ECTOARC

Ectomycorrhizal fungi and the stability of soil organic matter in a changing Arctic

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 Obiettivo del progetto (Objective)

'The Arctic is currently facing large changes in climatic conditions, with expected consequences for the vulnerable terrestrial ecosystems. Arctic ecosystems contain a large proportion of the global soil carbon stock, and there is a risk that environmental changes will lead to a release of carbon dioxide from this pool substantially amplifying the atmospheric warming potential. However, populations of plants and microorganisms will likely change with changed environmental conditions. An increased abundance of plants associating with ectomycorrhizal (EM) fungi has already been observed across the arctic tundra biome as a response to recent warming, and this trend is expected to continue. Recent research suggests that EM mycelia contribute disproportionately relative to plant inputs to soil organic matter formation. Hence, increased abundance of EM plants and fungi could partly counterbalance the expected respiratory loss of carbon from tundra soils in the future. However, EM fungi also contribute to the degradation of organic matter by producing extracellular enzymes thereby decreasing carbon storage. It is crucial to sort out which of these mechanisms dominate in different ecosystems and under different environmental conditions in order to build reliable conceptual and predictive models describing the future carbon balance of the Arctic. This project is the first to explore the role of EM fungi as drivers of soil carbon dynamics in the Arctic in relation to global change. The project explores responses of EM fungi at three interlinked levels, that is, their abundance, species composition and functioning, to long-term field experiments simulating climate change in the sub- and high arctic. The project combines methods to measure ecological pools and processes (soil C and N pools, 13C and 15N natural abundance) with novel methods for studying EM community composition and functioning (fungal ingrowth bags, molecular community analyses, exoenzyme production).'

Introduzione (Teaser)

As the first signs of global warming appear at the Earth's poles, concern is growing for the sensitive ecosystems located in these regions. Recent research has identified a more important role for soil-based microorganisms in the carbon cycle than previously thought.

Descrizione progetto (Article)

As global warming set its sights on the polar regions, it is not known how the unique flora and fauna in this region will respond to the changing climate. In fact, there is fear that stores of carbon locked up in Arctic soils may be released as temperatures rise, further aggravating the situation.

Whether or not this threat is realised may depend on tiny microorganisms in the soil, known as ectomycorrhizal fungi, which help regulate nutrient exchange. Funding from the EU was allocated to study this aspect in detail in the context of the 'Ectomycorrhizal fungi and the stability of soil organic matter in a changing Arctic' (Ectoarc) project.

Experiments were carried out in arctic and boreal forests and heaths in Sweden using a number of advanced molecular and genetic techniques. It was discovered that elevated levels of ectomycorrhizal fungi activity were correlated with both increased tree growth rates and humus production. This strong influence on the carbon cycle must be accounted for in models in order to improve the accuracy of predictions of the future state of these ecosystems and the climate.

Another interesting finding during Ectoarc was the incredible variety of taxa of ectomycorrhizal fungi, many of which had never before been observed. Several scientific articles have been published and new research collaborations have also been established. This work will be of value to users of these ecosystems as well as policymakers and stewards of these valuable natural resources.