Seasonal Changes in Soil Microbial Biomass Carbon and Nitrogen of Different Vegetation Types in the Mu Us Sandland, Northwestern China

The aim of the study is to determine the seasonal changes in sand soil microbial biomass carbon (C) and nitrogen (N) and to identify the pattern of sand soil microbial biomass of four vegetation types in the Mu Us Sandland in northwestern China. Four types of psammophyte plots were established in a desert botanical garden. Soil samples were collected at the depths of 0-10, 10-20 and 20-40 cm, before the 10^th of each month, from April to October 2015. The microbial biomass C (MBC) and microbial biomass N (MBN) concentrations were determined using chloroform fumigation extraction. The concentration of MBC did not show consistent patterns as the soil depth increased from 0-10 cm to 20-40 cm, although it was higher in the top layer than in the other layers in some stands (p<0.05). There was also a consistent pattern in different soil layers. All of the top layers showed similar changes from August to October. The MBN concentration in the middle layer was maximal in April, which experiences different types of vegetation, and was significantly higher in the Pinus sylvestris L. var. mongholica Litv and Salix cheilophila stands (p<0.05). Seasonal changes in desert soil MBC and MBN concentrations were obvious in the top soil layer. The peak MBC and MBN concentrations occurred during different seasons, with MBN higher during the colder months.