Fire effects on carbon and nitrogen cycling in forests of the Sierra Nevada
This article is part of a larger document. View the larger document here.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.