Soils are a medium in which plants root, but also house an overwhelming abundance and diversity of living organisms. The local composition and abundance of these organisms depends greatly on the identity of the plant that is growing in the soil. The performance of plants, in turn, is determined by interactions with soil organisms. Hence, via their specific effects on soil organisms, plants can influence the growth of other plants that grow later in the same soil. In this project I will examine the impact of such soil-borne ?legacy effects? on plants and aboveground insects in natural ecosystems. Plant-soil legacies can cause changes in the composition of plant communities and can change the aboveground chemistry of individual plants. Via these two mechanisms, soil organisms can influence aboveground organisms such as insects that directly or indirectly depend on the plants. I propose that soil-derived legacy effects of plants are important for the structure of natural ecosystems, determine its aboveground biodiversity, and can be used to restore degraded ecosystems. In the proposed project, I will study interactions between plants, soil organisms, and aboveground insects and examine when, how, and at what temporal and spatial scales plant-soil legacy effects influence aboveground plant-insect interactions in natural grasslands. The soil-legacy effects on aboveground plant and insect communities will be tested by reciprocal soil and plant transplantations in grasslands. In field experiments soil legacies will be manipulated via influencing plant communities. Microcosm studies will be used to disentangle the legacy effects of particular groups of soil organisms, and a general framework will be developed that predicts the impact of soil-legacy effects on plants and aboveground insects. This framework will be used to manage soil legacies to restore biodiversity in degraded grassland ecosystems, and in collaboration with restoration practitioners, this will be field-tested in restoration sites.

A time series was constructed of farm fields that were converted from conventional to organic farming. This time series covered more than 20 years of land-use transition to organic farming. In this time series, organic fields on clay had more labile organic carbon than conventional fields, especially in soils with low iron oxide content. Fungal diversity increases, and protist diversity decreases. In a long-term experiment, microbial activity in organic fields was higher than in conventional fields, especially in mid-summer months. The multi-functionality decreased with increasing land-use intensity.

Solar systems are implemented at increasingly large scale to meet demands for sustainable energy, including placing them on inland waters. SPARKLES unites scientists and stakeholders across domains (energy, ecology, society) to develop nature-positive solutions for floating solar for humans and nature. By putting nature front and center we look for integrative solutions that solve multiple problems in the living environment, rather than creating trade-offs between humans and nature.