SOIL CARBON AND NUTRIENT RECOVERY AFTER HIGH-SEVERITY WILDFIRE IN MEXICO

Fire severity can increase above historical levels due to factors such as human-derived fire suppression and climate change. Studies about the effects of high-severity fires on soil carbon and nutrients in pine forest at tropical latitudes are still rare. We analyzed the changes in carbon (C), nitrogen (N), and phosphorus (P) contents in the organic layer and the top mineral soil layer in a post-fire chronosequence of Pinus douglasiana Martinez-dominated forest stands in central-western Mexico 8 yr, 28 yr, and 60 yr following a high-severity fire. We found that fire significantly affected the total C, N, and P contents in the organic layer, explained mainly by mass losses. We did not detect differences in C, N, and P contents (Mg ha(-1)) in the mineral soil, but C and N concentrations (mg g(-1)) increased with stand age. This can be explained by the high levels of tree mortality that occur during high-severity fires, depleting litter inputs to the soil. We observed a fast recovery of C, N, and P, perhaps resulting from the high capacity of Pinus douglasiana to regenerate following high-severity fires. This can be associated with high metabolic rates of forests in tropical latitudes, which, given their climate and soil conditions, favor higher rates of vegetation growth and, thus, faster rates of organic C inputs and soil organic C accumulation.