Balance between dairy cows’ production and supporting ecosystem services in highlands pastures

Mountain pastures are agro-ecosystems depending on livestock farming and providing a large spectrum of services. Nowadays, these systems are facing social, economic and climatic challenges that threaten their equilibrium and externalities. This study aimed at characterising the relationships between grazing livestock, land morphology, and the microbial community of mountain pastures. Four different mountain pastures of Italian eastern Alps, grazed by dairy cows producing milk for PDO cheese, were considered during multiple summer transhumance (from mid-June to mid-September). Herd size (average ± SD) was 74±56 dairy cows, pasture surface 165±77 ha, and elevation 1,990±81 m asl. The study was developed at different spatial scales, with a particular focus on the supporting ecosystem services linked to the nitrogen cycle. At a macro scale, cattle movement was GPS-tracked to estimate individual grazing patterns and map the local intensity of grazing. Daily distance travelled by cows was 8.0±3.8 km. At a micro scale, pasture soils were characterised with a molecular approach to obtain the nitrification (copies of bacterial and archaeal amoA genes) and denitrification potentials (copies of nosZ genes) genes. Slope was the most important morphological variable at both spatial scales, determining animal movement patterns, also between breeds, and the nitrification potential of soils, which increased at lower slopes. In contrast, the denitrification potential (nosZ gene copies) of grazed areas was unaffected by land morphology. In addition, amoA Archaea showed a much higher residual variability than nosZ. The knowledge of how grazing patterns and environmental conditions determine individual productivity and soil supporting ecosystem services can be used to develop good practices for the sustainable management of mountain livestock-grassland systems. Identifying multi-purpose pasture management practices may increase the resilience of grazing agro-ecosystems while maintaining the productivity of local livestock systems.