Mycorrhizas are symbiotic associations between soil fungi and most plant species. Despite its recognized ecological relevance, quantitative information about the abundance patterns of distinct... Show moreMycorrhizas are symbiotic associations between soil fungi and most plant species. Despite its recognized ecological relevance, quantitative information about the abundance patterns of distinct mycorrhizal plants and fungal types and their environmental drivers and ecological implications across different biomes is incomplete. This thesis quantitatively explores the aboveground and belowground abundance patterns of arbuscular mycorrhiza, ectomycorrhiza and ericoid mycorrhiza and the ecosystem properties derived from these patterns. Taken all together, the chapters of this thesis highlight the need of considering the specific environmental context when assessing mycorrhizal impacts on ecosystem functioning. Evaluating mycorrhizal-mediated ecosystem processes based solely on the abundance of AM, EcM and ErM plants may be misrepresentative. Specific climatic conditions, the abundances of the fungal partners, the microbial community composition or species-specific plant and fungal traits should also be taken into account. New theoretical frameworks need to be developed that allow more accurate predictions on mycorrhizal influence on biogeochemical cycles. Show less
This thesis describes the role of pollution, specifically neonicotinoid insecticides, as an actor of the ongoing biodiversity decline. Using a new research facility, the Living Lab, the effects of... Show moreThis thesis describes the role of pollution, specifically neonicotinoid insecticides, as an actor of the ongoing biodiversity decline. Using a new research facility, the Living Lab, the effects of field relevant concentrations of neonicotinoids and fertilizers to aquatic invertebrates was assessed in 36 experimental ditches. This showed that neonicotinoids had profound impacts on both single species as well as macroinvertebrate biodiversity and had severe consequences for the ecosystem processes the invertebrates fulfilled. Many of the results found in this thesis have not been discovered before because of the simplicity of standardized ecotoxicological testing, which not fully incorporates the myriad of ecological factors governing toxicity. It was found that the addition of fertilizers directly stimulated primary production which in turn reduced toxic effects indirectly. In addition, the neonicotinoid thiacloprid induced indirect effects on aquatic biodiversity which persisted much longer than the presence of this insecticide in the ditch ecosystem. The results in this thesis therefore show how the inclusion of environmentally realistic testing is essential to predict the actual risks of agrochemicals in the actual environment. Show less
