Monitoramento , modelagem e efeitos do fogo no nordeste da Amazônia

Abstract

Changes in natural fire regimes in the Amazon can affect the sustainability of forests and savannas. However, there is a lack of knowledge about the causal determinants and the effects of different fire regimes on the biodiversity of ecosystems in northeastern Amazonia. In addition, there are disagreements about what could happen with fire activity in future climate change scenarios. This study aimed to: (i) synthesize previous research efforts in Fire Ecology and Remote Sensing (RS), through scientometric analysis and connection networks; (ii) model the recent spatial distribution of fire propensity, by the maximum entropy method (MaxEnt), identifying the main drivers; (iii) project the future “niche of fire” in two contrasting scenarios of global warming, considering the data from the CNRM-CM6-1 model for the next decades and for the end of this century; and (iii) to analyze how different fire recurrences may have affected the structure and diversity (taxonomic and functional) of savannas, through the interpretation of generalized additive mixed models (GAMM). The scientometric analyzes allowed us to identify that RS and Fire Ecology are sciences that evolved over time in a complementary way, contributing to expand studies in biodiversity, conservation and environmental monitoring. Our fire probability models have shown that ignition is more common in savannas than forests due to the synergy of socioeconomic and environmental factors. However, in the long term, shifts towards a warmer and drier climate could result in a large regional expansion of fire-prone areas. Finally, we found that in savannas the taxonomic diversity reaches maximum levels in landscapes under intermediate fire frequency regimes. The increase in fire frequency may be resulting in the loss of species that play redundant functional roles and there may still be the entry of new species of grasses and herbs favored by this disturbance. Therefore, despite not decreasing functional richness, fire modifies functional diversity. We conclude that at local scales the high frequency of fires reduces biological diversity, an impact that in the long term may be irreversible, especially if climate change converges to scenarios of greater global warming.