Effects of enclosure period on carbon and nitrogen characteristics and components of soil organic carbon in Artemisia desert

In order to explore the response of soil organic carbon components to enclosure in rangeland, the soil particulate organic carbon (POC), particulate organic nitrogen (PON), light fraction organic carbon (LFOC), light fraction organic nitrogen (LFON), microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) of Seriphidium transiliense desert after different enclosure years(including 0 year, 1 years, 6 years and 9 years)were studied. The results showed that the POC, PON, LFOC and LFON contents in soil layer of 0-5 and 5-10 cm in S. transiliense desert firstly decreased then increased with the increase of enclosure years which reached minimum after 6-year enclosure. Only POC, PON, LFOC and LFON contents in 0-5 cm soil layer after 6-year enclosure were significantly lower than those of the control (0 year) and after 9 year enclosure. Except with that LFOC contents in 10-20 cm, 30-50 cm soil layers and LFON content in 30-50 cm soil layer after 6-year enclosure were significantly lower than those after 1 year enclosure, there was no significantly difference between different enclosure years for POC, PON, LFOC, LFON contents in 10-50 cm soil. The MBC and MBN contents in 0-30 cm soil firstly decreased then increased with the increase of enclosure years which reached minimum after 1 year enclosure. Except with MBC content in 5-10 cm soil layers, all other indices were significantly lower than those after 9 years enclosure. There was significantly positive correlation among POC, PON, LFOC, LFON, MBC and MBN, especially PON could more accurately reflect the soil quality changes. In conclusion, carbon and nitrogen content of soil organic carbon components in 0-5 cm soil were more sensitive to enclosure and the soil microbial biomass carbon and nitrogen response more quickly.