Evaluating the sustainability of Montado farm's pastures: Insights from emergy and nitrogen footprint assessments of pastures with reduced productivity

The Montado ecosystem, a Mediterranean agro-silvo-pastoral system, plays a vital role in sustainable livestock production, yet faces increasing challenges from climate variability and pasture productivity decline. This study evaluates the sustainability of two Montado farms integrating cattle and sheep production by applying emergy and nitrogen footprint assessment under three different pasture productivity scenarios. Emergy indicators highlight the reliance on external resources during droughts, while nitrogen (N) footprint analysis underscores the potential environmental costs of maintaining livestock productivity under such conditions. Results indicate that cattle production is more emergy-efficient under regular pasture productivity, whereas sheep production consistently exhibits lower N losses and lower sensitivity to pasture decline. Integrating emergy and N footprint assessments reveals that increasing reliance on external feed to compensate for pasture reduction leads to higher resource dependence and N losses, particularly in cattle systems. These findings support management strategies that prioritize pasture-based feeding, promote legume-rich pastures to enhance N efficiency, and encourage mixed sheep–cattle systems as a means to buffer sustainability trade-offs under increasing climatic variability.