Scanning soil biodiversity in long term Agroforestry system in temperate climate: results from central Italy

Soils have recently become part of the global carbon agenda for climate change mitigation and adaptation through the launch of high-level initiatives. Last year, FAO launched the RECSOIL program with the intention of increasing attention to management practices that increase soil organic carbon (SOC) and can partially mitigate carbon emissions. Recarbonisation of soil by current SOC stocks maintenance and fostering SOC sequestration, has positive effects on soil structure, water retention and nutrient supply and is critical for supporting ecosystem services and agricultural productivity (FAO). In this context, agroforestry, one of the most ancient agricultural practices of the Mediterranean culture and partly lost due to agricultural intensification, has recently been reintroduced for its positive effects on the SOC sequestration (FAO and ITP 2021). In fact, agroforestry systems positively improve the resources of the agroecosystem by providing numerous advantages as reported in experiments performed, in recent years, on tropical areas. By contrast, long-term agroforestry (LTA) studies in temperate climate are still lacking. Temperate LTA studies focusing on the soil biota communities and relative roles of the ecological drivers of organic carbon dynamics are extremely interesting and deserve to be analyzed. This survey aims to provide monitoring tools and to highlight specific "biological traits" and / or ecological relationships for the assessment of soil quality and to define appropriate biodiversity indicators useful for providing functional information relating to ecosystem services. During spring and autumn 2021, we analyzed some components of soil biota: mesofauna and microbial fungal communities. Particular attention was given to collembola and possible relationships with fungi, as these can significantly influence the soil carbon cycle and the related trophic network. The study was conducted inside an area of “ Tenuta di Paganico”, an extensive farm devoted to organic agro-zootechnical productions in central Italy based on silvopasture practices of the local Maremmana cattle breed. The methodology was developed along a gradient based on land use (Mediterranean forestry, Silvopastoral and Grassland) and on the intensity of grazing as a function of the maximum distance that animals usually reach from the main feeding stations (high density pastures with lower distance from the station feeder and low-density pasture at greater distance). The first results showed a substantial trend in how some silvopastoral practices can better preserve soil biodiversity, with a high level of abundance of mesofauna and fungal biodiversity, as well as soil biological quality and ecological stability, if managed in a way rational. If forest pasture is not properly managed and livestock is persistently on the ground, biodiversity levels drop dramatically and the benefits of silvopastoral practice are not realized. Further analyses will be necessary to 1) deepen understand and highlight the complex interactions between biological communities and physicochemical variables, all of which contribute to the overall quality of soils; 2) explore if interactions can be reliable enough to be applied for soil quality monitoring and management.