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International audience; Context Managing land use to promote an ecosystem service (ES) without reducing others is challenging. The spatial scale at which no-loss constraints are imposed is relevant.Objectives We examined the influence of the spatial scale of no-loss constraints on ESs when one ES was optimised. Specifically, we investigated how carbon sequestration could be maximized at different spatial scales in France with constraints of no-loss on other ESs.Methods We used a statistical model linking land use and land cover variables to ESs [carbon sequestration (CS), crop production (CP), livestock production, timber growth] in French small agricultural regions (SARs). We optimised CS at the country scale posing no-loss constraints on other ESs at increasing spatial scales, i.e., SARs (scenario 'SARs'), department ('DEP'), administrative region ('REG'), and France ("FRANCE"). We analysed differences between optimized and initial configurations.Results Optimized CS at the country scale increased with the spatial scale at which no-loss constraints were posed (similar to+ 0.51% for 'DEP' and similar to+ 2.05% for 'FRANCE'). The variability of ES variation among the SARs similarly increased. This suggested that constraints at larger scales lead to ES segregation. Correlations among ES variations changed with the scenarios (Spearman's rho between CS and CP was - 0.43 for 'DEP' and - 0.70 for 'FRANCE'). This indicated that different land use strategies produce different degrees of enhancement/softening of ES trade-offs/synergies. Conclusions A trade-off was highlighted: larger spatial scales promoted better performance of the target ES but also spatial inequality. We argue that addressing smaller scales will lead to land-sharing solutions that avoid the local environmental impacts of land-sparing strategies.

International audience; Carbon storage (CS) is essential in mitigating atmospheric CO2 levels, but crop production (CP) contributes to food supply. Land management requires understanding the trade-offs between these important, but conflicting, ecosystem services. We studied land use-based strategies to identify the optimal balance between the two, in particular investigating the role of agricultural intensification. We calibrated a statistical model that linked land cover, land use, climate, and biophysical variables to CS and CP in France at 10 km by 10 km resolution. We designed four optimization scenarios: maximisation at the country scale of (1) CS; (2) CP; (3) joint optimization of CS and CP; (4) same as (3) but with minimization of total energy input. The mono-objective scenarios, (1) and (2), enhanced one ecosystem service while decreasing the other. In scenario (3), both ecosystem services were increased at the same time (+ 2.1% for CS and + 9.6% for CP) with a land sparing approach (decrease and intensification of annual crops and increased forest). In scenario (4), the minimization of energy input resulted in less of an increased in both ecosystem services compared to scenario (3): + 1% for CS and + 1.5% for CP. This scenario promoted a land sharing strategy with enhancement of heterogeneous agricultural land. The good performance of the land sparing approach comes at the cost of a high energy use; on the contrary, the land sharing approach allows improvements that, although more modest, come with energy input minimization. As a vast body of literature stresses the biodiversity conservation value and the positive social impacts of land sharing approach, we argue that scenario (4) is more sustainable.

The dominant specialised cropping system (SCS) has supported the increasing population in China, although this agricultural production paradigm could lead to environmental problems. The modern integrated crop-livestock system (ICLS) in China, designed as a recycling paradigm, can alleviate the negative environmental impacts of SCS. However, it must be better investigated, especially due to the trade-off between increased production and environmental harm. In this study, we set up a multi-criteria evaluation with eight indicators based on emergy analysis to quantify and compare the performance of ICLS and SCS and to evaluate the performance of the indicators along a gradient when a proportion of chemical nitrogen is substituted with manure fertiliser nitrogen (PCSM). We examined one experimental modern ICLS and an average SCS by conducting a household survey in Shandong province. The results showed that the ICLS puts less pressure on the environment ( E L R = 1.04), has higher emergy sustainability ( E S I = 1.09), and generates higher economic benefits per unit area of land ( L P O = 3789.94 $‧ha−1). However, the productivity of the ICLS is lower ( T r = 1.66E+05 sej‧J−1, E O D = 1.07E+11 J‧ha−1‧yr−1, E Y R = 1.13) than that of the SCS. With an increasing gradient of PCSM, for both systems, the productivity and environmental pressure decreased sharply; this trade-off was less marked for the ICLS. Considering sustainable resource utilisation, environmentally friendly production, and system stability, the ICLS could be an option for Chinese agricultural production in regions with serious issues of manure pollution and cultivated land degradation. However, the ICLS needs to optimise the crop-livestock structure, strengthen scientific management, and improve productivity.

