Soil and plant physicochemical property
Then the litter and root samples were used to determine C and N concentration, by using CHNOS Elementar Analyzer (Vario EL III, Elementar Inc., Hanau, Germany), and P concentration by using ultraviolet spectrophotometer (UV-2550, Shimadzu, Kyoto, Japan).
Soil samples were separated into 4 parts. One was air-dried and used to determine soil physicochemical property. Soil C and Soil N were determined by CHNOS Elementar Analyzer, soil available N was determined by using continuous flow analyzer (San++, Skalar, Breda, the Netherlands), Soil P and available P were determined by using ultraviolet spectrophotometer, pH was determined by a pH meter (FE20–FiveEasy), soil texture as reflected by the weight percentages of sand, silt and clay was determined by the hydrometer method (Ashworthet al. , 2001). The second part was freeze-dried and used to measure the phospholipid fatty acids (PLFAs), to represent the microbial community structure, including community total PLFAs and the components of bacteria, gram-positive bacteria, gram-negative bacteria, actinomycetes, fungi (Frostegård and Bååth, 1996). The ratios between these components were used to represent the relative composition of microbial community. The third part was stored at 4 oC and used to measure soil microbial biomass C, N and P, using chloroform fumigation extraction technique. The forth part was incubated in the lab to determine microbial respiration (MR) and its temperature sensitivity (Q 10).