Assessment of swaps and persistence in land cover changes in a subtropical periurban region, NW Argentina

A detailed spatial analysis of land cover changes was carried out in the periurban area of Great San Miguel de Tucumán and Sierra de San Javier, subtropical Argentina. Post-classification comparison of land cover maps of 1972 and 2010 was used to quantify the level of persistence, net gains, losses and swaps among urban, natural vegetation, and agriculture categories; framed in a hierarchical land use/cover classification. The spatial distribution of land cover changes was related to environmental and socio-economic variables. The overall land cover change pattern of “periurban forest transition” was characterized by urban expansion, agriculture adjustment and associated forest recovery. Montane forests showed a net increase of 10%, expanding over mountain grasslands, which in turn lost 66% of their original area. Dry forests experienced high levels of swaps, being relocated into more humid areas and further away from access roads. Simultaneously, herbaceous agriculture was concentrated in flat areas more suitable for modern mechanized agriculture. In the foothills of the San Javier range, urban areas tripled their original extension replacing fertile agricultural lands (mainly sugar cane). Forest recovery and land-use intensification patterns are usually considered as an opportunity for conservation of biodiversity and ecosystem services. However, these new forests are characterized by the abundance of exotic species with little known ecological properties. Also, the replacement of highly productive agriculture by urban developments, and of natural montane grasslands by forests, imply negative changes in terms of agriculture production, the conservation of grassland biodiversity and landscape configuration with high recreational value.