Probing tropical deforestation: the use of GIS and statistical analysis of georeferenced data

The significance and magnitude of the relationship between forest cover and ten environmental variables were investigated in a case study of Mindoro, Philippines. Landsat Thematic Mapper data and thematic maps were processed for Pearson's chi-square test, Cramer's V calculations and logistic regression analysis. Attribute query and display of composite layers in GIS were further implemented to analyse the deforested lands. These statistical analyses show that some variables are significantly related to forest cover, although the magnitude of relationship for all variables is weak. In contrast with most studies, the accessibility and topographic factors in this study, among others, are not significantly associated with forest cover. Associations between forest cover and some topographic and edaphic factors support the hypothesis that the area's many deforested lands are actually 'natural grasslands'. However, external evidence suggests that burning forests for grazing purposes at least maintains and probably expands the area's deforestation. Because of the high spatial, temporal and attribute variability of deforestation, extrapolation and generalization from the results should be made with caution, especially if they will be used as inputs for planning and management.