Impact of fire on soil gross nitrogen transformations in forest ecosystems

Abstract

Forests play a key role in the global carbon (C) and nitrogen (N) cycling. Fire is a global phenomenon occurring in many forest ecosystems, which has several environmental and ecological effects. The objective of this review was to improve our understanding of the effect of fire on soil gross N transformations in forest ecosystems. We have reviewed the published studies using 15N pool dilution technique with analytical data analysis method to study the effect of fires on gross N transformations in forest ecosystems. Wildfires increased gross N mineralization rates in the short term and the effect disappeared from 3 years after the fire, while the effect of prescribed fires disappeared from 2 years after the burning. Both wildfires and prescribed fires reduced gross nitrification in the short term, while their effects varied from 6 months following the burning. The different responses of gross N transformations to the fires in forest ecosystems depended on many factors including forest types, the intensity and frequency of fires, the time elapsed between the fires and sampling events, incubation conditions (field or laboratory incubation), climatic conditions and so on. In view of many factors influencing the effect of fires on gross N transformations, more comprehensive studies with physical, chemical, microbial and ecological characterization are needed to improve our knowledge about the effect of fires on soil gross N transformations and then N cycling in forest ecosystems.