Elevated CO2 affects the content of glomalin related soil protein in xeric temperate loess and temperate semi-desert sand grasslands

Monoliths of temperate loess grassland and temperate semi-desert sand grassland have been exposed to elevated CO2 (700 μmol mol-1) and present ambient CO2 concentration in a 6-year open top chamber (OTC) experiment. In loess grassland elevated CO2 increased both biomass and vegetation cover, whereas there was no similar effect found in semi-desert grassland. The content of glomalin related soil protein (GRSP) increased in both loess and sand grasslands under CO2 enrichment (early summer aspect). The increase was higher in the case of easily extractable fraction (EEG), representing 14.7 and 22.2% of the chambered control’s EEG, for loess and sand grassland respectively. In the case of total glomalin the increase was much lower 7.9% (loess) and 2.6% (sand). On the basis of differences between elevated and ambient CO2 treatment we could conclude that elevated CO2 promoted C-deposition in xeric temperate grassland in early summer. Increases of EEG indicate an efficient partitioning of the recently fixed carbon to the soil.