NASA Science News for May 16, 2003

Mesoamerica Burning

Part 1 of 2

The rich diversity of wildlife in southern Mexico and Central America
is in peril. Local governments are using satellites to get a grip on
a vast "corridor" system of protected lands. 

May 16, 2003: Central America is on fire.

In an area of rich biodiversity, where 7% of our planet's terrestrial
species are packed onto less than 1% of the planet's land, a rapidly
growing human population is struggling with widespread poverty that
affects more than 20 million people. Many of these people survive
through unsustainable "slash and burn" agriculture, putting
themselves and the rain forest on a collision course with
catastrophe.

Simultaneously promoting the local economy while protecting forests
and wildlife is the ambitious goal of an international project called
the Mesoamerican Biological Corridor (CBM is the acronym for the name
in Spanish). 

The largest "sustainable development" effort of its kind in the
world, the CBM is a sprawling web of protected and semi-protected
lands that stretch the entire length of Central America from southern
Mexico to the border of South America--a region known as "
Mesoamerica." The lands of the CBM are collectively managed by the
governments of the seven Central American countries and Mexico.
Together, these governments preserve some areas of the CBM and in
others promote limited, "sustainable" economic use of the land. 

Ecology and economy: a star-cross'd marriage?

"The human dimension is now one of the most important factors for not
only conservation but also sustainable economic development," says
Daniel Irwin, a research scientist who has worked and lived in
Central America much of his life, and who now works at NASA's
Marshall Space Flight Center. 

"It's not just a matter of fencing off animals and keeping it
separate, because there are so many people who live in the region,"
Irwin says. 

Sustainable development is a relatively new direction in
environmental thinking. It acknowledges that people need to use
nature's resources to survive, but it also asserts that people must
do so in an ecologically sensitive way, or else those resources may
not be there for future generations. 

For example, farmers might be encouraged to enrich the nitrogen in
their existing fields by planting legumes such as alfalfa, rather
than cutting and burning more forest when the soil becomes depleted.
Another popular approach is to use tax incentives to motivate a land
owner to set aside some of the forest on their property rather than
developing it. 

To maximize the ecological benefit of saving these forests, the CBM
maintains strips of land connecting the forested areas--another
relatively new idea in wildlife conservation called "corridors." 

Animals and plant seeds can then move between the areas, reducing the
threat of inbreeding or local disasters wiping out a species. And
they provide more space for top carnivores such as jaguars who range
long distances to survive. That's why the network of connected areas
as a whole has more ecological value than the sum of its parts. 

"Because you don't have intense migrations like in the African
savannah, your corridor can serve its purposes and still allow
certain kinds of human uses," explains Archie Carr III, a veteran
conservationist who leads the Wildlife Conservation Society's
projects in the Caribbean. Carr led a project between 1990-95 called
the Paseo Pantera (Spanish for "path of the panther") that originally
established the corridor system that later became the CBM. 

Coffee, for example, had traditionally been grown under the shade of
trees. This kind of coffee field mimics the structure of a natural
forest and thus provides good habitat for wildlife. 

"Some of this shade-grown coffee would provide corridor functions
probably perfectly well for an enormous number of tropical
creatures," Carr says. 

But in modern times, a more productive, sun-tolerant strain of coffee
was introduced to the region, leading to treeless coffee fields with
little habitat for wildlife. Various organizations including the CBM
and the Rainforest Alliance are now trying to persuade coffee farmers
to return to the more ecological, shade-grown system. 

Watching from above

It's not easy for the region's environmental managers to keep an eye
on such a large area of land, though. That's why the
intergovernmental agency in charge of the corridor, called the
Central American Commission for Environment and Development (CCAD),
has recruited the bird's-eye view of NASA satellites to help out. 

"The landscape-wide perspective that satellites provide is essential
for doing a large-scale conservation project like this," Irwin says.

"The rain forest is so thick in many places that you can hardly see
10 feet in front of your face," Irwin says. "Trying to survey such
large areas on foot is nearly impossible." 

To get the job done, Irwin and his colleagues use data from an
assortment of satellites. For assessments on the scale of entire
countries, they use data from the Moderate-resolution Imaging
Spectrometer (MODIS) on NASA's Terra and Aqua satellites. This sensor
takes images whose pixels each cover 250 meters of ground, suitable
for looking at such large scales. Landsat, on the other hand, has a
resolution of 30 meters, and is more useful for closer looks. 

NASA signed an agreement with CCAD in 1998 to use its Earth-watching
satellites--called the Earth Observing System--to help the corridor
project. One outcome of this collaboration was a study using Landsat
data from the 1990s that showed that the corridor was indeed
protecting the forests. About 80% of forests inside the CBM still
remained, compared with only about 31% outside the corridor. And
annual forest clearing rates were 5.5 times higher outside the
corridor than inside (1.44% versus 0.26%). 

With help from the World Bank, the team also assembled an ecosystem
map for all of Mesoamerica. The first of its kind to cover the entire
region, this map shows in detail where the rain forests, lowlands,
and croplands all lie--an invaluable tool for those managing the CBM.

These managers use the satellite data in other ways as well. For
example, data from MODIS shows the location of burning fires in the
entire region in near real-time (as in the image at the top of this
article). 

So far, however, the principal use of the satellite data has been as
a political tool, according to Jorge Cabrera, the CCAD official in
Central America handling the collaboration with NASA. 

"In the case of the fires in the Petén and Yucatan regions this year,
giving this information to the media succeeded in mobilizing more
political, institutional, and public interest in the magnitude of the
disaster," Cabrera said in an e-mail interview (translated from
Spanish). 

 - Continued -

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