Evaluation of organic carbon stocks in mineral and organic soils in Lithuania

Soil organic carbon (SOC) stocks at national level were estimated to provide more accurate estimates on SOC for the Lithuanian GHG inventory. The SOC stocks in the forest floor, grassland litter, and in mineral or organic topsoil (0-30 cm) of forest land, grasslands, and croplands were estimated. The assessment was based on forest floor and peat topsoil mass, mineral topsoil bulk density, and carbon concentration in 754 permanent observation plots on 9 x 9 km grid of the National Forest Inventory in Lithuania. The SOC stocks were obtained for eight WRB Reference Soil Groups to provide the estimates for land use, land-use change, and forestry reporting. The SOC stocks in the forest floor, topsoil of mineral, and peat layers were identified for soils under different land uses. The mean SOC concentrations in the 0-10 and 10-30 cm topsoil of most soil groups, especially fertile forest soils (Cambisols, Luvisols +Retisols) were higher for forest land and grasslands, and lower for croplands. The total averaged SOC stock in the forest floor in mineral and organic soils was 6.97 t ha(-1), whereas in the litter of grasslands it was 0.54 t ha(-1). The averaged SOC stock in topsoil varied from 56 t ha(-1) (Arenosols) to 118 t ha(-1) (Cambisols) in mineral forest soils and was 150 t ha(-1) (Histosols) in organic forest soils. The total averaged SOC stock in mineral topsoil of forest land, grassland, and cropland was 80, 74, and 72 t ha(-1), respectively.