The Amazon’s most fertile, productive forests, which are critical for supplying Brazil’s agricultural region with rainfall, are also the most vulnerable to drought, according to recent research that has mapped drought resilience across the basin. An international team of researchers analyzed 20 years of satellite data to understand why some forests might be more resilient to drought than others and focused on the underlying mechanisms behind different responses of forests across the basin. The study, published in Nature, used water-table depth, soil fertility and tree height to define different intact forest ecotopes in the Amazon and looked at how much growth and photosynthesis was happening in these ecotopes during “once-in-a-century”, major drought events in 2005, 2010 and 2015. Results showed that forests behaved differently according to their position in the basin. In forests with deep water tables, such as Brazil’s Tapajós National Forest, tall trees with deeper root networks are more resilient to droughts. Image courtesy of Tyeen C. Taylor. In the southern Amazon, where soil fertility tends to be high, researchers found a strong relationship between groundwater availability and the forests’ resilience to drought. Shallow water tables, where soil water is plentiful even in the dry season, protected the forests from the harmful effects of droughts. This allowed forests to thrive during short droughts, by taking advantage of the additional sunlight and increased availability of oxygen to their roots. The result was an overall greening effect in shallow-water-table forests during moderate droughts. Forests’ responses to drought were more complex…This article was originally published on Mongabay
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