Wildfire Charcoal and Soil Processes

Wildfire Charcoal and Soil Processes
Thomas H. DeLuca, Adjunct Professor of Forest Soils, tom.deluca@cfc.umt.edu

Working with colleagues in Sweden and Montana, we have been studying charcoal, that is formed during fire events, to evaluate its role in forest ecosystem processes. Under support from the NSF-DEB-Ecosystems program, we have found that the naturally formed charcoal enhances nitrification in forest soils that do not normally exhibit net nitrification. Working with Bill Holben’s laboratory we have found that fire induces a significant shift in the nitrifier community and believe that much of this shift relates to the incorporation of charcoal during fire events. Further, charcoal has proven to be extremely effective in the adsorption of phenolic and terpenoid compounds which in turn may influence plant-plant, plant-soil, and plant-microbe interactions. Charcoal deposited during fire has the potential to influence soil processes by acting as a safe site for microbial activity or by “sponge” for organic compounds released directly from plant leaves and roots or by the decomposition of plant litter. Charcoal exhibits a unique longevity in soils, having turnover times of 3,000 to 12,000 years. This means that charcoal deposited enters directly into the “passive” soil C pool meaning that it functions as a long-term store of ecosystem C. Given the high capacity to sorb organic materials, charcoal may also function as a seed for humus formation.