Drought Drives Rapid Shifts in Tropical Rainforest Soil Biogeochemistry and Greenhouse Gas Emissions

Research findings suggest that tropical forest biogeochemistry is more sensitive to climate change than previously believed.

The Science

Increasing frequency of severe droughts in tropical forests is likely to drive changes in the global carbon cycle. The 2015 Caribbean drought impacted carbon cycling directly via altered greenhouse gas emissions and indirectly via lower phosphorus availability, a limiting nutrient to tropical plant growth.

The Impact

The rapid response and slow recovery to drought suggest tropical forest biogeochemistry is more sensitive to climate change than previously believed, with potentially large direct and indirect consequences for regional and global carbon cycles.

Summary

Climate change models predict more frequent and severe droughts in the humid tropics. How drought will impact tropical forest carbon and greenhouse gas dynamics is poorly understood. Scientists from the University of California, Berkeley, report the effects of the severe 2015 Caribbean drought on soil moisture, oxygen, phosphorus, and greenhouse gas emissions in a humid tropical forest in Puerto Rico. Drought significantly decreases concentrations of inorganic phosphorus, an element commonly limiting to net primary productivity in tropical forests, and significantly increases organic phosphorus. High-frequency greenhouse gas measurements show varied impacts across topography. Soil carbon dioxide emissions increase by 60% on slopes and 163% in valleys. Methane (CH4) consumption increases significantly during drought, but high CH4 fluxes post drought offset this sink after seven weeks. The rapid response and slow recovery to drought suggest tropical forest biogeochemistry is more sensitive to climate change than previously believed, with potentially large direct and indirect consequences for regional and global carbon cycles.

Principal Investigator

Whendee Silver
University of California, Berkeley
wsilver@berkeley.edu

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
daniel.stover@science.doe.gov

Funding

U.S. Department of Energy grant to W.L.S. (TES-DE-FOA-0000749).
National Science Foundation grant to W.L.S. (DEB-1457805).
National Science Foundation Luquillo Critical Zone Observatory grant (EAR-0722476) to the University of New Hampshire.
National Science Foundation Luquillo Long-Term Ecological Research grant (DEB-0620910) to the University of Puerto Rico.

References

O’Connell, C. S., L. Ruan, and W. L. Silver. "Drought drives rapid shifts in tropical rainforest soil biogeochemistry and greenhouse gas emissions". Nature Communications 9 1348  ((2018)). https://doi.org/10.1038/s41467-018-03352-3.