ABSTRACT
Climate change and land use change are predicted to be the two main drivers of global biodiversity alterations (Sala et al. 2000). The effects of climate change on biodiversity are manifested at different scales, from genes (i.e. generating mutations and simplifying gene pools) to species (i.e. extinctions and range modifications) and ecosystems (i.e. community composition and distribution changes). These effects influence ecosystem functions and processes, for instance changes in the abundance and composition of plant species may influence water cycle, nutrient and carbon dynamics, trophic interactions and disturbance regimes (Chapin III et al. 1997; Diaz et al. 2004). Ecosystem functions are linked to the provision of ecosystem goods and services
when human values are considered (de Groot et al. 2002; MEA 2005). Many authors have highlighted the value of these ecosystem services for sustainable development, globally (Costanza et al. 1997) or locally (Lutz et al. 2000; Woodward and Wui 2001; Pattanayak 2004). Terrestrial ecosystems provide an array of watershed services, for instance the regulation of hydrological flows, benefiting agriculture, drinking water users, energy production, or transportation (Costanza et al. 1997; MEA 2005). Watershed services are of outmost importance in many developing countries
where water is a crucial development issue, such as Central America (Locatelli et al. 2010). According to UNDP (2006), around 20 per cent of global population lives without access to potable water. Nicaragua being the second poorest country in Latin America provides a good example, where only 49 per cent of the rural population has access to this resource and high water-related mortality is observed (CONAPAS 2006). Potential conflicts in the future could be expected due to freshwater use and access, given pressures from population growth and water use demand (i.e. for irrigation and industry; UNFPA 2006). The degradation of ecosystems and the associated loss in the provision of
ecosystem services are major threats for human well-being (MEA 2005). Knowing
about the impacts of climate change on the ecosystems hydrological functions is necessary to inform policy makers about the risks induced by climate change and support their decisions about adaptation to future changes (Scholze et al. 2006). In this chapter we aim at assessing changes in ecosystem hydrological services
under future climate scenarios and impacts on per-capita water availability for main watersheds of Mesoamerica. We used several climate change scenarios and a biogeography model to project a range of potential changes in the provision of ecosystem services while accounting for uncertainty from climate models and future emission scenarios. These results could be used as the basis to assess the vulnerability to climate change, at the national and regional scale, of important economic sectors relying on hydrological services (i.e. agriculture, power generation, drinking water).
Previous studies in Central America
