Biophysical valuation of ecosystem services in the VOTES project: use of a dynamic vegetation model

The VOTES project (Valuation Of Terrestrial Ecosystem Services in a multifunctional peri-urban space) aims to develop a framework to evaluate ecosystem services from a social, economic and environmental point of view, where local stakeholders and end-users have a central role in the valuation process, as they are the direct beneficiaries of the provision of services. Within this project, the framework is applied to a case study in central Belgium, known for its strong peri-urban character, due to the proximity to Brussels. To the end, this quantitative tool designed for a sustainable landscape management is also designed for the evaluation and the monitoring of ecosystem services for policy makers.
The originality is that this framework will provide an integrated valuation of ecosystem services in a spatially and temporally explicit way, based on different steps in which we find biophysical valuation and landscape modelling: the valuation of the biophysical environment is an essential component of the VOTES framework.
To carry through this biophysical valuation, we use the CARAIB model (CARbon Assimilation In the Biosphere), a dynamic vegetation model (DVM) adapted for the valuation of the ecosystem services. This model is combined with another spatial model, an agent-based model (ABM), used to project land use change into the future. Initially, CARAIB was designed to describe (non-managed) natural ecosystems dynamics over large spatial domains and at coarse resolution. In consequence, the model had to be adapted to the VOTES smaller scale case study (including a higher resolution) but, mainly, the model had to be modified to quantify key ecosystem services, e.g., through the addition of a module dedicated to (manage) crops. This new version of the model thus provides direct outputs on the biophysical values of ecosystem services, e.g., productivity (food/fodder, wood production, etc) or carbon storage, which leads to a mapping of these ecosystem services not only for the present, but also for the future until 2050. Indeed, the coupled DVM-ABM is used to construct future (dynamic) scenarios that include the major driving forces of the system (e.g., global socio-economic context, climate change, urbanization pressure, etc) together with adapted management. The computed scenarios will provide the changes in the biophysical system consistent with the socio-economic evolution, including changes in ecosystem structure and function. This will allow an estimate of a change in the provision of ecosystem service through time, so that the sustainability of ecosystem services under the studied scenarios can be assessed.