FOREST CHANGE ESTIMATES FOR THE NORTHERN PETEN REGION OF GUATEMALA - 1986-1990

Landsat-thematic mapper images recorded April 1986 and 1990 were obtai ned for northern Guatemala. The study area corresponds to a major port ion of Guatemala's Maya Biosphere reserve but also includes land outsi de the western and southern boundary of the reserve. The normalized di fference vegetation index (NDVI) was computed at each date and image d ifferencing (subtraction) was performed. The resulting image was thres holded into three categories: regrowth, no change, and forest clearing . A 10 x 10 km grid system was superimposed on the image to categorize the percentage of each 100 km2 cell that changed between 1986 and 199 0. Forest clearing patterns were apparent along the border areas (Mexi co and Guatemala) and all along the southern portion of the study area where human populations were moving toward the Maya Biosphere borders , along existing roads. Forest clearing was negligible or absent in th e roadless areas.