Brian Dunbar June 24, 1993 Headquarters, Washington, D.C. (Phone: 202/358-1547) Allen Kenitzer Goddard Space Flight Center, Greenbelt, Md. (Phone: 301/286-8955) RELEASE: 93-119 NASA STUDY REFINES ESTIMATES OF AMAZON DEFORESTATION Tropical deforestation and adverse effects on tropical forest habitat have increased in the Brazilian Amazon Basin since the late 1970s, a University of New Hampshire-NASA study has revealed. Data from the Landsat-4 and -5 satellites covering 1978-88 indicate that although the extent of deforestation is less than expected, deforestation has increased substantially and created adverse "edge effects" that pose a substantial threat to the habitat of plant and animal species. The study indicates that between 1978 and 1988, the rate of deforestation in the Brazilian Amazon Basin was 6,000 square miles (15,000 square kilometers) per year. Results of the study, conducted at NASA's Goddard Space Flight Center, Greenbelt, Md., and the University of New Hampshire, Durham, will be published in the June 25 issue of Science magazine. "We are seeing less deforestation than had been expected," said David Skole, Ph.D., a research assistant professor with the Institute for the Study of Earth, Oceans and Space at the University of New Hampshire. Dr. Skole is the lead author of the Science paper. "Our study helps clarify actual greenhouse gas emissions, such as carbon dioxide, resulting from tropical deforestation." "Although we found lower deforestation than previously estimated, the effect upon biological diversity is greater," said Compton Tucker, Ph.D., a research scientist in the Laboratory for Terrestrial Physics at the Goddard Center. Dr. Tucker was co-author on the paper. Skole and Tucker studied more than 200 Landsat satellite images, covering the entire forested portion of the Brazilian Amazon Basin. Using Landsat images and a computerized geographic information system, they made specific measurements of deforestation, fragmented forest and edge effects. A fragmented forest is forest surrounded by deforested area. "Edge effects" are the destruction or degradation of natural habitat that occur on the fringes of fragmented forests. These effects include greater exposure to wind, weather, foraging livestock, other non-forest animals and humans. Tropical deforestation increases atmospheric carbon dioxide and has profound implications for biological diversity through destruction of habitat. The conversion of forests to cropland and pasture increases atmospheric carbon dioxide because the carbon content of the forests is higher than that of the agricultural crops that replace them. Carbon dioxide and several other gases in the atmosphere trap heat radiating from the Earth's surface toward space. In doing so, they act similarly to the glass in a greenhouse, which also traps heat, creating the "greenhouse effect." NASA funded the research as part of its Mission to Planet Earth, a long-term program that is studying how the global environment is changing. Using the unique perspective available from space, NASA is observing large-scale environmental processes, such as the role of forests in climate change. The goal of Mission to Planet Earth is to allow humans to better understand natural environmental changes and to distinguish natural changes from human-induced changes, such as deforestation caused by expanding agriculture. Mission to Planet Earth data, which NASA will distribute to researchers worldwide, is essential to humans making informed decisions about protecting their environment. The GSFC-University of New Hampshire study typifies NASA's efforts to work with researchers outside the agency to reduce uncertainty about important environmental issues. These ground-based analyses of satellite data will help quantify environmental changes and clarify the interaction of large environmental systems, such as the tropical forest and climate. While occupying less than 7 percent of the Earth's surface, tropical forests are home to more than half of all plant and animal species. Deforestation is leading to massive extinction of species, including - for the first time - large numbers of vascular plant species, such as trees. "The primary cause of Brazilian deforestation in the last two decades can be attributed primarily to agricultural expansion," Tucker said. The Brazilian Amazon is the largest contiguous tropical forest region in the world. Worldwide estimates of tropical deforestation range from 27,000 square miles (69,000 square kilometers) per year in 1980 to 64,000 square miles (165,000 square kilometers) in the late 1980s. The Amazon Basin of Brazil includes all or part of 8 Brazilian states, covering 2 million square miles (5 million square kilometers). In that region, 1.6 million square miles (4 million square kilometers) are forested, 330,000 square miles (850,000 square kilometers) are tropical savanna and 35,000 square miles (90,000 square kilometers) are water. By using satellite data and the geographic information system, scientists can explicitly map, or stratify, different categories of the Earth's geographic features, such as forests and grasslands, providing a means to compare deforestation results from other studies. As the second generation of American remote sensing satellites, Landsat-4 was launched July 16, 1982 and Landsat-5 was launched on March 1, 1984; both from Vandenberg Air Force Base, Calif., on Delta rockets.