NH010-03
Disentangling burned area drivers over the Brazilian savanna

Tuesday, 8 December 2020: 05:45
Virtual
Patrícia S. Silva1, Renata Libonati1,2, Filippe L.M. Santos2, Julia A. Rodrigues2, Joana Nogueira2 and Carlos DaCamara1, (1)Instituto Dom Luiz (IDL), Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Lisboa, Portugal, (2)Departamento de Meteorologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
Recorded Presentation
Abstract:
Growing under hot and seasonally dry climatic conditions, the Brazilian savanna - Cerrado - is a fire-prone biome responsible for more than 50% of Brazil’s annual burned area (BA). It covers a total area of 2 million km2 and it is highly heterogeneous. While studies evaluate Cerrado as a whole or focus on small extents of the biome, a regional characterization of fire drivers is still lacking.

Here, the Cerrado is partitioned into 19 ecoregions with unique landscape traits and, for each, we evaluate BA and the number of fire occurrences from the Global Fire Atlas (GFA) along with BA from the MODIS MCD64A1 product. We further study their relationship with climate, using the Fire Weather Index (FWI, estimated with ERA5 meteorological data), and several human components that include farming and urban areas, using the regionally-tailored MapBiomas v4.1 product, and population density. Simple and multiple linear models were fitted, and the goodness of fit evaluated by the coefficient of determination.

Climate was consistently found to be the main driver of interannual BA in all ecoregions except for three where the human component plays a prominent role. When applying multiple regression models, we found that there is an added value when modelling interannual BA with both climate and human components in all ecoregions (all models but one explain more than 50% of the variance).

Furthermore, data from GFA was stratified into four categories according to scar size: very small (< 100 ha), small (100-1000 ha), medium (1000-5000 ha) and large (> 5000 ha). Results show that the number of fire occurrences of the large class is much more correlated with climate than with any human component in all ecoregions, confirming climate as the main driver behind high burned areas. Conversely, the number of very small and small scars are equally correlated with climate and human components.

These results contribute to a deeper understanding of regional fire dynamics in Cerrado and pave the way to further improve modelling fire activity in this biome.

This study was funded by Fundação para a Ciência e a Tecnologia (FCT, SFRH/BD/146646/2019), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ, 305159/2018–6, 380779/2019-6, 381461/2018-1, 441971/2018–0) and Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ, 202.714/2019).

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