International audience; Contexte Agriculture in Western Europe is predominantly input-intensive (fertilisers, water, fuel, pesticides) and relies on feed imports. As a result, it is dependent on oil, which may start to decline in production in the 2020s, thus exposing the agricultural sector to potential economic stress, including increased input prices and decreased farmer purchase capacities. Therefore, it is necessary to assess the capacity of European farming systems (FS) to maintain production levels despite a decline in oil production (i.e., robustness). OBJECTIVE: We aimed to model and compare the time variations in the animal- and crop-sourced production of three French FS under three scenarios of decreased availability of feed and synthetic fertiliser imports. METHODS: We developed a FS-scale dynamic model that considers nitrogen flows between livestock, plant, and soil compartments. Plant production is a function of soil mineral nitrogen levels, and livestock numbers depend on feed availability. The three FS are characterised by different crop-grassland-livestock balances: (i) field crop (Plateau Picard), (ii) intensive monogastric (Bretagne Centrale), and (iii) extensive ruminant (Bocage Bour-bonnais). The three scenarios consist of different combinations of synthetic nitrogen fertilisers and feed import availability declines until 2050: a decrease in synthetic fertilisers only (Synth-), a decrease in feed imports (Feed-), and a decrease in both external inputs (Synth-Feed-).RESULTS AND CONCLUSIONSThe first two scenarios highlight the positive role of livestock effluents and permanent grasslands on the robustness of food production. In the Synth-Feed- scenario, the extensive ruminant FS exhibits robustness (no decline in food production) for 13 years, whereas the field crop FS exhibits robustness for 4 years. In contrast, the intensive monogastric FS shows decreased food production within the first year. The difference between the two crop-livestock FS can be explained by livestock density, herd composition but also plant cover composition. In the long term, all three FS show a decrease in food production between 45 and 60%.SIGNIFICANCEOur modelling work shed some light on the role of ruminants and permanent grasslands in making FS more robust to decreases in synthetic fertiliser and feed import availability, increasing the time without production decline after the beginning of the perturbation. For longer-time resilience, configurational changes are still necessary, however a greater robustness gives more time to implement them, therefore facilitating adaptation and transformation. Our model paves the way to the study of resilience of FS from the point of view of their crop-grassland-livestock configuration and their dependence on external inputs.

International audience; Achieving food and feed self-sufficiency is important for both China and the world. While China's food self-sufficiency has been examined at the national and provincial levels, few studies consider lower administrative levels or different food and feed items. This study quantifies self-sufficiency in the eastern regions of China and examines correlations with agronomic (arable area, yield, fertilizer input, and machinery power) and socioeconomic (population density, gross domestic product [GDP]) variables at the local level, which are related to the interactions of the Sustainable Development Goals. We calculated food and feed balances, and checked correlations across and within regions grouped by population density levels between production, balance indices, and other agronomic and socioeconomic variables. The results showed that most regions can achieve self-sufficiency in cereals, vegetables, and meat. Regarding eggs and maize, there was self-sufficiency in the north but deficiency in the south. Nearly all regions demonstrated extreme shortages of milk and soybeans. The results also showed a positive correlation between the production of some food commodities and the population in eastern regions of China, demonstrating that the aim of achieving food self-sufficiency at the local level is pursued. For cereals, vegetables, and maize, the yield and arable land per capita were positive factors for self-sufficiency, while GDP per capita was a negative factor for cereals, meat, and maize. Various factors have different impacts on the food and feed self-sufficiency of regions based on population density. Protecting arable land by rural revitalization and mitigating urban sprawl can retain food and feed self-sufficiency in large cities. This study outlines important implications for policymakers seeking to achieve food and feed self-sufficiency in China.