How climate change could affect the impact of nematodes on grasslands

Soil food webs play a key role in supporting grassland ecosystems, which cover about a quarter of the land on Earth. Climate change poses a threat to these environments, partly due to the uncertainty of extreme rainfall, which is expected to increase.

To learn more about the effects of these extreme events, a team of soil and plant ecologists, led by the faculty of Colorado State University, studied nematodes, commonly known as nematodes, which play a key role in the carbon and carbon cycle. nutrients and decomposition in the soil.

By simulating low and high rainfall at grassland research sites in Colorado, Kansas and New Mexico for two years, the researchers found in extreme drought conditions that predatory nematodes decreased significantly, which led to the growth of nematodes that feed on of roots. Typically, these predatory nematodes feed on root-eating species.

Scientists said the findings could have serious implications for grassland productivity due to climate change because in drought conditions, having fewer predatory nematodes allows herbivore populations of roots to explode, which could reduce root production. grass.

CSU scientist André Franco and distinguished Diana Wall University professor led the study, in collaboration with Professor Osvaldo Sala of Arizona State University and Laureano Gherardi, an associate postdoctoral researcher.

The study was published on June 10 on Proceedings of the National Academy of Sciences.

research conducted at the Semiarid Grassland Research Center in Northern Colorado
Moving forward, the research team hopes to learn more about the interaction between water and nematode stresses for plants. Photo courtesy of Andre Franco / CSU

Researchers have already figured out that root-feeding nematodes are incredibly important for controlling the amount of soil carbon that an ecosystem can store from the atmosphere. In this new study, the scientists found that root-feeding nematodes thrived more in wetter regions that suffered from drought than in drier sites.

Franco said the research team is now analyzing the combined soil and plant results from these sites to learn more that plants will suffer more than previously thought due to extreme drought conditions. CSU scientists are also replicating the research in a controlled environment in a greenhouse, examining the interplay between changes in soil moisture and fauna composition.

“Root biomass responds to most of the carbon sequestered in grasslands, and it could be that the increasing root feeder population is exacerbating the negative effects of drought on carbon sequestration in these ecosystems,” he said.

The research team hopes to learn more about the interaction between water and nematode stresses for plants and whether these effects could be even worse for ecosystem functioning than they previously thought.

Other CSU co-authors include Cecilia Tomasel, Walter Andriuzzi (now editor at Nature Communications), Katharine Ankrom, Ashley Shaw (now postdoctoral researcher at the University of Oregon) and Elizabeth Bach (now scientist at The Nature Conservancy in Illinois).

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