Picture description:Heated soils in the Soil Warming Experiment in Lowland Tropical Rainforest (SWELTR). A control plot (left) the soil is at ambient temperature, in a heated plot (right) the entire soil profile is heated by 4oC. We are using the experiment to understand how future climate warming will affect tropical forest soil processes, communities and biogeochemical cycles.

Project title

Hot Gas from the Deep: Understanding how soil warming and seasonal rainfall transitions affect carbon dioxide and methane emissions from deep soils in a tropical forest.

Mentor's name(s)

Martijn Slot , Staff Scientist

Co-mentor's name(s)

Andrew Nottingham, Assistant Professor University of Leeds/ STRI Research Associate

Location of internship. Will mentor be at this location?

Barro Colorado Island and Panama City (Tupper). Mentor and co-mentor will be present at both locations to supervise as required.

Project summary

Climate change threatens to affect ecosystem carbon cycling, with large consequences for the future atmospheric greenhouse gas concentration and further climatic change. This effect could be especially large in tropical soils, which contain a third of global soil carbon stores and where high metabolic rates mean that carbon is rapidly cycled by decomposer communities. Climate warming has been shown to increase the release of carbon dioxide (CO2) in tropical soils, but we lack information on how warming will affect another important greenhouse gas, methane (CH4), which accounts for 16-25% of current atmospheric warming. Almost half of global CH4 emissions are from natural origin, released by methanogenic microorganisms. However, in tropical soils there is also high activity of methanotrophic microorganisms, which can consume CH4 through oxidative reactions. The consumption and production of CH4 (alongside CO2) can also strongly vary with depth in the soil profile and with seasonal transitions in rainfall, due to variation in microbial communities and activity, soil moisture and soil oxygen availability. This project addresses the specific question of whether warming in tropical soils will affect the release of both carbon dioxide (CO2) and methane (CH4). The project will specifically test the hypotheses that under warming there is high production of CO2 and CH4 released from deep soils, and that the release of these greenhouse gases is higher during seasonal transitions towards wetter conditions. The outcome of these different processes will have major consequences for the future climate. In this project, the intern will use a unique soil-profile warming experiment (SWELTR) to test these hypotheses.

Mentorship goals

The goal of the proposed project is to determine the emissions of CO2 and CH4 from different depths in the soil profile in the Soil Warming Experiment in Lowland Tropical Rainforest (SWELTR project) on BCI. The measurements will be conducted using an infra red gas analysers and using a gas-well methods. To determine how soil properties are related to the emissions of these gases, further measurements of soil chemistry (nutrients, carbon composition, pH) will be made for the soil profile.
At the end of the project the intern will be fully trained in using infra red gas analysers to measure gas flux exchange. The intern will also receive training in basic laboratory analyses for carbon and nutrient extractions, performed in the biogeochemistry laboratory. The intern will receive further training in experimental design, basis statistical analyses and report writing.

Intern’s role, time commitment and expected products

The intern will be working alongside Dr. Slot and Dr. Nottingham. They will receive further support from SWELTR technician Alicia Sanjur. The time commitment will be full time over 3 month period, with expected time allocation of 50% field work (BCI), 30% laboratory work (Tupper) and 20% analyses and writing. It is expected that by the end of the internship period, an informal report is produced and presented to the mentors on the results and outcomes (to be later developed into or incorporated into a scientific publication).

Regularly held occasions for group discussions, attendance at lectures, career counseling, and other educational and experiential opportunities for interns

The intern attend a weekly project group meeting for discussion and feedback (with both mentors present), and will have daily supervision from the project team. The intern will have the opportunity to attend Bambi and Tupper seminars (weekly). The mentors will discuss the project and outcomes with the intern to ensure that they are receiving the training that is targeting specific needs for the intern to progress in their scientific career (e.g. experimental design, analytical skills), and to provide guidance on their next scientific career steps (e.g. PhD programs).

List of suggested readings

Nottingham AT, Meir P, Velasquez E, Turner BL (2020) Soil carbon loss from a tropical forest in response to in situ experimental warming, Nature 584 (7820), 234-237

Nottingham AT, Gloor E, Bååth E, Meir P (2022) Soil carbon and microbes in the warming tropics Functional Ecology 36, 1338–1354

Nottingham AT, Montero-Sanchez M, Slot M, Szczygieł H, Velasquez E, Meir P (2023) Seedling growth declines in warmed tropical forest soils. Biotropica, 55, 897-910 31

Nottingham AT, Scott J, Saltonstall K, et al. (2022) Microbial diversity decline and community adaptation in warmed tropical soils do not explain soil CO2 emission Nature Microbiology 7 (10), 1650-1660

Singh, B. K., Bardgett, R. D., Smith, P., and Reay, D. S. (2010). Microorganisms and climate change: terrestrial feedbacks and mitigation options. Nat. Rev. Microbiol. 8, 779–790. doi: 10.1038/nrmicro2439

Zhao, JF., Peng, SS., Chen, MP. et al. Tropical forest soils serve as substantial and persistent methane sinks. Sci Rep 9, 16799 (2019). https://doi.org/10.1038/s41598-019-51515-z