Dynamics of soil organic carbon in the steppes of Russia and Kazakhstan under past and future climate and land use

Abstract Changes in land use and climate are the main drivers of change soil organic matter contents. We investigated impact largest policy-induced conversion to arable land, Virgin Lands Campaign (VLC), from 1954 1963, massive cropland abandonment after 1990 on carbon (SOC) stocks steppes Russia Kazakhstan. simulated budgets pre-VLC period (1900) until 2100 using a dynamic vegetation model assess impacts observed land-use as well future scenarios. The simulations suggest for entire VLC region (266 million hectares) that historic expansion resulted emissions 1.6? 10 15 g (= 1.6 Pg) between 1950 1965 compared 0.6 Pg scenario without expansion. From 2100, alone is projected cause about 1.8 (± 1.1) carbon. Hypothetical recultivation has been abandoned fall Soviet Union 2050 may 3.5 0.9) whereas all would lead sequestration 1.2) For scenarios based SRES (Special Report Emission Scenarios) emission pathways, SOC declined only moderately constant but substantially with further variation response was smaller than This suggests effects dynamics become relevant those Eurasian steppes.