Quantifying and mapping multiple ecosystem services change in West Africa

Although ecosystem services have been identified to be declining over the previous decades, there is no clear methodology of evaluating the impacts of land use change on ecosystem services. This paper presents a methodology for quantifying and assessing changes in multiple ecosystems services as a result of land use change using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. The model was used to map and quantify biodiversity and four ecosystem services for Ghana and Cote d’Ivoire for 2000, 2005 and 2009 land use conditions: water yield, carbon storage, nutrient retention, and sediment retention. The study developed a suite of indices to analyze land use change impacts on the status, change and spatial patterns of multiple ecosystem services. On a national scale, the results show a mix of increases in service (water yield, N retention and P retention in Ghana, and, N and P retention in Cote d’Ivoire), little change in services (sediment retention in Ghana and sediment retention and water yield in Cote d’Ivoire) and decreases in services (biodiversity and carbon storage in both countries) from 2000 to 2009. The assessment illustrates a methodology that can be employed by land managers in exploring multiple management scenarios and their implications for multiple ecosystem services change.

► Indices were developed to analyze land use change impacts on ecosystem services.
► Results show a mix of increases, little change and decreases in services over time.
► Water quality provisioning decreased in the cropland and agroforest land use areas.
► Forests, and agroforest land uses are critical for ecosystem service provisioning.