Drought makes rainforest greener - September 21, 2007
In one to file squarely under the ‘you what?’ heading researchers have found that a major drought made the Amazon greener, not browner. Satellite observations showed a ‘green-up’ in response to an intense drought in 2005. “These findings suggest that Amazon forests, though threatened by human-caused deforestation, fire, and possibly by more severe long-term droughts, may be more resilient to climate changes than ecosystem models assume,” according Scott Saleska and colleagues’ Science paper (abstract).
Some models predict that global warming could kill off the Amazon rainforest by causing “intense drought” (Live Science). The forest should respond to drought by cutting evaporation from its leaves and cutting photosynthesis. In a feedback loop this reduces the amount of water in the atmosphere, perpetuating the drought.
Actually, during the 2005 drought trees used water from deep roots to take advantage of the cloudless skies and have a bit of a growth spurt, explains the Arizona Daily Star. “If you anthropomorphize a little bit these trees are not dumb. They’ve been living here tens of millions of years,” Saleska, an ecologist at the University of Arizona, told the paper. However this only works for a while. “You take away enough water for a long enough time, the trees are going to die,” he adds.
There is a wonderful extended feature on the whole issue from last year on NASA’s Earth Observatory website.
Image: Getty
