Drought and Wildfire Impacts on Carbon and Water Cycles in Terrestrial Ecosystems

Abstract:

As two most prevalent natural disturbances, drought and wildfire occur almost everywhere across the globe, and have been recognized as critical factors in modifying the terrestrial ecosystem structure and functioning. Although wildfires have been widely recognized to be associated with drought events, the combined impacts of droughts and fires on carbon and water cycles in terrestrial ecosystems have not yet been investigated well. To fill this knowledge gap, we examined the interactive impacts of drought and fire disturbances on the terrestrial ecosystem carbon and water cycles by synthesizing climate datasets, fire disturbance datasets, satellite observations, and ecosystem model simulations at both regional and global levels. Our results show that extreme droughts substantially reduced global ecosystem productivity, evapotranspiration, and river discharge. Meanwhile, fire events exacerbate the reductions in ecosystem productivity and carbon storage. Our preliminary results show that global fires reduced global net primary productivity of 4.14 Pg C year^-1 during 1901-2010. Our study further indicates that climate warming in the recent decades induced more extreme drought and fire events, which have threatened the ecosystem capacities for sequestering carbon as well as providing freshwater over many regions of the world.