The Nutrient Network

Thirty miles east of Fort Collins, a grassland site offers 360-degree views of the western Great Plains, the Rocky Mountains, and typically, grazing pronghorn or cattle.

It’s also the location of an international experiment uncovering how human activities are changing grassland ecosystems. For the last 10 years, researchers at Colorado State University and the U.S. Department of Agriculture-Agricultural Research Service have maintained about 40 square-meter plots of grasses that are easy to miss if you’re not looking for them. The plots are part of the Nutrient Network, a coordinated research effort across five continents systematically quantifying the effects of pollution and altered grazing patterns on grassland ecosystems around the world.

The plots are situated in the USDA-Agricultural Research Service’s Central Plains Experimental Range, one of the agency’s Long-Term Agroecosystem Research (LTAR) network sites.

Cynthia Brown, a professor in the CSU Department of Bioagricultural Sciences and Pest Management, has participated in the Nutrient Network since 2009 and has contributed to several studies.

Each spring and summer, Brown and colleagues, including Dana Blumenthal at the USDA-Agricultural Research Service and Julia Klein in the Warner College of Natural Resources, make detailed measurements of the grass species growing inside their experimental plots. They add nutrients such as potassium or nitrogen to certain plots and compare species diversity and plant growth from plot to plot. They submit their observations to an international database that compares grassland ecosystems across the globe, looking for patterns and trends.

“We hope to answer these really foundational questions about how the things we as humans are doing are affecting the systems we rely on,” Brown said.

Nature Ecology and Evolution report

Most recently, Nutrient Network scientists measured whether leaf traits, like thickness and seed production, respond consistently to experimental treatments in different environments. They discovered that some commonly characterized traits are actually poor indicators of plants’ responses to ecosystem disturbance. The results, published earlier this year in Nature Ecology and Evolution, were based on data gathered by researchers, including Brown, across 27 grasslands on four continents.

Researcher Cynthia Brown and grassland plot

Cynthia Brown, professor in the Department of Bioagricultural Sciences and Pest Management, points out different species thriving in one of her Nutrient Network plots.