Weed seed predation : a promising ecosystem service in agriculture

Sammanfattning: Enhancing biodiversity and promoting vital ecosystem services can reduce the global dependence on anthropogenic inputs in agriculture while securing crop yield. Weed infestation can severely reduce crop yield but the dominance of herbicides for weed control can impair human health, beneficial organisms and ecosystem service delivery. Thus, it is essential to identify more sustainable alternatives for weed control. Using data from four European countries, this thesis examined whether the ecosystem service of weed seed predation in cereal fields can be a viable alternative for regulation of weeds. The impact of agricultural intensity on weed seed predation, weed regulation and functional redundancy in predation was investigated, as well as the role of seed and alternative prey availability. The results showed that through weed seed predation, regulation of weeds at population and community level is achievable. Weed seed availability increased predators’ potential for weed seed predation, but higher alternative prey biomass reduced seed consumption. Functional diversity in predation increased the spatial stability of weed seed predation. Agricultural intensity decreased weed seed predation and functional redundancy in predation estimates, via increased disturbances at field level, reduced diversity of crops sown in rotation and reduced landscape heterogeneity. These findings confirm the potential of weed seed predation for sustainable weed control and suggest that to support weed seed predators and the service they provide we need to reduce field management intensity and diversify cropping systems at both field and landscape scale.