How do plants and soil sequester carbon?
Terrestrial (land) ecosystems remove atmospheric carbon dioxide by plant photosynthesis during the day, which results in plant growth (roots and shoots) and increases in microbial biomass in the soil. Plants release some of the stored carbon back into the atmosphere through respiration. When a plant sheds leaves and roots die, this organic material decays, but some of it can be protected physically and chemically as dead organic matter in soils, which can be stable for up to thousands of years. The decomposition of soil carbon by soil microbes releases carbon dioxide to the atmosphere. This decomposition also mineralizes organic matter, which makes nutrients available for plant growth. The total amount of carbon stored in an ecosystem reflects the long-term balance between plant production and respiration and soil decomposition. Source: Oak Ridge National Laboratory (ORNL) http://www.ornl.gov/info/ornlreview/rev32_3/earth.
