The increasing trend of larch forests burning in the permafrost zone (60–65° N, 95–105°E) is observed in Siberia. More than 10% of entire larch forests were damaged by wildfire during the last 15 years. Post-fire effect might determine long-term dynamics of the seasonal thawed layer.

The increasing trend of larch forests burning in the permafrost zone (60–65° N, 95–105°E) is observed in Siberia. More than 10% of entire larch forests were damaged by wildfire during the last 15 years. Post-fire effect might determine long-term dynamics of the seasonal thawed layer.

Current research analysed the reflectance and thermal anomalies of the post-pyrogenic sites under the conditions of permafrost. Studies are based on long-term Terra, Aqua/MODIS (Moderate Resolution Imaging Spectroradiometer) survey for 2006–2018. We used IR thermal range data of 10.780–11.280 microns (MOD11A1 product) and we evaluated NDVI from MOD09GQ product as well. The averaged temperature and NDVI dynamics were investigated in total for 50 post-fire plots under different stages of succession (1, 2, 5 and 10 years after burning) in comparison with non-disturbed vegetation cover sites under the same conditions.

We recorded higher temperatures (20–47% higher than average background value) and lower NDVI values (9–63% lower than non-disturbed vegetation cover) persisting for the first 10 years after the fire. Under conditions of natural restoration background temperature anomalies of the ground cover remained significant for more than 15 years, which was reflected on long-term satellite data and confirmed by ground-based measurements.

To estimate impact of thermal anomalies on soil profile temperature and thawed layer depth we used the Stefan’s solution for the thermal conductivity equation. According to results of numerical simulation, depth of the seasonal thawed layer could increase more than 20% in comparison with the average statistical norm under the conditions of excessive heating of the underlying layers. This is a significant factor in the stability of Siberian permafrost ecosystems requiring long-term monitoring.

This research was supported by the Russian Foundation for Basic Research, project No 17-04-00589, Government of the Krasnoyarsk region, project No 18-41-242003.