Closely integrated crop and livestock production systems used to be the rule in agriculture before the industrial revolution. However, agricultural landscapes have undergone a massive intensification process in recent decades. This trajectory has led to uniform landscapes of specialized cropping systems or consolidated zones of intensive livestock production. Loss of diversity is at the core of increasing side effects on the environment from agriculture. The unintended consequences of specialization demand the reconciliation of food production with environmental quality. We argue that the reconnection of grazing livestock to specialized crop landscapes can restore decoupled biogeochemical cycles and reintroduce the necessary complexity to restore ecosystem functioning. Besides, the reconnection of crops and livestock promotes several ecosystem services underlying multifunctionality. We focus on the capacity of integrated crop-livestock systems to create biophysical and socioeconomic resilience that cope with weather and market oscillations. We present examples of redesigned landscapes that leverage grazing animals to optimize food production per unit of land while mitigating the externalities of specialized agriculture. We also debate mindset barriers to the shift of current specialization trends toward the design of multifunctional landscapes.
We explored the effects of heterogeneity of sward height on the functioning of grazing systems through a spatially implicit mechanistic model of grazing and sward growth. The model uses a population dynamic approach where a sward is spatially structured by height, which changes as a function of defoliation, trampling, and growth. The grazing component incorporates mechanisms of bite formation, intake, and digestion rates, but excludes sward quality effects. Sward height selection is determined by maximization of the instantaneous intake rate of forage dry mass. For any given average sward height, intake rate increased with increasing spatial heterogeneity. Spatio-temporal distribution of animal density over paddocks did not markedly affect animal performance but it modified the balance of vegetation heterogeneity within and between paddocks. Herbage allowance was a weak predictor of animal performance because the same value can result from multiples combinations of herbage mass per unit area, number of animals, animal liveweight, and paddock area, which are the proximate determinants of intake rate. Our results differ from models that assume homogeneity and provide strong evidence of how heterogeneity influences the dynamic of grazing systems. Thus, we argue that grazing management and research need to incorporate the concept of heterogeneity into the design of future grazing systems.
Context Average sward height has traditionally been used as a grazing management variable. However, such approach ignores the spatio-temporal heterogeneity of swards. Because the intake rate responds non-linearly to average height at plant level, we expected that sheep exposed to contrasting grazing methods with similar average heights would behave differently. Aims We hypothesised that low-intensity, high-frequency grazing results in a higher daily intake rate than does high-intensity, low-frequency grazing, despite both methods having similar average sward heights over space and time. Also, we asked whether sheep exhibit the same foraging mechanisms for a given instantaneous sward state regardless of long-term grazing conditions imposed. Methods We exposed sheep to two contrasting grazing methods with similar average height; low-intensity, high-frequency (LIHF), and high-intensity, low-frequency (HILF). We then evaluated their foraging behaviour using continuous bite-monitoring paired with detailed sward measurements during grazing down. Key results Sward height decreased markedly during the grazing period in both treatments, but the sward height depletion was faster under HILF (7.5 cm and 20.3 cm for LIHF and HILF), which means that sward structure was severely disrupted. The animals exhibited markedly different herbage intake patterns between the grazing methods, with sheep under LIHF presenting greater total daily herbage intake (850 vs 630 g DM per individual). Also, sheep demonstrated a more stable and higher instantaneous intake rate in the LIHF. Despite the difference in total daily herbage intake, the grazing treatments did not affect the behavioural mechanisms beyond their indirect effects on the rate of change in the instantaneous sward conditions. Grazing treatments created different patterns of sward change and intake rate over time, but the local and instantaneous sward conditions determined intake rate regardless of the grazing method. Conclusions Intake responses of sheep differed between grazing methods with similar average height due to sward heterogeneity over time and space. Grazing mechanisms were not directly affected by the treatments but were influenced by the sward heterogeneity imposed by the grazing management. Implications Grazing management requires not only consideration of the average sward height, but also an understanding of how the resource is distributed in time and space.
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