Productive specialization explains 40 per cent of
the total variance of residuals obtained from the environmental model developed with 24 land-cover
classes, while the other variables show weak
correlations and low levels of statistical significance
(Table 4). Positive values of productive specialization
factor in areas traditionally devoted to forestry and
grazing are related to positive residuals, while
negative values for areas devoted to cropping in
lowland areas are related to negative residuals
(Figures 4 and 5). Only productive specialization
showed statistical significance when regressed
against residuals of the second natural sub-model
with 220 land-cover classes (Table 4).