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Impacts of PermaFROST degradation on peatLAND biogeochemistry

Periodic Reporting for period 1 - FROSTLAND (Impacts of PermaFROST degradation on peatLAND biogeochemistry)

Berichtszeitraum: 2021-11-01 bis 2023-10-31

The degradation of permanently frozen ground (permafrost) has accelerated in subarctic and arctic regions. The southern limit of permafrost distribution has advanced northwards over the last decades, and the degradation has also increased in the northernmost arctic zone. This is expected to persist in the future due to climate warming, which is more notorious in circumpolar regions. Almost half of the world’s soil organic carbon is stored in permafrost, largely in permanently frozen peat (un-decomposed plant material). The degradation of permafrost in peatlands is particularly threatening because it may turn peatlands from carbon sinks to carbon sources and accelerate greenhouse gas emissions and climate change. However, the interdependency between carbon and nutrient cycles is still poorly understood, and needs to be addressed to properly understand the impacts of permafrost thawing on the functioning of peatland ecosystems and their feedback on global climate. FROSTLAND addresses some of these uncertainties. The overall aims are to elucidate the biogeochemical changes occurring in permafrost across gradients of permafrost thaw in subarctic and arctic peatlands and to improve fine- and broader-scale estimates of nutrient availability and of C and nutrient stocks in different global warming scenarios. This information will be crucial for society to improve the accuracy of predictions regarding the impacts of permafrost thaw on global climate.
Firstly, new data were collected to build a unique and large dataset of biogeochemical variables from different arctic regions (Alaska, Canada and Sweden). The new data were merged with other data that had been already collected in subarctic and arctic permafrost peatlands by the researcher in previous research projects. In summer 2022 the Belgian team (FROSTLAND) joined forces with a research team from the University of Vienna to conduct an expedition in Northern Canada. The expedition was based in Inuvik, and was logistically supported by the Aurora Research Institute (ARI). Once the research permissions were approved the expedition took place. From this town the tundra in the continuous permafrost area was easily reached. We selected a sampling area where we could follow a similar sampling strategy as that done in Sweden and Alaska in previous campaigns, thereby encompassing areas with intact permafrost and degraded permafrost. To do so, we selected several study sites, including areas with intact permafrost and areas where permafrost had thawed across different types of peatlands. We collected a total of 21 soil cores with an engine coring auger, from intact permafrost features and collapsed features that were highly representative of the landscape of the region. The plant and soil samples were then processed in the lab.

Over the course of the project part of this large dataset was analysed. This led to a first scientific manuscript entitled 'Major biogeochemical changes in soils, microbes and plants along gradients of permafrost thaw in a subarctic mire', that will be published in a scientific journal. The remaining data will be presented for the first time in the European Conference on Permafrost in June, where a comparative study amongst subarctic and arctic zones will be presented. The results have also been disseminated to the general audience by participating in workshops, conferences and seminars or by posting in a blog.The researcher has also raised awareness of the importance of permafrost on global climate regulation as member of the scientific committee of the Master in Planetary Health (Open University of Barcelona)

Another aspect that was addressed in this project was the collection of imagery data from an Alaskan region for which biogeochemical data was available from a previous campaign and also for the Canadian sites that were sampled in 2022. For this task we used high-resolution imagery obtained with drone-based technology to examine fine-scale variability of permafrost condition across the peatlands studied in Alaska. This allows a better modelisation of the permafrost condition across a large area and the upscaling of the results at a coarser scale.
Despite the early termination of the project, the research has provided the opportunity to compile a unique dataset on biogeochemical data of permafrost ecosystems in arctic and subarctic systems. The data will be used for the publication and dissemination of results as the researcher will still be involved with the management of the dataset, and a PhD will continue with the analyses of the dataset. The major finding of the research conducted to date is that changes in permafrost condition originate major impacts on the ecosystem in terms of nutrient cycling. Namely, the degradation of frozen ground releases large amounts of carbon and nutrients that are cycled and mobilised for the first time after being frozen for thousands of years. This larger availability of nutrients accelerates the bioegeochemical cycles and this may become a threat for the stability of ecosystems in northern areas. Thanks to this project we now know that not only carbon but also large amounts of phosphorus and nitrogen are released from degrading permafrost, which may further accelerate microbial activity, increase the decomposition of organic matter and the emission of greenhouse gases. This represents a positive feedback for climate warming that should be implemented in climate predictions due to its enormous impacts on society.
scientific team involved in the field campaign in Arctic Canada