The critical role of abiotic factors and human activities in the supply of ecosystem services in the ES matrix

In Western Europe, ecosystems have been shaped to maximise the supply of one specific biomass provisioning ecosystem service (ES), such as food or timber, with detrimental impacts on other ES. The ES approach has therefore been established to better understand the multiple interactions between human society and ecosystems. A variety of methods have been developed to assess ES and their relationships, for instance the ES matrix model based on land cover classes. This popular, flexible and simple method allows combining different data sources and easily comparing ES. However, in general, this method poorly takes into account landscape heterogeneity while abiotic factors and human activities seem to play an important role in ES supply. The objective of this paper is twofold: (1) to extent the methodology based on the ES matrix model by including abiotic factors and human activities and (2) to test the impacts of these two types of factors on ES supply and their relationships. The assessment focused on the capacity of the forest to supply six ES depending on six types of soil ranging from productive soils to more constraining or less productive soils (i.e. abiotic factors) and two contrasting forest management strategies (i.e. human activities). This amended ES matrix was applied on one hand, to map the supply of ES and their relationships in four municipalities in the Ardenne ecoregion (Southern Belgium) and on the other hand, to investigate the impacts of three scenarios (i.e. three different management strategies) on ES supply and their relationships. The amended ES matrix shows large differences in ES supply between the two forest management strategies on the more constraining and less productive soils, creating differences in the spatial pattern of ES. The changes in ES supply amongst the three scenarios and the current supply were quantified to identify the best management options. In conclusion, one particular forest is not like another in terms of ES supply and their relationships. To capture this heterogeneity, we propose an amended ES matrix including abiotic factors and human activities. The maps, based on this matrix, allow identifying the hotspots (i.e. high capacity to supply different ES) and coldspots (i.e. low capacity to supply different ES or strong trade-offs between provisioning ES and regulating/cultural ES). Forest management should be adapted to the abiotic conditions, in particular in the coldspots, to ensure a more balanced supply of ES.