The aim of the study: to determine and compare the pools of organic carbon in the plants and sandy soils (Arenosols) in the Scots pine plantations and abandoned arable land.

The object of the study: the experiment was established in 46-year-old Scots pine plantations growing on Arenosols in Perloja experimental station of Lithuanian Agricultural Institute, and the abandoned 12 years ago arable land.

Methods: The stocks of organic carbon in the plants, roots and forest litter were calculated by multiplying the biomass of different compartments (t ha-1) with the carbon concentrations (g kg-1), and later the values were reduced by 1000 times. The pools of organic carbon in the mineral soil were calculated as follows: first, the density (g cm-3) of fine soil (<2 mm) was measured; and then it was multiplied with the concentration (g kg-1) of organic carbon and the depth of mineral soil layer (m); later, this value was increased by 10 times.

The results: the content of organic carbon was estimated and compared in the above-ground biomass and roots and in the organic and mineral horizons of the Arenosols in the Scots pine plantations and abandoned arable land. The soil respiration (CO2 emitting) from the different biotopes was also measured and compared.

It was determined that total C storage in the plants and Arenosols amounted 173.1–212.1 t ha-1 in Scots pine plantations, and it was by 4.7 times higher than in abandoned arable land (31.4–49.6 t ha-1). It could explained by C sequestration in above-ground biomass of pine tree, and by 12-14 times higher C pools in forest litter (23 t ha-1) and roots (28 t ha-1) of Scots pine plantations to compare with these pools in abandoned arable land as well. However, there were no statistically significant differences in CO2 respiration in studied biotopes.

Raktažodžiai: Perloja experiment, Scots pine plantations, abandoned arable land, organic carbon, soil respiration