When ancient meets modern – effect of plant-derived carbon on anaerobic decomposition in arctic permafrost soils (PANDA)


Main funder


Funds granted by main funder (€)

274 539,00


Funding program

Postdoctoral Researcher, AoF (Academy of Finland)


Project timetable

Project start date: 01/09/2018

Project end date: 31/12/2021


Summary

Arctic warming enhances mobilization of the vast carbon (C) pool stored in permanently frozen ground, causing increased release of carbon dioxide (CO2) and methane (CH4) to the atmosphere. To better constrain the magnitude of this permafrost C feedback to climate change, incubation studies are increasingly done to study the inherent decomposability of organic matter in arctic soils. These experiments, however, do not represent well the actual decomposability in the nature, where the vegetation, soil and microbes intimately interact. In addition, most of the incubation studies are done in the presence of oxygen, while anaerobic decomposition processes are understudied.
In PANDA, I will explore how fresh, plant-derived C affects anaerobic decomposition of soil organic matter and associated CO2 and CH4 production in arctic soils. Research material will be collected at five Arctic sites including soils that are 1) currently water-logged or 2) are currently well-aerated/frozen but will become anaerobic due to permafrost thaw.
I will establish a series of anaerobic incubation experiments with and without C amendments, imitating root exudation by plants. Labelling experiments will be conducted to track the flow of C into all relevant C pools, including CO2, CH4, DOC and microbial biomass, allowing partitioning of C release between soil organic matter and fresh C. These experiments will show, for the first time, that anaerobic C decomposition and CH4 production is stimulated (primed) by fresh plant-derived C and thus provide valuable knowledge on the lability of permafrost C in the absence of oxygen. Studies on the microbial community composition, exoenzyme activities and targeted sequencing of functional genes of different methanogenic pathways will provide mechanistic understanding on the changes in the anaerobic decomposition observed in the incubations – knowledge, which is valuable to develop predictive models. Laboratory experiments will be complemented by field studies which involve flux measurements and 14C datings of CH4 providing rare information on the age of CH4, as well as field-data on the priming effect.
The project will be supported by a strong international network of collaborators covering all components of the study from permafrost C dynamics to molecular biology and radiocarbon techniques. I am convinced that the results of this project will have high potential to redirect future research on permafrost C cycling.


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Last updated on 2020-08-10 at 09:25