Assessing climatic exposure of grassland-based livestock systems with seasonal-scale indicators.

Research aiming to reduce the vulnerability of agricultural systems to climate variability and change requires practical appraisal of their climatic exposure. We propose a method to map local climatic conditions over a given period to a set of productivity and management-related indicators that are specific to grassland-based livestock systems. Our method based on a reference system balances herbage production and feed requirements over a long period (≥ 30 years) and provides boundaries for productivity-defined seasons and indicators for surplus or shortage of herbage at seasonal and annual scales. This exposure-assessment method was applied to five climatically contrasting locations in south-western France. The trends and variability of the exposure indicators were analysed for past (1980-2010) and future (2035-2065) periods, considering the A1B scenario of the IPCC. Despite high year-to-year variability and the heterogeneity of the climatic situations studied, we show that climate change can modify the boundaries of productivity-defined seasons and seasonal herbage surplus or shortage. Moreover, the exposure indicators succeed in detecting climate-induced changes and distinguishing situations where a classical exposure indicator, such as annual forage production, could not. The exposure indicators highlight the forage productivity and the timing of production associated with local climatic conditions. These features fit the temporal scale at which farmers consider farm management and are highly suitable for identifying adaptation strategies that reduce the vulnerability of grassland-based livestock systems. [ABSTRACT FROM AUTHOR]