Elevated CO2affects the content of glomalin related soil protein in xeric temperate loess and temperate semi-desert sand grasslands

Abstract

Monoliths of temperate loess grassland and temperate semi-desert sand grassland have been exposed to elevated CO 2 (700 μmol mol −1 ) and present ambient CO 2 concentration in a 6-year open top chamber (OTC) experiment. In loess grassland elevated CO 2 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 CO 2 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 CO 2 treatment we could conclude that elevated CO 2 promoted C-deposition in xeric temperate grassland in early summer. Increases of EEG indicate an efficient partitioning of the recently fix...