The potential of ecological transition to provide environmental services in peri-urban subtropical forests of NW Argentina

HERNANDEZ, ME; GRAU, HR; GUTIERREZ, J; CASAVECCIA, C; FLORES, E

Beijing, China

Congreso; Global Environmental Change:Regional Challenges; 2006

We analyzed changes in land-use during the last 30 years in the Sierra de San Javier, a 20,000 Ha mountain range covered by subtropical forests located nearby the city of San Miguel de Tucuman (800.000 inhabitants), in relation to the provision of the ecological service of watershed protection. Land use changes were evaluated by comparing areal photographs and satelites images in two dates: 1968 and 2001, and used, along with climatic, soil and topography maps to calculate soil erosion and sediment yield by the Gavrilovic method modified for a GIS environment. Forest area increased since 1968. The new forests are mostly located in areas of steep slopes, and are largely dominated by exotic tree species. The area of urban development and intensive agriculture also increased, and the areas of pastures decreased. New forests had a positive effect on watershed protection, since the new forests are located in steep areas with larger per-area impact on soil erosion.Overall, the process of forest recovery associated to urban expansion seems to improve the environmental service in the area, although some emerging environmental threats need to be evaluated, including the role of exotic species and the impact of low-density urbanization on land cover.