Speaker
Description
Introduction
Given the backdrop of global climate change, the biodiversity crisis and the energy transition, agriculture must transition from intensive to multifunctional management (Wittwer et al., 2021). Multifunctionality refers to the ability of ecosystems to simultaneously perform multiple functions, thus ensuring the delivery of diverse ecosystem services important for human well-being (Stürck and Verburg, 2017). Agroecosystem multifunctionality studies comparing organic and conventional systems yielded controversial results that could be explained by differences in management practices. Indeed, current knowledge is particularly limited regarding how cropping systems and individual management practices might modulate agroecosystem multifunctionality (Wittwer et al., 2021). This study analyzed how management practices affect agroecosystem multifunctionality and, trade-offs and synergies among underlying functions. We considered three management practice description levels: (i) farming system (i.e. organic vs. conventional), (ii) combination of management practices that defines a cropping system, and (iii) individual management practices.
Material and methods
We measured 14 primary variables, used as proxies for seven functions, in 20 conventional and 20 organic winter cereal fields in Brittany, northwestern France. We evaluated biodiversity conservation by considering species richness of carabids, flower-visiting insects and weeds. Predation was quantified by measuring the abundance of pest natural enemies including carabids, spiders, staphylinids, ladybird larvae, and aphidophagous hoverflies. Pest colonization consisted of the abundance of two main pests of cereal fields: aphids and troublesome weeds. Pollination was estimated through the abundance of flower-visiting insects. Food and feed production was quantified using yield (quantity of products per hectare). Quality of life at work was based on the number of working hours in the field. Lastly, income contribution was assessed using costs (labor according to materials used and inputs) and sales of crop production. Generalized Linear Mixed effect Models (GLMMs) were built to assess the effects of management practices on multifunctionality index and each function. Trade-offs and synergies between functions were assessed through Pearson correlations.
Results
Multifunctionality did not differ between organic and conventional systems. We found a strong trade-off between functions related to ecological performance and socio-economic performance, especially between biodiversity conservation and food and feed production. Organic systems tended to minimize this trade-off. Our study also revealed great variability in multifunctionality among cropping systems (N = 5) and within each cropping system type. The number of soil interventions and nutrient inputs were the main drivers of agroecosystem multifunctionality and its underlying functions.
Discussion
Although organic management did not increase multifunctionality, it was beneficial to biodiversity-based functions, likely due to the absence of applied chemical products. Some cropping systems had similar multifunctionality index value but none maximized both food and feed production and biodiversity-based functions. This suggests that multifunctionality may be achievable via different management paths, allowing farmers to choose the strategies most adapted to the particular objectives and constraints of their farm (e.g. pedoclimatic conditions, farm machinery, workload). Exploring the effects of individual management practices, we found that the number of field interventions and the fertilization amount are the main determinants of cropping system performance. Logically, fields that require numerous interventions to limit the proliferation of weeds, through mechanical weeding or more frequent application of herbicides, are also those placing greater labor costs on farmers.
We thus demonstrated that beyond the organic vs. conventional system dichotomy, combinations of management practices (i.e. cropping systems) as well as individual management practices can explain the ecological and socio-economic performance of agroecosystems. In addition, we showed that specific management practices, such as reducing within-field interventions and fertilization amount, could be integrated even in conventional cropping systems to improve agroecosystem multifunctionality.
References
Gong, S., et al. (2022). Biodiversity and yield trade‐offs for organic farming. Ecology letters, 25(7), 1699-1710. https://doi.org/10.1111/ele.14017
Stürck, J., & Verburg, P. H. (2017). Multifunctionality at what scale? A landscape multifunctionality assessment for the European Union under conditions of land use change. Landscape Ecology, 32, 481–500. https://doi.org/10.1007/s10980-016-0459-6
Wittwer, R. A., et al. (2021). Organic and conservation agriculture promote ecosystem multifunctionality. Science Advances, 7(34), eabg6995. https://doi.org/10.1126/sciadv.abg6995
| Keywords | Cropping system; ecological performance; socio-economic performance; biodiversity conservation; trade-off |
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