Engineering a plant community to deliver multiple ecosystem services

The sustainable delivery of multiple ecosystem services requires the management of functionally diverse biological communities. In an agricultural context, where conflicting services often need to be reconciled on the same parcel of land, growing species mixtures may improve multi-functionality when compared to monocultures. In this case, the optimum number and identity of species will be determined by trade-offs between ecosystem services, functional composition of the available species pool and competitive dynamics. A combination of functional trait / ecosystem service relationships and a process-based model of plant competition was used to engineer a plant community that delivered the optimal balance of services using the case study of a legume-based fertility building cover crop. An experimental species pool of 12 cultivated legume species was screened for a range of functional traits and ecosystem services at five sites across a geographical gradient in the UK. All possible species combinations were then analysed to identify the community that delivered the best balance of services at each site. In our system, low to intermediate levels of species richness (1-4 species) that exploited functional contrasts in growth habit and phenology, were identified as being optimal. The optimal solution was determined largely by the number of species and functional diversity represented by the starting species pool emphasising the importance of the initial selection of species for the screening experiments. The approach of applying functional traits / ecosystem service relationships to the design of multi-functional biological communities has the potential to inform the design of agricultural systems that better balance agronomic and environmental services and meet the current objective of European agricultural policy, to maintain viable food production in the context of the sustainable management of natural resources.