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Science of plant decomposition…and why it matters

U ecosystems ecologist Jennifer Follstad Shah explains her new research illustrating how human impacts affect decomposition of plant material in streams and what's at stake for the environment.

How plant material breaks down may not sound particularly interesting, but this process has important implications for the climate and the health of the environment.

PHOTO CREDIT: Jennifer Follstad Shah

To collect field data, researchers placed canvas strips in streams, as shown here in Red Butte Creek. Above photo: Jennifer Follstad Shah measures leaf decomposition rates in Red Butte Canyon.

Each year, Earth’s plants drop about 100 billion tons organic material, depositing vast amounts of leaves, sticks, bark and pollen into the environment. Much of it ends up in waterways where it decomposes, perpetuating a cycle that shuttles carbon back and forth between the environment and living things.

But human activities appear to be disrupting that vital process, according to new research by Jennifer Follstad Shah, an ecosystems ecologist and associate professor in the University of Utah’s School of Environment, Society & Sustainability.

(The College of Social and Behavioral Science this month formed the school by merging its Department of Geography and Environmental Studies program.)

She teamed with several other U.S.-based ecologists to analyze data from more than 500 freshwater streams and riparian areas around the world, including Utah’s Provo and Logan rivers and Red Butte Creek. They discovered that decomposition rates are increasing the most where human activity is impacting landscapes. Streams cover only 3% of Earth’s landmass, yet these aquatic ecosystems play an outsized role in the global carbon cycle, according to Follstad Shah.

The ecologist spoke with @theU about her team’s findings, reported recently in the journal Science.


The study, titled “Human activities shape global patterns of decomposition rates in rivers,” appeared May 30 in Science. Follstad Shah’s co-authors include Krista Capps and John Paul Schmidt, University of Georgia; Scott Tiegs, Oakland University; David Costello, Kent State University; Chris Patrick, Virginia Institute of Marine Science; and Carri LeRoy, Evergreen State College. Funding for the research came from the Ecuadoran National Science Foundation and the U.S. National Science Foundation.