Climate Sciences Core Capability: Soil Carbon Cycling
LBNL-Earth Sciences Division’s Climate Science Department is a pioneer in carbon cycle research and performs extensive work in soil carbon projects, developing experiments that apply a combination of field and laboratory experiments with advanced analytical techniques that investigate varied aspects of soil carbon cycling and storage. These include study of controls on soil carbon stabilization and destabilization, the natural abundance of radiocarbon (14C), and the labeling of 13C and 15N for decomposition experiments. These experiments are carried out using state-of-the-art LBNL facilities, such as the Advanced Light Source (ALS), for imaging the spatial distribution of organic carbon and nitrogen bound to reactive mineral surfaces, plus a battery of molecular microbiology tools and techniques for detailed investigation of microbial identification and processes in soil.
Isotopic labeling is one type of experiment used in soil carbon cycling and carbon sequestration research. This involves creating and adding isotopically labeled substrates (14C, 13C, 15N) to soils in controlled gradient studies, ecosystem manipulation experiments, or laboratory incubations.
- Systematic, controlled gradients in variables of interest. For example, in the Sierra Nevada, we have studied soils sharing the same climate, dominant vegetation, and stand age, but differing in parent material.
- Ecosystem manipulation experiments. LBNL has established ecosystem experiments manipulating temperature and precipitation. We have also, for example, studied the response of heterotrophic respiration to elevated CO2, warming, and nitrogen and water additions, using the 13C and 14C signature of the elevated CO2 as a tracer.
- Incubation experiments are used to examine decomposition processes in a controlled environment, for example by varying substrate, temperature, or nutrient availability.