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Project Topic
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Biological diversity is of pivotal importance for ecosystems. Most studies on the importance of diversity for ecosystem functioning have targeted aboveground communities. However, a large part of biodiversity is literally hidden below ground. The consequences of soil biodiversity losses for ecosystem functioning are still poorly understood. This is particularly true in agro-ecosystems, where soil biodiversity declines upon land use intensification are commonly reported. We have previously shown that belowground diversity is key for maintaining multiple ecosystem functions (i.e. multifunctionality) in model ecosystems, and that particular functional groups of soil biota affect ecosystem sustainability by reducing greenhouse gas emissions, immobilizing nutrients and influencing nutrient losses. Here, we build upon those studies and test, for the first time, whether agro-ecosystem diversification can promote soil biodiversity and the delivery of beneficial ecosystem services across Europe. Our central hypothesis is that increased plant diversity will promote belowground biodiversity and related ecosystem services. Digging deeper aims to enhance our understanding of belowground biodiversity and management for ecosystem functioning and service delivery in European agroecosystems through four key objectives: 1) Quantify the impact of land use/agricultural practices, in particular those increasing plant diversity, on soil communities, ecosystem functions and services. 2) Determine the role of soil diversity and biological interactions for multifunctionality of European agroecosystems. 3) Assess the impacts of climate change on the provision of ecosystem services by agroecosystems from different climatic zones, management practices and soil biodiversity levels. 4) Identify innovative land management practices that maximize the delivery of multiple ecosystem services delivered by soil biota. To address these objectives, we will establish a pan-European network (from Sweden to Spain) of 250 agricultural fields that vary in aboveground diversity. This network includes sites from low to high above ground diversity, as well as field experiments where the diversity of agro-ecosystems is manipulated in time or space (e.g. through crop rotation, cover crops, or intercropping). We will assess below-ground diversity using high throughput sequencing and we will measure a number of ecosystem functions (plant yield, nutrient cycling, soil aggregation and soil C sequestration, soil N2O sink) acting as surrogates of essential services in agroecosystems. Subsequently, we will use advanced statistical tools to assess the impact of above- and belowground diversity and management on both multifunctionality and individual ecosystem services. We will use different multifunctionality indexes, focused either on production, biodiversity and environmental sustainability. These different scenarios will be selected based upon discussions with stakeholders in each country. In a next set of experiments we take a more mechanistic approach. We will collect soil cores from field sites with low, medium and high soil biodiversity. These cores will be brought to the greenhouse and nutrient cycling and aggregate stability and greenhouse gas production will be assessed and related to soil biodiversity, soil characteristics and agricultural management. Following this, we will manipulate soil biodiversity by filtering organisms according to size, and will use these soils as inoculum for a novel experimental system to test whether changes in soil biodiversity influence multifunctionality and individual ecosystem services. We will focus on the role of soil biota for N, P and C-cycling, including some poorly understood processes. We will test whether enhanced levels of aboveground diversity enhance soil ecosystem functions through positive effects on soil biodiversity. Finally, soil cores with different above and belowground diversity levels will be subjected to different climate change scenarios (enhanced temperature and reduced precipitation) using a common garden experiment. Using this system, we will test whether agro-ecosystem diversification promotes the resistance of ecosystem services to climate change. Together with stakeholders and policy makers we will develop a theoretical and applied framework to identify the impact of agricultural practices on the yield, biodiversity and sustainability of agroecosystems. The results will be implemented at the national (through meetings, press releases and publications targeting farmers, advisors and policy makers) and European (through a policy paper and communications to policy makers) levels. Overall, this project will provide a comprehensive overview on the impact of agro-ecosystem diversification on soil biodiversity and soil ecosystem service delivery in Europe, as well as novel insights of how we can maximize the provision of ecosystem services by soil biota through aggricultural practices.
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