Validation of European ecosystem service maps
Over the past decades, ecosystem services have emerged as a way to understand landscape dynamics and their consequences for human well-being. The concept of ecosystem services has been taken up by both the scientific community and in policy making. For example, a wide range of methods for mapping ecosystem services has been developed and recently, the Biodiversity Strategy of the European Union addressed the protection and enhancement of ecosystem services as a specific target.
A major challenge in ecosystem service mapping and modelling is the limited knowledge on the validity of the results. Methods for mapping ecosystem services range from empirical models aiming to assess large sets of services and support decision-making, to complex models that aim to understand and describe specific ecological processes that control the provision of the ecosystem services. Such different mapping approaches proved to lead to different outputs, influenced by among others input data, definitions and model formulation. However, as ecosystem service maps are hardly validated and attention for model sensitivity and uncertainty in model outcomes is limited, the trade-off between model complexity and accuracy of the outcomes is mostly unknown. Consequently also the choice for a certain method for ecosystem services mapping is not well founded.
To increase insight in the validity and uncertainties of different mapping approaches for ecosystem services, we perform a study on the quality of ecosystem service maps. We analyze a varied set of provisioning, regulating and cultural services. For each service, we selected existing European-scale maps based on methods ranging from simple empirical approaches to more complex methods. We make a comparison of the main patterns of these maps, assess the sources of uncertainties and differences between the maps, and perform a validation.
Based on these results we provide insight in the accuracy of different methods for mapping ecosystem services. Finally, we provide guidance on the optimal methodology for ecosystem quantification for policy support.