How wildfires increase sensitivity of Amazon forests to droughts

Abstract

The phenology of tropical forests is tightly related to climate conditions. In the Amazon, the seasonal greening of forests is conditioned by solar radiation and rainfall. Yet, increasing anthropogenic pressures (e.g. logging and wildfires), raise concerns about the impacts of forest degradation on the functioning of forest ecosystems, especially in a climate change context. In this study, we relied on remote sensing data to assess the contribution of solar radiation and precipitation to forest greening in mature and fire degraded forests, with a focus on the 2015 drought event. Our results showed that forest greening is more dependent on water resources in degraded forests than in mature forests. As a consequence, the expected increase in drought episodes and associated fire occurrences under climate change could lead to a long-term drying of tropical forests.

Human degradation of tropical moist forests is greater than previously estimated

“…2a , inset). In addition, the increased frequency of extreme droughts may directly increase tree mortality and fire incidence at the edges 34 , 35 , making the first kilometre of the forest edge highly vulnerable to land use and climate change impacts.…”

Drought–heatwave nexus in Brazil and related impacts on health and fires: A comprehensive review

“…Here, we show preliminary results on the synergy between fire activity and CDHW events that further confirm that these hot and dry conditions favor the occurrence of fire. Figure 4 shows the spatial distribution of CDHW conditions (see Supporting Information Other factors can also influence fire activity and may contribute to some of the variability that is not explained by climate extremes, for instance, anthropogenic factors, including political and economic drivers, 191 but also natural factors, such as soil moisture content, 188 and positive fire-climate 192 and deforestation-climate 193 feedbacks.…”

“…Other factors can also influence fire activity and may contribute to some of the variability that is not explained by climate extremes, for instance, anthropogenic factors, including political and economic drivers, 191 but also natural factors, such as soil moisture content, 188 and positive fire–climate 192 and deforestation–climate 193 feedbacks. In particular, the influence of deforestation‐induced feedback on the occurrence, intensity, and frequency of CDHW events should be further investigated, given the observed influence of Amazonia land cover changes on surface temperature, the energy budget, and the hydrological cycle 194 .…”