Soil Biogeochemical Responses of a Tropical Forest to Warming and Hurricane Disturbance

Deciphering how tropical forests will respond to the interacting effects of hurricanes and warming.

The Science

BER supported researchers used a one-of-a-kind tropical forest warming experiment in Puerto Rico to determine how warming affects critical soil processes, such as soil carbon storage, in tropical forests. After a year of warming, Hurricanes Irma and Maria greatly altered the site, allowing us to assess how hurricanes and warming temperatures interact to affect microbes and chemistry for tropical forests soils.

The Impact

This research significantly advanced our understanding of how tropical forest soils respond to warming, to hurricane disturbance, and to the interactive effects of both warming and hurricanes. The work helps us understand and successfully manage these forests into the future, as well as improves our ability to forecast future carbon cycling and climate at the global-scale.

Summary

Tropical forests represent <15% of Earth’s land surface yet support >50% of the planet’s species and play a disproportionately large role in determining climate due to the vast amounts of carbon they store and exchange with the atmosphere. Currently, disturbance patterns in tropical ecosystems are changing due to factors such as increased land use pressure and altered patterns in hurricanes. At the same time, these regions are expected to experience unprecedented warming before 2100. Despite the importance of these ecosystems for forecasting the global consequences of multiple stressors, our understanding of how changes in climate and disturbance will affect tropical forests remains extremely poor. Until now, no studies have evaluated forest recovery following hurricane disturbance within the context of concurrent climatic change. Here, researchers from USGS, USFS, and Michigan Tech present soil results from a tropical forest field warming experiment in Puerto Rico where, a year after experimental warming began, Hurricanes Irma and María greatly altered the forest, allowing a unique opportunity to explore the interacting effects of hurricanes and warming. They tracked post-hurricane forest recovery for a year without warming to assess legacy effects of prior warming on the disturbance response, and then reinitiated warming treatments to further evaluate interactions between forest recovery and warmer temperatures. The data showed that warming affected multiple aspects of soil cycling even in the first year of treatment, with particularly large positive effects on soil microbial biomass pools (e.g., increases of 54%, 33%, and 38% relative to the control plots were observed for microbial biomass carbon, nitrogen, and phosphorus, respectively after 6 months of warming). They also observed significant effects of the hurricanes on soil biogeochemical cycling, as well as interactive controls of warming and disturbance. Taken together, these results showed dynamic soil responses that suggest the future of soil function in this tropical wet forest will be strongly shaped by the directional effects of warming and the episodic effects of hurricanes.

Principal Investigator

Tana Wood
USDA Forest Service, International Institute of Tropical Forestry
tana.e.wood@usda.gov

Program Manager

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

Funding

This research was supported by the U.S. Department of Energy Office of Science Terrestrial Ecosystem Sciences Program (Awards Number 89243018S-SC-000014 and DE-SC- 0011806), the National Science Foundation (DEB-1754713), the USDA Forest Service International Institute of Tropical Forestry (IITF), the University of Puerto Rico-Río Piedras, and the USGS Ecosystems Mission Area.

References

Reed, S. C. et al. "Soil biogeochemical responses of a tropical forest to warming and hurricane disturbance". Advances in Ecological Research 62 225–52   (2020). https://doi.org/10.1016/bs.aecr.2020.01.007.