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The Amazon rainforest is one of the largest, most biodiverse ecosystems on the planet. According to new information published in Geophyscial Research Letters, protecting habitats from development is not only important for the overall health of the rainforest, but for its very existence. It was previously thought that the rainforest would shift to grassland once an area of trees declined by 40 or 50 percent of its original size, but the study finds that the transformation can take place with just a 10 percent decrease.
Grassland replaces rainforest when enough of the tress are lost to create a shift in how evapotraspiration and atmospheric convergence affect rainfall. Fewer trees mean that regions of the rainforest enter a feedback loop where less water reaches the plants, eventually turning them into savannahs and perpetuating their overall decline.
The study’s authors discovered that certain regions of the Amazon reacted differently to changes in precipitation. In some places, it takes a dramatic change in rainfall to convert towering trees to grasses, and in others it can be very minor. Overall, the rainforest’s sensitivity to an equilibrium shift is much higher than previously believed, and in order to preserve the greatest amount of habitat the authors state that 90 percent of existing forest and 40 percent of nearby grasslands must be preserved.
Image Ceasar Paes Barreto