Thermokarst lake expansion and infilling rates in the Tavvavuomapeat plateau complex, northern Sweden

The permafrost region has recently experienced an increased attention, due to projected climatechange and resource development. In permafrost landscapes, thermokarst lakes are commonfeatures. These water-filled collapse features form when ice-rich ground thaws. Thermokarstlakes are dynamic and change naturally in size due to erosion and/or infilling of fen vegetationalong lake shorelines. When they are formed, thermokarst lakes emit large amounts of carbon inform of the greenhouse gases methane (CH4) and carbon dioxide (CO2). Quantifying rates ofthermokarst lake expansion and infilling of fen vegetation by cardinal direction can help ourunderstanding of thermokarst lake dynamics. This study quantifies rates and extent ofthermokarst lake expansion and infilling of fen vegetation by cardinal direction for the timeperiods 1963-1975 and 1975-2003, in Tavvavuoma peat plateau complex, northern Sweden.This is done using the ArcGIS extension Digital Shoreline Analysis System (DSAS). The rateswere less than 0.1 m/yr, and lake expansion was greater than infilling between 1963 and 1975.For the 1975-2003 period, infilling of fen vegetation was greater than lake expansion. Thedirectional patterns for expansion and infilling of fen vegetation could potentially explained beby wind direction for different seasons, but the patterns are far from uniform in all lakes,indicating that local properties like lake depth, lake size and shape and the surrounding peatdepth and permafrost depth and temperature also might affect the activity in the lakes.