The patterns and driving forces of forest loss and fragmentation were assessed in four study areas:
two in Mexico (Central Veracruz and the Highlands of Chiapas) and two in Chile (Rio MauleCobquecura
and Los Muermos-Ancud). For the Highlands of Chiapas, Rio Maule-Cobquecura
and Los Muermos-Ancud study areas, three land-cover maps were derived from satellite imagery
acquired between 1975–1976 and 1999–2000. For Central Veracruz, two land-cover maps were
obtained from the interpretation of aerial photographs and Landsat ETM+ satellite images for
1984 and 2000, respectively. Analysis of these images indicated a reduction in natural forest area
of 67% in Rio Maule-Cobquecura, 57% in the Highlands of Chiapas, 26% in Central Veracruz and
23% in Los Muermos-Ancud. These losses are equivalent to annual forest loss rates of 4.4%, 3.4%,
2.0% and 1.1% per year, respectively. Forest fragmentation in the study areas led to a decrease in
forest patch size, which was associated with a rapid increase in the density and isolation of forest
patches and a decline in area of interior forests and number of large patches. Logistic regression
models were used in each study area to identify the factors associated with forest loss. Overall, the
probability of an area being cleared of forest was greatest in gently sloping areas and around the
margins of forest patches. Additionally, soil fertility appears to be a significant factor associated
with deforestation in Central Veracruz. In Maule-Cobquecura and Los Muermos-Ancud the probability
of deforestation was higher as size of forest fragments decreased, whereas in the Highlands
of Chiapas large fragments were particularly vulnerable to deforestation. Given the current trends
of forest loss, we predict that further declines and spatial changes of forest cover will occur in each
of the study areas. The patterns observed reveal some of the immediate causes of deforestation in
Mexico and Chile such as pasture and crop expansion, forest logging and conversion to plantations
of exotic tree species. These changes highlight some weaknesses in the national environmental
and economic policies in the countries included in this study.