U.S. Department of Energy Office of Biological and Environmental Research

PI-Submitted Research Highlights for
Terrestrial Ecosystem Science Program

Temperature Response of Soil Respiration Largely Unaltered with Experimental Warming

Scott D. Bridgham
Institute of Ecology and Evolution, University of Oregon

Highlight

November 16, 2016
Global temperature response of soil respiration consistent across biomes.

The Science
A synthesis of 27 experimental warming studies across nine biomes showed the soil respiration increased with temperature to about 25 °C, with rates decreasing with further warming. No acclimation of soil microbes to warming was found.

The Impact
This research suggests that even ecosystems that are currently quite cold, such as tundra, will continue to experience greater soil respiration with forecast future warming. Also, many single-site studies have shown an acclimation of soil respiration to warming, but acclimation was not found in this much larger, spatially distributed dataset.

Summary
The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over two decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all non-desert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ˜25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.

Contacts (BER PM)
Scott D. Bridgham
Institute of Ecology and Evolution, University of Oregon
bridgham@uoregon.edu, 541/346-1466

(PI Contact)
Daniel Stover and Jared DeForest
SC-23.1
Daniel.Stover@science.doe.gov (301-903-0289) and Jared.DeForest@science.doe.gov (301-903-1678)

Funding
Since this is a synthesis of many studies, there were many sources of funding. Our funding was from the Office of Biological and Environmental Research, US Department of Energy, Grant DE-FG02-09ER604719.

Publications
Carey et al, “Temperature response of soil respiration largely unaltered with experimental warming.” Proceedings of the National Academy of Science (2016). www.pnas.org/cgi/doi/10.1073/pnas.1605365113

university collaborator; Office of Biological and Environmental Research, US Department of Energy, Grant DE-FG02-09ER604719. No user facility used.

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