The destination of arable land in a marginal agricultural landscape in South Portugal: an exploration of land use change determinants

This research attempts to investigate what drives three conversions of arable land during the period 1985-2000 in a marginal agricultural landscape in Southern Portugal: afforestation of arable land, abandonment of arable land and regeneration of the agro-silvo-pastoral system. This was done by exploring the associations between these changes and a selection of both biophysical and socio-economic variables in a study area of 44 square km. For each conversion of arable land into one of the three other land use types the descriptive power of the various independent variables were evaluated using logistic regression. By comparing different statistical models (one containing only the biophysical attributes, another model containing only the socio-economic variables and finally a model containing both types of variables) the relative importance of socio-economic and biophysical variables was evaluated. The results show that both the biophysical and socio-economic variables were significantly associated with the occurrences of the land use changes. However, the models containing only the socio-economic variables were stronger related to occurrences of afforestation and regeneration of the montado, whereas the biophysical variables were more related to land abandonment. The landowner type was a significant descriptive variable across all land use change models. The results suggest that local socio-economic factors are significant in explaining the pattern of the conversion of arable land in the study area and for this reason the variety of landowners' response to the physical conditions deserves more attention in land use change modelling.