Fire effects on carbon and nitrogen cycling in forests of the Sierra Nevada

Abstract

Fire removes substantial quantities of nitrogen (N) by volatilization, and prescribed fire, over time, can remove as much as or more N than wildfire. This lost N can be quickly made up if fire is followed by N₂-fixing vegetation. Wildfire often has short-term deleterious effects on water quality because of N mobilization, but long-term fire suppression allows buildups of N-rich litter, a source of labile N to runoff waters. Prescribed fire usually has less impact on water quality than wildfire. Prescribed fire has been proposed as a management tool to mitigate N saturation (a result of chronic, excessive N deposition). However, a major limitation of this strategy is that while fire removes substantial quantities of N from the forest floor, it removes only a small fraction of the large N reservoir in the mineral soil and at the same time causes increases in soil ammonium over the short term. Periodic prescribed fire, reduced atmospheric N deposition and strategies to enhance plant and microbial N demand may all be required to reduce N-saturation symptoms in catchments exposed to long-term atmospheric N inputs.

Parent Publication

• Wildland fires and air pollution. Developments in Environmental Science 8

Citation

Johnson, D.W.; Fenn, M.E.; Miller, W.W.; Hunsaker, C.T. 2009. Fire effects on carbon and nitrogen cycling in forests of the Sierra Nevada. In: Bytnerowicz, Andrzej; Arbaugh, Michael; Andersen, Christian; Riebau, Allen 2009. Wildland Fires and Air Pollution. Developments in Environmental Science 8. The Netherlands: Elsevier: p. 405-423