Silvopastoralism and adaptive multi-paddock grazing promote soil carbon stability and soil biodiversity

Managing livestock on pastures that combine silvopastoralism and improved grazing management practices could increase carbon (C) storage in the soil, enhance biodiversity, and mitigate climate change. However, these systems are not widely used, and data on the impact of silvopastoralism and grazing management are scarce in temperate agroecosystems. To remedy this, we have set up a long-term experiment in 2020 under real farming conditions at the Lafontaine-Noël Farm in Dupuy, Quebec, Eastern Canada. Our objective is to compare a silvopastoral system, where adaptive multi-paddock grazing (AMP) is carried out between agroforestry hedges, with a conventional system where grazing is carried out continuously. We evaluated, in the shallow rhizospheric soil (0-10 cm), the effect of grazing modes and tree species on (1) C stocks and stability by measuring its distribution in the particulate (POM) and mineral-associated (MAOM) fractions of soil organic matter, and (2) underground biodiversity and its variability by analyzing environmental DNA from the rhizospheric soil. Our results show that AMP grazing stabilizes more C in MAOM and increases the bacteria/fungi ratio compared to continuous grazing. In agroforestry hedgerows, hybrid poplar and white spruce store more stable C in MAOM and in the entire soil than red maple. These results indicate that combining silvopastoralism and adaptative multi-paddock grazing is promising avenue to improve the agri-environmental performance of farms in regions of the world where livestock farming plays an important socio-economic role.