Wildfires decrease the local-scale ecosystem spatial variability of Pinus canariensis forests during the first two decades post fire

Abstract

The spatial variability (i.e. heterogeneity) of environmental variables determines a wide range of ecosystem features and plays a key role in regulating key ecosystem services. Wildfires are among the most significant natural disturbances that forests face, but our knowledge about their effect on ecosystem spatial variability is still limited. We used a 19-year fire chronosequence of natural, unmanaged Pinus canariensis C. Sm. ex DC forests to investigate how wildfires affect overall ecosystem spatial variability, as well as that of key faunal, plant and soil ecosystem attributes. The spatial variability of most soil variables and of the overall ecosystem tended to decrease after the fire and remain lower than the unburned plots even after 19 years. The spatial variability of plant-related variables, except for litter decomposition, as well as that of soil arthropods abundance, decreased more gradually than that of soil variables, reaching the lowest values in the plots burned 19 years before the survey. Our study provides evidence that wildfires are capable of significantly decreasing local-scale forest spatial heterogeneity through changes in the spatial variability of their different components, with likely yet unknown consequences for ecosystem functioning.