Ecology Ablaze

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.

In an area of rich bio diversity, 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.

"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.

Image courtesy CBM.

This map of the Mesoamerican Biological Corridor shows the same region pictured in the satellite photo above. Dark green denotes protected areas; light green denotes connecting corridors. Red areas are proposed protected areas

"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.

Photo courtesy CBM.

People and wildlife often live in close proximity in Central America, and their needs sometimes conflict.

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.

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).

This photo was taken in Petén, Guatemala, by Daniel Irwin.

Slash-and-burn agriculture destroys forests and wildlife.

In December, NASA signed a new agreement with the CCAD and the World Bank to continue the use of satellites for the corridor project, and to look into an innovative new way of making the satellite data available.

The concept they're considering is a live "dashboard" showing the state of the environment in Central America as seen by NASA satellites in near real-time, just as the dials on a car dashboard show the state of the car. A computing "pipeline" would be designed that would automatically gather the latest data from the satellites, process the raw data into a relevant and useful form, and present this user-friendly information to the people who need it: Central American politicians, civic leaders, and even local students.

"The information would be available in a timely manner for the Central American decision makers - the ministers, the people who are really making the calls about the environment down there," Irwin says.