Written by Joshua S. Hill

A massive storm swept through the Amazon Forest in early 2005 and killed half a billion trees as it went.

A new study has shown that the long line of severe thunderstorms which swept through the Amazon in January of 2005 took down between 441 and 663 million trees. Though not the first time storms have been thought responsible for such widespread deforestation, it is the first time an actual body count has been provided for a particular storm.

And the losses are much greater than had previously been suspected, the authors of the study say, which suggests that storms play a much larger role in the dynamics of the Amazon forest than had been previously recognized.

In 2005 a series of severe thunderstorms, those associated with lightening and heavy rainfall, known as a squall line, swept through the Amazon rainforest. From January 16 to January 18 a squall line 1,000 (620 miles) long and 200 kilometres (124 miles) wide crossed the Amazon basin from southwest to northeast. Several human deaths were reported in the cities of Manaus, Manacaparu and Santarem. The storms wind speeds reached up to 145 km/hour (90 mil/hour) and unrooted or snapped in half trees that were in its path. Not surprisingly, the trees often took down their neighbours as well.

Using a combination of Landsat satellite images from the Manaus region, field-measured tree mortality, and modelling to determine the number of trees killed by the storm, they were able to calculate the number of trees the storm had taken down in that region.

Hand counting trees that had been downed, researchers were able to distinguish what trees had been blown down during the storm and what trees had died due to a drought which had taken place at the same time. “If a tree dies from a drought, it generally dies standing. It looks very different from trees that die snapped by a storm,” said Jeffrey Chambers, a forest ecologist at Tulane University, in New Orleans, and one of the authors of the paper.

The information gathered in the Manaus region allowed them to calculate that between 300,000 and 500,000 trees had been downed in the region due to the storm. With this information they then extrapolated the results out for the whole Amazon basin to calculate how many trees had been killed as a direct result of the storm.

“We know that the storm was intense and went across the basin,” Chambers says. “To quantify the potential basin-wide impact, we assumed that the whole area impacted by the storm had a similar level of tree mortality as the mortality observed in Manaus.”

Source: http://planetsave.com/blog/blog/2010/07/13/storm-killed-half-a-billion-trees-in-amazon/

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