Fire Risk High in Thirsty Amazon Rainforest
11/13/98
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Title: Fire Risk High in Thirsty Amazon Rainforest
Source: Environmental News Service (ENS)
Status: Copyright 1999, contact source for permission to reprint
Date: November 13, 1998
WOODS HOLE, Massachusetts, November 13, 1998 (ENS) - Unusually low
amounts of rainfall in 1998 have increased the area of Amazon
rainforests vulnerable to fire to more than one million square
kilometers (386,000 square miles), or one third of the forests of
Amazonia.
Contrary to media reports, there have been hundreds of Amazon forest
fires in 1998, forest fire researchers from Brazil and the United
States report.
In May, researchers of the Instituto de Pesquisa Ambiental da
Amazonia, a non-governmental research institute based in Belem,
Brazil, and the Woods Hole Research Center, based in Massachusetts,
predicted that about 400,000 square kilometres (154,440 square miles)
of forest in the Brazilian Amazon would become vulnerable to fire
during the 1998 dry season.
An update of this fire prediction based on aerial and field studies
has more than doubled that estimate.
The most recent study was conducted in September, in a 300 x 150
kilometre area that extends from Marab south to Redenao, in Para
State. It is located in the southeastern corner of Brazil's "arc of
deforestation," near the edge of the Amazon forest.
Scientists based their estimate on 1,110 observations made from a
low-flying airplane along an 800 kilometres (500 mile) flight path
that criss-crossed the region, combined with field visits to burned
and unburned forests, according to Dr. Daniel Nepstad of the Woods
Hole Research Center.
At a meeting in Brasilia next week Dr. Nepstad will present the latest
research findings to officials of USAID and others. The driest time of
year in the area studied is right now. Rains should arrive in the
northeastern part of the basin by early to mid-December. But in 1997,
only about half the predicted amount of rain actually fell.
Forests in which ash was observed on the ground, or in which leaves
were scorched brown from flames, were recorded as burned. Burned
forests were recorded at nine percent of the observation points.
Although this study was conducted in a region that is highly prone to
forest fires because of severe drought, these results are of major
significance for estimates of human damages to Amazon forests, and of
carbon emissions from Amazon forests associated with land use
practices Dr. Nepstad said.
Using additional rainfall data collected across the region, Woods Hole
researcher Paul Lefebvre told ENS the forest remained drier than
normal and very hot. Researchers are mapping much larger areas of
severe flammability than last year based on meterological conditions
reported by the World Meteorological Organization.
Researchers calculate that more than one half of this drought-stressed
forest (700,000 square kilometres or 270,000 square miles) had
depleted all available soil water to five meters (16 feet) depth by
the end of September.
In the first field study conducted to test this prediction, the
researchers measured the amount of fire-vulnerable forest that
actually caught fire in a small test region in southeastern Amazonia.
They discovered that three to five thousand square kilometers of
standing forest caught fire in 1998 in this region. This area of
burned forest is one-fifth the size of the entire forest area that is
"deforested" through clear-cutting and burning each year - average is
19,000 square kilometres per year - as measured by the Brazilian
Government's deforestation monitoring program.
And yet, the burned forests were documented within a very small region
that is less than one percent of the legal Amazon - 5,000,000 square
kilometres (1.93 million square miles).
map Recent field studies show the burning of standing forest can
release 10 to 80 percent of forest biomass to the atmosphere as heat-
trapping carbon dioxide.
The burning of standing forests is not currently included in the
government's monitoring program. So, forest fires such as those
observed between Marab and Redenao release large amounts of carbon
dioxide to the atmosphere that are not included in current estimates
of carbon emissions from Amazonia.
c Environment News Service (ENS) 1998