Tuesday, February 7, 2012

Amazon comes under fire

Environmental Research Web: The Amazon rainforest stores around 100 billion tonnes of carbon in its biomass, the equivalent of more than 10 years' worth of emissions from fossil fuels. But the region has undergone major changes recently, experiencing deforestation and climate variability. With that in mind, over the last 20 years the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) has looked at some of the processes involved.

"The Amazon region is under multiple pressures simultaneously – land-use change due to agricultural expansion, global climate change, regional climate change induced by the regional land-use change, and widespread use of fire," Eric Davidson of the Woods Hole Research Centre, US, told environmentalresearchweb. "We show how these pressures interact."

...According to Davidson, areas that have already had some forest clearing tend to have more sources of fire ignition in the cleared pastures, slash-and-burn agriculture, and charcoal production activities. "If the climate is drier and the remaining forest under water stress, the fires may spread into forests that had not previously experienced fire," he said. "We also try to sort out these pressures geographically, showing how the greatest changes can already be detected on the southern and eastern flanks of the Amazon, where most change has occurred and where the climate is already naturally dry and getting drier."

..."Brazil has successfully reduced rates of deforestation but not incidence of fire," said Davidson. "One implication is the need to control fire better and to find technologies for pasture management and small-scale agriculture that do not rely on fire."...

In this NASA satellite image of the Amazon near Rondonia, intact forest is deep green, while cleared areas are tan (bare ground) or light green (crops, pasture, or occasionally, second-growth forest). The fish bone pattern of small clearings along new roads is the beginning of one of the common deforestation trajectories in the Amazon.

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