Hierarchical modeling highlights how ecosystem service provisioning by service crops intercropped with oilseed rape depends on their functional trait values

Abstract

The mix of oilseed rape with service crops is currently considered to be an interesting way to reduce the use of external inputs by supporting the provision of ecosystem services. Our aim was to synthesize knowledge on the services provided by service crops mixed with oilseed rape, in order to inform the choice of service crops using the trait-function-service functional ecology approach. To do so, we built a simulation model of trait-function-service based on expert knowledge and the scientific literature on weed regulation, nitrogen recycling, and pest regulation, as well as the disservice related to competition. We simulated the ecosystem services and the disservice provided by 20 service crops clustered in functional groups. Our results showed that the trait values of height, dead biomass in contact with the soil, growth rate, earliness, leaf area, nitrogen fixing capacity, drought resistance and biomass production potential were the traits that were decisive for the classification of species into functional groups. The services provided differed according to the functional groups and therefore the values of their traits. Hence, some functional groups can provide multiple services while some are single service. We also showed that the level of the disservice increased when the ecosystem services provided increased. The identification of the traits of interest allows us to orient research on the assembly rules of the traits and thus the interspecific mixtures with oilseed rape most likely to provide a given ecosystem service.