The variation feature of soil inorganic carbon storage in alpine grassland in Qinghai province

The warm steppe,alpine steppe,alpine meadow steppe and alpine meadow are the main grassland types which widely distribute in Qinghai-Tibetan plateau. It's widely distribution and diverse development environments make it play an important role in the ecosystem: supporting regional economic development,guaranteeing water conservation of the plateau,maintaining biodiversity,fixation of carbon,etc. A quantitative survey of the variation feature of soil inorganic carbon( SIC)stored in warm steppe,alpine steppe,alpine meadow steppe and alpine meadow were carried out in Qinghai province.Results showed that the total storage of SIC in the four types grassland appeared to be warm steppe alpine steppe meadow steppealpine meadow,and the values were 16. 51 kg C / m2,16.48 kg C /m2,3.37 kg C /m2 and 0. 12 kg C / m2,respectively.One-Way ANOVA analysis indicated that warm steppe、alpine steppe had a significant difference with alpine meadow steppe and alpine meadow( P 0. 05) while no significant difference between warm steppe and alpine steppe as well as alpine meadow steppe and alpine meadow( P0.05). The warm steppe and alpine steppe grassland are the main reserve pool of SIC in alpine grassland. The SIC stored in 50—100cm accounted separately for 60.2% and 51.8% of the total storage in 0—100cm profile of the warm steppe and alpine steppe,while in alpine meadow steppe and alpine meadow,it occupied 50.1%and 55.8% respectively of the 30—50cm in 0—50cm. Deep soil layer is the main place of SIC storing in alpine grassland.Soil depth has an important effect on SIC storage in alpine grassland. In 0—50cm depth of the soil,SIC storing in the four types grassland were 6.57 kg C / m2,7.95 kg C /m2,3.37 kg C/m2 and 0.12 kg C / m2,respectively. The change of SIC content with soil depth were different in the four types grassland. It increased with soil depth in warm steppe and alpine meadow steppe,but increased at first then decreased in alpine meadow steppe and alpine meadow. The calcium carbonate enrichment layer in the soil tallied with the foam examination by hydrochloric acid in the soil profile investigation. The calcium carbonate accumulate in the deep soil of steppe,but enrich rather shallow in meadow. SIC storage in the four types of grassland had a significantly positive correlation with soil bulk density and p H value but a significantly negative correlation with underground biomass. The SIC storage increased from south to north in the grassland of Qinghai province and the total SIC storage of the four types grassland reached 1.34 Pg in the profile. The SIC storage in the alpine meadow is very small and it mainly distributed in the south of Qinghai province. Warm steppe which has the largest SIC storage mainly distributed nearby the Qinghai Lake. Climate change and human activity may affect the capacity and distribution of the carbon storage which would bring the ecological risk to the inorganic carbon fixation.