Fire and deforestation processes represented in vegetation models for the Brazilian Amazonia

Abstract

Dynamic global vegetation models need to be improved to accurately represent fire and land-use change in Amazonia. To this end, we are working on improving existent dynamic vegetation models to account for such strong disturbances, and aim to perform new analyses to quantify how fire, deforestation and climate change may combine to affect the distribution of major biomes and climate in the region. At present, we concentrate the development and implementation of new fire models on the simulation of fire probability and effects on vegetation dynamics, based on methods already tested in global dynamic vegetation models where fire potential is driven by the combination of presence of fuel, flammability, and sources of ignitions. To account for fire disturbance we assumed that the fraction of the vegetation affect by fires is proportional to the fire probability. Deforestation is directly interpreted as a fraction of the affected vegetation, and it is assumed to disturb tropical, temperate and conifer broadleaf, evergreen and deciduous trees. Both disturbances affect biomass, leaf area index, and total ecosystem aboveground net primary productivity, modifying the fractional cover of forest and herbaceous canopies. These implementations represent important steps towards the development and use of vegetation models that can account for major contemporary disturbances in the study region.