Study On Two Kinds Of Soil Acyive Carbon Under Platycladus Orientalis Plantation In Imestone Mountain In Xu Zhou

In this study, the characteristics and the seasonal variation of the two kinds of soil active carbon were systemtically studied by sampling analysis and laboratory testing under 3 different typical vegetation communites and 4 density gradient forest stand in the Limestone mountain in Xuzhuou, our results showed that:(1)The amount of the soil microbial biomass carbon(SMBC) and water soluble organic carbon(WSOC) both increased along with the transforming from grassland to forestland. Among the transformation, the variation tendency of SMBC under different vegetation communites was: MBF(mixed broadleaf-conifer forest)>DBF (Deciduous broadleaf forest)>CF(Coniferous forest)> C(Bush-grass land); the variation tendency of WSOC under different vegetation communites was:DBF (Deciduous broadleaf forest)> MBF(mixed broadleaf-conifer forest) > CF(Coniferous forest)> C(control);(2)Classify Platycladus orientalis of different plantation stand density by density into four density gradient:the high-density gradient stand (stand density greater than 1500 trees/ha),middle density gradient stand (stand density of 1000-1500 trees/ha,low density gradient stand (forest density 500-1000 trees/ha),Scattered grassland (stand density less than 500 trees/ha), respectively. The result show that; the variation tendency of SMBC and WSOC under disfferent density gradient was:Middle density stand>High density stand> Low density stand> Scattered grassland.(3)Two kinds of Soil active carbon has significant seasonal variation, our result of the study demonstrate that: the characteristics of seasonal variation of the SMBC under the different vegetation and density gradient is that the peak vaule of soil active carbon appeared in summer, the valley appeared in winter, on the conctrary, the characteristics of seasonal variation of the WSOC is that the peak vaule of soil active carbon appeared in winter, the valley appeared in summer.