We anaerobically incubated soil samples from a polygon center (P2, 72° 22.3 N, 126° 29.9 E) on Samoylov, Northeast Siberia at 4°C for 60 days. We used three soil layers ((i) surface active layer, (ii) bottom active layer, (iii) permafrost) and two treatments ((i) control which remained at 4°C for 60 days, (ii) FT with two 30-day periods at 4°C separated by one frost event (-18°C)). For each sample we used 3 aliquots. CO2 and CH4 production were measured via gas chromatography.