Evaluation of soil organic carbon stability in grasslands of protected areas and arable lands applying chemo-destructive fractionation
The soils of Natura 2000 protected areas (Endocalcari-Endohypergleyic Cambisols, Fluvi-Eutric Fluvisol and Endohypogleyi-Eutric Fluvisols) and agrarian lands overgrown with grasses (Endocalcari-Endohypogleyic Cambisols) were investigated in this research in 2012. The soil organic carbon (SOC) concentrations decreased with the depth in all treatments, and the highest values were measured at 0-10 cm soil layer in pre-mainland section of middle reaches of the Nevėžis (76.8 g kg -1 ) and in old
... -1 ) and in old semi-natural pasture (49.5 g kg -1 ). The exclusive importance of the agrarian soil occupied with grasslands and long-lived swards and soils of protected areas occupied with natural meadows for environmental quality was revealed, because organic carbon was accumulated and sequestrated in the form of stable compounds. Natural encroachment of wood pasture by forest plant communities in the northern part of Klamputė wood pasture significantly increased SOC. The content of SOC was higher in all soil layers in wood pasture under restoration compared with surviving wood pasture. The carbon transformation processes in wood pastures differed depending on the depth: organic carbon was more stabilized in the 10-20 and 20-30 cm layers in the surviving wood pasture than that in wood pasture under restoration. It was established that the most intensive transformation and accumulation of organic carbon take place at 0-10 cm soil layer. The soils of protected areas and agricultural lands were characterized by differences in organic carbon stability. After applying the method of chemo-destructive fractionation the largest amount of residual organic carbon, which represents the resistance to degradation and the possibility to sequestration, was established in the soils under long-term use of grassland (pre-mainland section and old semi-natural pasture). The most unfavourable status of SOC, and thus all the soil organic matter (SOM), is observed in the riverside section. The labile carbon was dominant there, and the content of organic carbon resistant to chemo-destruction was very low in all soil layers.