RATES OF DEFORESTATION IN THE HUMID TROPICS - ESTIMATES AND MEASUREMENTS

There is still great uncertainty attached to estimates of deforestation rates for tropical moist forest. The estimates, which varied from 11 to 15 million hectares for the early 1970s to 6.1 to 7.5 million hectares for the late 1970s and 12.2 to 14.2 million hectares for the 1980s, are evaluated using an original set of criteria and the uncertainty is shown to result from lack of attention to remote sensing measurements and overconfidence in the use of expert judgement. Estimates of the total area of tropical moist forest are also unreliable, despite the increased use of remote sensing data in their derivation. A continuous satellite-based global monitoring system is needed to obtain better estimates and the institutional requirements for this are discussed.