Study On The Change Of Soil Carbon Pool And Its Influencing Factors In Dabie Mountain Area

The soil carbon pool is divided into organic carbon and inorganic carbon pool.It is of great significance to study the reserves of soil carbon pool for understanding global climate change,land degradation and soil quality evaluation.According to the data of 1:250000 target geochemical survey,we estimated the reserve of organic carbon and inorganic carbon pool in the soil of Huoshan and Jinzhai County,and analyzed the distribution characteristics of carbon density and its influencing factors in this dissertation.By comparing with the data of second national soil surveys,the changes of topsoil carbon over the last 30 years of the study area were estimated,and soil CO₂ efflux was observed to understand better the variation process of soil carbon and carbon sink effect,which consequently aims to provide a theoretical basis for assessment of soil carbon sequestration potential and adaption measurements of global change.The main results are as follows:1.The surface,middle and deep organic carbon reserves of the study area were 9.54 Mt,36.44 Mt and 56.55 Mt respectively,and 64%of the organic carbon in the study area was stored in the soil above 1m.The inorganic carbon reserves of each layer are 0.8 Mt,4.02 Mt and 6.97Mt respectively.The organic carbon density and inorganic carbon density in the study area were larger than those of the Taiyang Township,the southwest of Tiantangzhai Town and the western part of Zhangfan Township.The organic carbon density and inorganic carbon density are relatively low in the southern part of Qingshan Town-Yanzihe Town-Shangtushi Town,and Taipingfan Township-Bailianyan Township,and Dongxixi Township.Soil types of high organic carbon and inorganic carbon density are purple soil and brown soil,but crude bone soil,yellow brown soil and paddy soil for low density;For different land use type,the organic carbon density and inorganic carbon density are high in woodland and paddy field but low in tea fields and dry land;Both the organic and inorganic carbon density under different terrains rank from high to low as:central mountainous Region>low mountain Region>plain.2.The study area is overall carbon source area,and the organic carbon density is decreasing.The density of surface organic carbon decreased by about 1.7 kg/m² on average compared with the second soil survey period,and the carbon stocks decreased by 5.25 Mt,with an average decrease of 36%and an average annual decrease of 0.06 kg/m².3.The SOC content was significantly negatively correlated with the soil pH value,slope direction,and H<400 m?P<0.01?.It is positively correlated with N,S,slope,H?400 m?P<0.01?;No correlation with P?P>0.05?.There was no significant correlation between the content of SIC and the elevation of soil pH,W,P and H<400 m?P>0.05?;There is a significant positive correlation with SOC,N,S,slope and H?400 m?P<0.01?.4.The CO₂ respiration rate in the study area ranges from 0.01⁴8.88 g/m²/d,with an average of 10.19 g/m²/d,and the annual emission of CO₂ in the whole study area is 11.52 Mt,accounting for 18.13%of the soil carbon storage in the study area.The soil types with higher respiratory rate were purple soil and yellow brown soil,and the lower ones had brown soil,coarse bone soil and paddy soil.The types of land use with high respiration rate are:bamboo forest and shrubbery,and the lower ones have tea fields,dry land and paddy fields;In terms of geomorphic type,CO₂ respiration rate is characterized as:low mountain Region>plain>central mountainous Region.