Carbon stocks of soils under forest in the Komi Republic of Russia

Soils are a large reservoir of organic carbon, and plays a significant role in its accumulation and storage. The goal of this study is to provide a generalized estimate of soil organic carbon (SOC) stocks at dominant types of forest soils in the European North-East of Russia. The soil cover of the studied territory is mostly formed by Histic Retisols (HsR), Haplic Retisols (HpR) and Albic Podzols (AP). We used the results of our own SOC estimates and the ones of soil profile descriptions that were published for the region of investigation. The calculation was carried out for organic horizons and depths of 0-30, 0-50 and 0-100 cm including the organic horizon. The literature data lacks bulk density (BD) information. We calculated the mean BD value for soil horizons based on our BD determinations conducted for the studied soil groups in various parts of the region. The obtained BD values differed for separate soil groups. Relatively high BD of mineral horizons was obtained for HsR, low BD - for AP. Larger BD of organic layer for HpR is explained by accumulation of comparatively well-decomposed organic matter on the soil surface. The BD of organic layers was comparable for AP and HsR. The SOC stocks in all soil groups were characterized by a wide variation with differences between minimal and maximal values changing from 4 to 13 times. A closer spread was for HpR. The highest SOC stocks in 1 m depth were calculated for HsR with the mean value of 12.66 +/- 0.13 kg m(-2). The SOC content in HpR was 7.69 +/- 0.12 kg m(-2) and in AP - 3.80 +/- 0.09 kg m(-2). The organic layer share varied from 24 to 35% in SOC stocks of the 1 m profile. The depth of 0-50 cm concentrates 70-78% of SOC of the 1 m soil profile. According to the mean SOC stocks data and the area of the soil groups we estimated SOC stocks concentrated in main soil groups in the Komi Republic.