The researchers interviewed 1,393 wood-mill operators and 202 landholders and checked the effect of fires from an airplane at 1,104 sample points. Although they acknowledge the importance of satellite-based monitoring, the researchers say the only reliable way to find out what is happening is by field surveys. But this monitoring needs to be expanded to include forests affected by logging and surface fire if it is to accurately reflect the full magnitude of human influences on tropical forests. The findings trouble scientists because perhaps a third of the world's plant and animal species live in the rainforest. The researchers also worry about huge quantities of carbon dioxide entering the atmosphere from the fires.
Carbon dioxide is thought to cause global warming.
In addition, some scientists fear that damage to the rainforest, which gives off enormous amounts of water vapor and keeps the ground from drying out, could throw the earth's climate out of balance. The researchers called for more judicious timber harvesting, more prevention of accidental fires, and curbs on roads, power grids, and water systems. However, some experts are doubtful about the prospects of controlling development in the rainforest, where the law of the jungle often prevails. The findings were published in a recent issue of the journal Nature . For related stories, search our Archive.