Peatland ecosystems
LLNL researchers are part of a multi-institutional Department of Energy‒funded research project focused on evaluating how long-term environmental changes impact peatland forests—carbon-rich ecosystems that store and sequester more carbon than any other type of terrestrial ecosystem. The Spruce and Peatland Responses Under Changing Environments (SPRUCE) research site in northern Minesota has ten open-topped experimental enclosures that allow scientists to manipulate the temperature and concentration in the air. Scientists then study how changing these two variables impacts carbon uptake, peat decomposition, and carbon release.
SPRUCE provides an opportunity for researchers to observe changes in a natural environment that can’t be replicated at smaller scales in the laboratory. Results indicate that elevated temperatures increase the vegetation’s uptake of carbon, while also causing the peat to produce more carbon dioxide and methane, and reducing the peatland’s ability to store carbon.
Key collaborator: Oak Ridge National Laboratory
What’s next: In addition to ongoing involvement in the SPRUCE project, LLNL scientists are expanding their research into other types of terrestrial wetlands, such as prairie potholes in North Dakota. A major goal of these projects is increasing our confidence in Earth system models.
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The soil microbiome
The “Microbes Persist: Systems Biology of the Soil Microbiome” project, funded by the Department of Energy (DOE) and led by LLNL, includes a multidisciplinary research team, with experts in soil microbiology, biogeochemistry, bioinformatics, and ecosystem modeling. They are exploring which functions of soil-based microorganisms are most relevant to keeping carbon in the soil, as well as how soil moisture affects this biosequestration process. In addition, they are exploring how soil-based microbial communities change with soil depth, and how the stress of long-term environmental changes alter what is growing and dying in these communities.
Researchers leverage the isotopic analysis capabilities offered at CAMS to identify the age and source of soil carbon samples. Findings provide insight regarding how changes in the environment can impact long-term soil carbon storage.
Key collaborators: Lawrence Berkeley National Laboratory, Pacific Northwest National Laboratory, Northern Arizona University, the University of Minnesota, and the University of California, Berkeley
What’s next: As part of the ongoing Microbes Persist project, scientists from LLNL and collaborating institutions are focusing on how microbes transform plant carbon into compounds that serve as the building blocks for persistent soil organic carbon. Scientists are also exploring microbial cycling of carbon and nutrients within ecosystems with more complex plant communities and integrating this new knowledge into simulation models.
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Wildfires and soil-based carbon sequestration
LLNL scientists and their collaborators are exploring how the intensity and frequency of wildfires affect carbon cycling and storage in soil. LLNL soil biogeochemistry, paleoclimatology, and geochronology experts teamed up with representatives from the Karuk Tribe’s Department of Natural Resources to study soil in Karuk homelands. Tribal representatives share their knowledge of cultural practices that use “good fire” for landscape management and ceremonial purposes, which can help maintain healthy forests that are supported by healthy soil.
The research team collected soil samples at four sites along the Klamath River region in California:
- A site that has not experienced a fire in more than 100 years due to fire suppression
- A site that has experienced low-intensity, regular fires in recent years
- A site that has experienced low-intensity burning as part of the Karuk Tribe’s efforts to re-establish traditional burning patterns
- A site that recently experienced high-intensity wildfire
The research team analyzed soil samples using radiocarbon analytical capabilities at CAMS, as well as LLNL's nuclear magnetic resonance facility. Results indicate that traditional land management practices used by indigenous peoples—informed by their deep multi-generational knowledge of their landscape and using fire as a tool—can be used to foster healthier forests that are less prone to catastrophic wildfires.
Key collaborator: Department of Natural Resources, Karuk Tribe
What’s next: LLNL scientists hope to build on this research as they explore the connections between temperature, fuel type, and fire frequency and the types of molecules in the soil (e.g., lipids and proteins). In addition, related research at LLNL regarding cosmogenic nuclides may make it possible to explore a site’s fire history dating back hundreds to thousands of years by examining different isotopes in the mineral fraction of soils.
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Additional project examples
Today’s carbon cycle research at LLNL that focuses on terrestrial ecosystems was built on a long history of related research at the Laboratory. For example, our scientists leveraged the analytical capabilities offered at CAMS to study carbon cycles in the following environments:
- Tropical forests. Scientists studied the role that moisture plays in soil carbon storage and turnover in tropical forests, providing insight regarding how this soil-based carbon may respond in a warmer and drier future environment. Findings imply that both warming and drying will accelerate the loss of older soil carbon and reduce the incorporation of fresh carbon inputs, thereby negatively impacting carbon storage in tropical forests. In addition, they studied how rapid deforestation in tropical forests impacts the stability of soil-based carbon.
- High-elevation forests. Forest ecosystems at higher elevations tend to store organic carbon in soil deep below the surface. Scientists explored the dynamics of solid-based carbon pools located at a depth of 10 meters, with findings indicating that more than 75% of soil-based carbon stored in these environments is found below 30 centimeters, in deep soil and weathered bedrock. In addition, this deep soil carbon is a mixture of very old and actively cycling carbon, suggesting that a portion of this pool may be vulnerable to long-term environmental changes.
- Permafrost. Elevated temperatures are increasing the seasonal thaw of permafrost, making the extensive carbon stock sequestered in these environments vulnerable to decomposition and loss back into the atmosphere. LLNL scientists studied the age and chemistry of dissolved organic carbon in water that drained from permafrost environments in northern Alaska, with findings indicating that increasing amounts of older carbon will be released into the atmosphere as elevated temperatures increase permafrost thaw.
