Biology Professor Evaluates Deforestation and Species Richness Using Satellite Imagery

By Peter Grennen

In biology professor Kamaljit Bawa's area of research, it is sometimes difficult to see the forest for the trees"literally. Bawa studies the causes and consequences of deforestation and other forms of environmental degradation in the tropics, attempting to assess the extent to which plant species are being lost there. His aim is to gather data that can be used to improve conservation policies and develop alternative uses for land.

This work is part of a multidisciplinary, multi-investigator effort to promote biodiversity through sustainable use of natural resources in the forests of Central America and the Indian subcontinent. And the stakes couldn't be higher"it is research in the very viability of the planet. "One out of every eight plant species is threatened with extinction," Bawa points out. "Forests are disappearing at an unprecedented pace, soil erosion is assuming massive proportions, and greenhouse gases are altering the climate."

These trends all point to a serious decline in the earth's health over time and an ever-more-urgent need to preserve forests. They also underscore a lack of information in several key areas that has hindered attempts to combat forest degradation. "Rapid assessment of biodiversity is critical for conservation planning, but there are few methods that can be used in large areas without intensive, time-consuming ground surveys," says Bawa. "To identify areas of high species richness, remotely sensed imagery over large landscapes is needed."

Responding to that need, Bawa has begun doing remote sensing of forests from one of the most remote locations imaginable"many miles above the earth's surface. He uses satellite imagery to delineate areas of high and low species richness in the Biligiri Rangaswamy hills of Western Ghats, India. The images he has collected offer evidence of a positive correlation between known indicators of species richness and the Normalized Difference Vegetation Index (NDVI), which is a measure of an area's green biomass as seen from space.

That result is not altogether surprising, because there is a well-established relationship between the NDVI and the biological productivity of an ecosystem, itself a measure of an area's free energy. The real genius of Bawa's project is that it uses existing technology in a new way. "Remote-sensing imagery has greatly enhanced our ability to monitor biodiversity losses at the landscape level," he says, "but it has not yet been used to identify species richness."
So this study boldly goes where no other has gone"and consequently it is getting some well-deserved recognition. It has won financial backing from a number of public and private organizations, including the U.S. National Science Foundation, the Ford Foundation, and the Alcoa Foundation. Bawa himself was recently appointed to the U.S. National Committee of the International Union of Biological Sciences, which coordinates a range of biology-related activities around the globe.

Bawa's work with satellite images was highlighted in the "Editor's Choice" section of the January 17, 2003, issue of Science, the premier science publication in the United States and one of the most prestigious in the world. The journal noted: "This technique shows promise for estimating broad patterns of tree species diversity at the landscape scale in tropical forests, which may be crucial to identifying areas most in need of protection and where rapid destruction is under way."

Professor Bawa shares this optimism, but he is quick to mention the limitations of his approach. "Satellite imagery must be followed by detailed work on the ground to confirm the trends and to precisely document the biodiversity," he says.

It's an object lesson in the methodology of science: Although viewing from a great distance can provide much-needed perspective, there is no substitute for the up-close observations of scientists whose feet are planted on terra firma.

Image: Professor Kamaljit Bawa of the Biology Department, shown here in UMass Boston's Greenhouse, was honored for his work in deforestation studies by the journal Science. (Photo by Harry Brett)

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