National Drought Study on Grasslands

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A Colorado State University biologist will lead a national team that will experimentally impose severe drought in Great Plains grasslands and evaluate how the landscape responds – the first large-scale project of its kind.

The National Science Foundation has awarded $3.7 million to Alan Knapp, a biology professor and senior ecologist with the Graduate Degree Program in Ecology at Colorado State and principal investigator on the project. He will team with Melinda Smith at Yale University, who will soon join the Colorado State faculty; Scott Collins at the University of New Mexico; and Yiqi Luo at the University of Oklahoma. The project is an outcome of a research working group supported by Colorado State’s School of Global Environmental Sustainability.

In six grasslands – two each in Kansas and New Mexico and one each in Colorado and Wyoming – the scientific team will install slatted roofs over areas the size of small garden plots and take the same measurements to monitor ecological change. The roofs will remain for four years and allow only 40 percent of rainfall to reach the ground, simulating severe drought similar to that of the 1930’s Dust Bowl era.

“There are questions about how climate change is likely to impact ecosystems that are best addressed by looking at multiple ecosystems simultaneously,” Knapp said. “Typically, scientists have worked individually on these issues. We all conduct independent studies and we all measure different responses. Thus, we can never be sure if the ecosystems are behaving differently themselves because often our studies are difficult to compare. This large scale experiment is designed to overcome that problem.

“What is a common forecast for the future of all grasslands?” Knapp said. “Warmer temperatures are expected along with changes in rainfall patterns leading to more frequent and more severe weather extremes – including severe droughts that are more intense and last longer than they have in the past.”

Scientists will study plant and ecosystem productivity at each site, root growth, above-ground plant growth for cattle and overall change in community composition of plants during the simulated drought.

As Knapp and his colleagues point out in their NSF proposal, in the central United States, there are strong temperature and rainfall gradients from Texas to North Dakota and the dry plains of Colorado to eastern Kansas. The types of grasslands differ as well – from short grasslands in the west to tall grasslands in the east. These different grassland types are expected to respond differently to drought.

“In order to better forecast how entire regions will respond to expected climatic changes, there is a pressing need to understand why ecosystems differ in their sensitivity to changes in climate,” according to the proposal.

Knapp is a Fellow of the American Association for the Advancement of Science who has spent more than two decades researching ecosystem processes in grassland habitats. His renowned work in physiological plant ecology, or how plants respond physiologically to changes in the physical and biotic environment, won him Colorado State’s Scholarship Impact Award in 2009. The award is one of the highest annual honors given by CSU to faculty who have made national or international impacts with their studies.

Knapp will lead a team of postdoctoral fellows, graduate and undergraduate students that will assist with his piece of the project at the High Plains Grasslands Research Station near Cheyenne, Wyo., which is operated by the U.S. Department of Agriculture, and at Colorado State’s Shortgrass Steppe Research and Interpretation Center near Greeley.

The Shortgrass Steppe Research and Interpretation Center is adjacent to the Central Plains Experimental Range, which was established by the USDA in 1939 after the Dust Bowl to study sustainability of cattle grazing. The nearby Pawnee National Grassland provides additional research opportunities.