Date created: | Last Updated:

Category: Project

Description: This is the data repository of the project "Integrated assessment to aid mitigation of negative impacts by THREE global change Drivers on alpine biodiversity and ecosystem function". The project is a Miljøforsk research project funded by the Norwegian Research Council (Project Number: 287801). Mountain areas provide important habitats for many plant and animal species, but they also contribute with important ecosystem functions and services such as carbon storage, areas for livestock grazing, and regulation of floods and landslides. At the same time, mountain ecosystems are particularly vulnerable to climate change. Climate warming, nitrogen deposition and grazing are important global change drivers with impacts on biodiversity and carbon cycling. Both climate warming and nitrogen deposition increase nutrient availability and therefore biomass and plant productivity, often with negative impacts on biodiversity. Further, these drivers can increase carbon storage in the soil because of increased decomposition of organic plant material. Grazing also increases the nutrient input and productivity in ecosystems, but at the same time reduces biomass. The intensity of grazing is however important for how grazing affects biodiversity and carbon storage. The effects of each single driver are quite well understood. But in a natural system, these drivers will interact with complex effects on the ecosystem. In THREE-D we investigate these complex interactions on biodiversity and ecosystem functioning using a field experiment. We will expose an alpine plant community to warmer climate, nitrogen deposition and different grazing pressure and study the effects on biodiversity and carbon cycling. Further, we will study how different grazing intensity can reduce these negative impacts on ecosystem functioning. Specifically, two research questions will be addressed: - How does graazing interact with climate warming and/or nitrogen deposition and affect biodiversity and ecosystem functioning in an alpine ecosystem? - When and at what level does grazing mitigate the effects of these two global-change drivers on biodiversity and ecosystem functioning? Parallel experiments will be run in Norway and China in alpine ecosystems, where we expose an alpine plant community to warmer climate (transplant to lower elevation), increased nitrogen deposition (N addition), and different grazing levels in a fully factorial design to assess and disentangle their combined effect on biodiversity and ecosystem function. Our hypotheses are: H1: The effect of grazing on species composition (biodiversity) along a productivity gradient varies from facilitation loss in low-productivity plant communities to competitive release in highproductivity plant communities. H2: A decrease in species composition (biodiversity) due to warming and/or nitrogen deposition can be mitigated at an intermediate grazing level. H3: Grazing will stimulate overall ecosystem carbon fluxes (respiratory CO2 release and photosynthetic uptake) at low productivity. (WP3) Conversely, at high productivity, the effect of grazing on ecosystem carbon fluxes depends on the relative importance of the different mechanisms: rate of decomposition, increase in carbon fluxes, and change in species composition. H4: Intermediate grazing can, to some degree, mitigate negative impacts on ecosystem carbon fluxes from warming and/or increased nitrogen deposition. We will also develop a management decision-support tool, in collaboration with farmers and local conservation managers, to estimate the impact of the current level of grazing and to explore the potential of adaptation of the grazing regime to meet new pressures and/or optimise ecosystem service delivery in an alpine ecosystem.