The impact of two decades of land-use changes in potential ecosystem services supply in a Portuguese municipality - Coimbra

Land-use changes affect the properties of ecosystems, and are typically associated with decreasing ability to supply services, which in turn causes a decrease in the social well-being. Urbanization is identified as one of the main causes of ecosystem degradation, once it is considered an artificial space that replaces natural areas.This study investigates the impact of land-use changes during 20 years (1995-2015) on the potential supply of ecosystem services in Coimbra municipality, central Portugal. The assessment was based on the evaluation performed by 31 experts familiar with the study area, through questionnaires. The experts ranked the potential supply of 31 ecosystem services, grouped in regulation, provisioning and cultural services, for the several land-uses existent. Experts performed a qualitative evaluation, considering ‘strong adverse potential’, ‘weak adverse potential’, ‘not relevant’, ‘low positive potential’ and ‘strong positive potential’. The qualitative evaluation was converted into a quantitative classification (-2, -1, 0, 1, 2). Quantitative values were then used to develop an ecosystem services quantification matrix and to map the information in the study area, using Geographic Information Systems (GIS). An urban expansion from 14% to 18% was recorded over the last 20 years. Agricultural land decreased 8% due to conversion into forest (4% increase) and urban areas (4% increase). This has led to a decrease in the supply of provision (e.g. food) and regulation services (e.g. flood regulation). In fact, over the last years, recurrent floods have been increasingly noticed in Coimbra city. On the other hand, the growth of forest areas has led to an increase in general ESs supply. The adverse impacts of urbanization were partially compensated by enlarging the benefits provided by forest areas, which is the land-use with greatest ESs potential supply. In order to support urban planning and develop sustainable cities, it is essential to quantify the potential supply of ecosystem services considering local scale and characteristics.