Arctic ecosystems, which store a globally important amount of carbon (C) in the soil, experience most pronounced climate change. Climatic warming and the concomitant enhanced nutrient availability can accelerate decomposition leading to a loss of soil C. C ONAR will assess the currently unknown mechanisms behind this response with a focus on competition for nutrients within soil microbial communities and between microbes and plants in the Arctic. Samples will be taken from long-term warming and litter addition/fertilization experiments in Abisko, northern Sweden.
Novel radioactive isotope techniques will be used to determine limiting factors for bacterial and fungal growth, adaptation of microbial communities to higher temperatures and competition between plants and microbes for phosphorus. How climatic warming affects competition between fungi and bacteria in response to different C sources will be assessed by tracing 13C stable isotope label from different root zone model compounds into lipid biomarkers.
In situ 15N, 13C-labelling experiment, to be conducted in Abisko, will give information about competition between plants and microbes for organic N. Finally, near-infrared reflectance spectroscopy (NIRS) will be used to evaluate climate change-induced soil quality changes, and whether they are correlated with the microbial responses.
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