Spatial Pattern of the Seasonal Drought/Burned Area Relationship across Brazilian Biomes: Sensitivity to Drought Metrics and Global Remote-Sensing Fire Products

Abstract

Fires are complex processes having important impacts on biosphere/atmosphere interactions. The spatial and temporal pattern of fire activity is determined by complex feedbacks between climate and plant functioning through and biomass desiccation, usually estimated by fire danger indices (FDI) in official fire risk prevention services. Contrasted vegetation types from fire-prone Brazilian biomes may respond differently to soil water deficit during the fire season. Then, we propose to evaluate the burned area (BA)/FDI relationship across Brazil using most common FDIs and the main BA products from global remote sensing. We computed 12 standard FDIs-at 0.5 • resolution from 2002 to 2011 and used the monthly BA from four BA datasets-from the MODIS sensor (MCD45A1), the MERIS sensor (MERIS FIRE_CCI), the Global Fire Emission Database version 4 (GFED4) and version 4s including small fires (GFED4s). We performed a Principal Component Analysis (PCA) on the coefficients of determination (R 2 ) of the FDI/BA relationship to investigate the biome specificities of Brazilian biomes and the sensitivity to BA datasets. Good relationships (R 2 > 0.8) were observed for all BA datasets, except SPEI (R 2 < 0.2). We showed that FDIs computed from empirical water balances considering a lower soil capacity are more correlated to the seasonal pattern of fire occurrence in the Cerrado biome with contrasted adjustments between the western (early drying) and eastern part (late drying), while the fine fuel moisture index is more correlated to the fire seasonal pattern in Amazonia. The biome specificities of the FDI/BA relationship was evaluated with a general linear model. High accuracies in the biome distribution according to the FDI/BA relationship (>50%, p < 0.001) was observed in Amazonia and Cerrado, with lower accuracy (<32%, p < 0.001) in the Atlantic Forest and Caatinga. These results suggest that the FDI/BA relationship are biome-specific to explain the seasonal course of burned in Brazilian biomes, independently of the global BA product used. Selected FDIs should be used for fire danger forecast in each Brazilian biome.

Simulating the effects of weather and climate on large wildfires in France

“…Finally, we used the more sophisticated soil wetness index (SWI) developed by CNRM (Centre National de la Recherche Météorologique). This last index was derived from ISBA (Noilhan and Mahfouf, 1996), a soilbiosphere-atmosphere interaction model based on soil characteristics across France, reflecting the moisture available for the plants. The SWI integrates the propagation of moisture from the superficial surface layer to the root zone (Barbu et al, 2011).…”

Spatiotemporal Patterns and Phenology of Tropical Vegetation Solar-Induced Chlorophyll Fluorescence across Brazilian Biomes Using Satellite Observations

“…Figure 1 shows the Brazilian biome limits utilized in this study. These biomes are used as a large spatial scale basis for comparisons of the high resolution satellite-based SIF measurements across regions for the whole country of Brazil, which covers an area of about 850 million ha [103]. Table S1 shows a list of all abbreviations used in the study.…”

“…Despite often being referred to as a desert, the Caatinga is a semi-arid region, making up about 10% of the country, has only about 700 mm of rainfall per year, falling sometimes erratically with high temperatures and low humidity [116,117]. and the dominant vegetation is woody shrub land and savanna with abundant xerophytic species, but contains mosaics of seasonally dry tropical forests and is one of the most populated semi-arid regions of the world [96,103,[116][117][118][119]. The Atlantic Forest covers a wide longitudinal area and has been heavily fragmented to only about 10% of the native vegetation remaining after once having about 150 million ha of rainforest [88,120].…”

Changing Weather Extremes Call for Early Warning of Potential for Catastrophic Fire

“…Abatzoglou and Kolden () found the fine fuel moisture code (FFMC), which is embedded within the FWI, to explain 54% of fire season BA in forest environments of Northern California, but no generic model for the western United States. Nogueira et al () report moderate to strong correlations between several fire danger indices, including FWI and FFDI, and monthly BA for four biomes in Brazil. Tian et al () however, found that FWI, or the FFMC, explained only a small fraction of variation in BA in forests of the Daxing'anling region of northern China.…”