Friday, December 13, 2019

Long-running warming experiment turned off at RMBL

But the science continues

Courtesy RMBL

This July, the Rocky Mountain Biological Lab turned off the power to the longest-running warming experiment in the world. Dr. John Harte of the University of California–Berkeley established the experiment in 1990, creating five plots approximately 10 by 30 feet in size that were warmed approximately 4º F compared to five control plots interspersed with the warmed plots.

Research on the meadow has generated more than 35 scientific publications and supported at least 15 graduate students, tracking the impacts of warming on plants, insects and gas exchange, among other things.

According to Dr. Lara Kueppers of the University of California–Berkeley, who was not associated with the project, “The experiment was creative and visionary—seeking to mimic the whole ecosystem warming that occurs with more radiative heating from an atmosphere packed with extra CO2.”

Scientists used the plots to demonstrate that warmer temperatures cause a transition from showy wildflowers to sagebrush, which is more typical of habitats at lower elevations.

This transition is important because sage meadows store less carbon. There is a considerable amount of carbon stored in soil and the net effect of warming on carbon storage depends upon photosynthesis, in which plants take carbon out of the atmosphere to make plant material, carbon storage (in which carbon in the form of plants is put into soil) and plant decomposition (in which microbes release carbon to the atmosphere through breaking down plant material). The results suggest the possibility of positive feedbacks, whereby adding carbon to the atmosphere increases temperature, which in turn may add even more carbon to the atmosphere.

Dr. Stephanie Kivlin of the University of Tennessee led a team of scientists, including Dr. Aimee Classen of the University of Vermont, Dr. Jennifer Rudgers of the University of New Mexico and Dr. Lara Souza of the University of Oklahoma to decommission the experiment by collecting plant material and collecting soil samples from as deep as five feet. According to Dr. Kivlin, “We are very excited to be able to get deep soil samples from the world’s longest running warming experiment. These samples will yield insights for scientists around the world into the impacts of warming on carbon and the soil microbial community.”

According to RMBL executive director Dr. Ian Billick, “This is a great example of how the diversity and history of long-term research at RMBL create unique opportunities for scientists to understand ecosystems across the world.”

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