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.