Plant strategies as biological indicators of ecosystem services

Ecosystems provide services that are essential to human welfare and have been broadly classified into four types: 1). provisioning (the supply of ecosystem products including affecting food, fuel and water), 2). supporting (such as nutrient cycles and primary production that allow other ecosystem services to proceed); 3). regulating (controlling the extent of environmental processes, including climate), and 4). cultural (spiritual, recreational and scientific benefits). Ecosystem services are typically assessed using economic indicators such as perceived dollar value, but despite the importance of ecosystem properties and processes in governing ecosystem services the biotic characteristics of ecosystems do not currently play a central role ecosystem service assessment. Plants are the primary producers in terrestrial ecosystems and account for the majority of the biomass, and so the main aim of the present study was to develop a method whereby plant ecological strategies can be used to quantify and compare the four main types of ecosystem service. Sixty herbaceous plant communities, representative of a wide ecological range within the Alps and central Europe, were used to quantify differences in community-weighted mean (CWM) functional trait values, above and below ground biomass, and the quality of the species present (i.e. invasive, rare). Provisioning services were estimated as a function of the CWM values of above-ground biomass, canopy height and leaf dry weight. Supporting services were estimated as a function of leaf nitrogen content and local seasonality (flowering start and flowering period). Regulating services were calculated from the amount of sequestration in the form of below-ground dry weight and leaf carbon content. Cultural services were calculated from the relationship between the presence of protected species, black list species and the proportion of plant species in flower. Values for each ecosystem service type were compared with the CWM values of Grime’s CSR plant strategies calculated from leaf economics and size traits. Grime’s competitor strategy was found to be highly representative (i.e. correlated with) the degree of provisioning. The extent of ruderalism in the plant community was found to indicate the extent of supporting services, and the degree of stress-tolerance in the plant community was found to denote regulating services. Cultural services were not related to the plant strategies present. These findings underline the utility of plant CSR strategies as readily-applicable indicators of ecosystem services, at least for those that involve resource stocks and cycling, but not for cultural services.