Charred wood remaining after a wildfire as a reservoir of macro- and micronutrients in a Mediterranean pine forest

Large amounts of logs and coarse woody debris remain in the ecosystem after wildfires. However, the relevance of the nutrient reservoir contained in the remaining post-fire woody debris for the ecosystem nutrient reserves is rarely considered. In this paper, we determine the carbon and nutrient concentrations in the partially charred wood after a wildfire along an altitudinal gradient and assess the relative magnitude of the nutrient reservoir in the wood in relation to those existing in the first 10-cm soil layer. Soils were poorly developed and nutrients limiting for the vegetation requirements. Charred woody material still contained a relatively high concentration of nutrients compared to those reported for unburnt pine wood, and in general, this decreased with altitude. Partially charred wood represented a considerable pool of nutrients, due to both the relatively high concentrations and to the great amount of biomass still present after the fire. Potential contributions of the charred wood were particularly relevant for N and micronutrients Na, Mn, Fe, Zn and Cu, as wood contained 2-9 times more nutrients than the soil. Post-fire woody debris constitutes therefore a valuable natural element as a potential source of nutrients, which would be lost from ecosystems in cases where it is removed.