Alberta van Gent

The interaction between spatial soil moisture and temperature variability in a permafrost peatland in Tavvavuoma

Date, time and venue: 2th of March, at 13:15, in Ahlmannsalen
Supervisor: Britta Sannel and Stefano Manzoni
Examiner: Peter Kuhry
Master's Programme in Glaciology and Polar Environments
Degree Project in Physical Geography and Quaternary Geology, 45 credits

Presentation language: English

Abstract
Permafrost peatlands are important ecosystems in the Arctic and are closely linked to uptake and release of greenhouse gases. Unfortunately, many of the Arctic permafrost peatlands are subjected to degradation due to changes in temperature and hydrology in the area. As such, changes in temperature and hydrological conditions can stimulate the thawing of permafrost soils, and hence remobilizes the stored carbon. The remobilization of carbon can either occur through emission of carbon dioxide (CO2) or methane (CH4). Since the Arctic stores large amount of soil carbon and is highly susceptible to thawing, permafrost peatlands are seen as biochemical hotspots in the warming Arctic. Tavvavuoma is a large permafrost peatland, with a landscape characterized by microtopography; consisting of palsas, peat plateaus, thermokarst lakes, hummocks, depressions and fens. Spatial and temporal variations in volumetric water content (VWC) and soil temperatures were assessed and connected to thermal properties of permafrost. The distribution of the plateaus, depressions and fens were found to be closely related with the differences in VWC and soil temperature. With the lowest VWC and soil temperature occurring on the plateaus and the highest VWC and soil temperature occurring in the fens. The results from the spatial patterns also showed a VWC increase with depth, both on the plateaus and the depressions. In addition, the spatial pattern of the temperature showed a soil temperature increase with depth on the plateaus and a more or less constant soil temperature over depth in the depressions. The found hydro-thermal properties were connected to the thermal state and carbon content of the peatland and based on another study carbon fluxes from the peat plateaus, depressions and fens in Tavvavuoma were estimated. Based on a gross estimate Tavvavuoma would likely be a net carbon source, with a net CO2 uptake and CH4 release. Moreover, the emission of these greenhouse gases most likely have a positive feedback, increasing temperatures and enhancing the impact on climate change. In addition, thawing permafrost results in more liquid water in the soils. The storage of either frozen or liquid water, in the permafrost soils, has distinct, complex consequences on the soil properties and thereby on the soil processes.

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