Soil Basic Characteristic And Carbon Nitrogen Transformation In Quercus Variabilis Secondary Forest Of Different Regions

Soil carbon and nitrogen pools are the important part of the natural ecological system,and the influence factors include temperature,moisture,soil parent material,microbes,vegetation,land use,etc.;Due to the complicated influence factors,interactions and feedback mechanisms,a lot of research showed different results,therefore it is necessary to study on the relationship of soil basic characteristics and carbon and nitrogen transformation ability around different latitude area.This research focused on Quercus variabilis forest ecological system with widely distribution on regional scale,including the warm temperate zone?Beijing and Xingtai?,transition of warm temperate and subtropical zone?Xinyang and Xiaoxian?,subtropical zone?Huangshan and Yongxiu?.The reserach focused on basic features of soil and litter decomposition and microbial transformation process of forest ecology system,discussing the effects on soil carbon pool with the change of the regional environmental elements of quercus variabilis secondary forest.According to the Forest soil Analysis Method,the main types of soil were loam and clay loam classes;Soil density was 0.93¹.26 Mg·m^-3;Total porosity was 45⁵6%;pH value of Quercus variabilis secondary forest soil was from strong acid to weak alkaline,as the characteristics of"acid to alkali from south to north";Available P content was 5¹5 mg·kg^-1;Available K content was 50²00 mg·kg^-1;Regional soil physical and chemical properties showed different significantly,and the soils were loose with low fertility in general.Soil microbial biomass carbon content was270⁷50 mg·kg^-1;Soil net mineralization rate of nitrate nitrogen was1.0¹.5 mg·kg^-1·d^-1;Oe and Oa layers'carbon contents were 200⁴00,100²00 g·kg^-1 with the nitrogen contents of 10¹6,8¹1 g·kg^-1,respectively;With the increase of soil depth,carbon and nitrogen contents decreased significantly,0²,2⁵,5¹0,10²0 cm depth layer of soil carbon content were in the order of 30⁷0,15⁴5,10³5,5²5 g·kg^-1,the readily oxidizable carbon?ROC?contents of 17⁴1,9²3,6¹8,5¹5g·kg^-1,the nitrogen contents of 2.8⁴.5,1.8³.1,1.4².6,0.8².1 g·kg^-1;Especially,soil from Yongxiu had the largest and most stable carbon and nitrogen pool,while the soil from Xiaoxian had the smallest carbon and nitrogen pool,and soil from Xingtai had most unstable carbon pool,and soil from Huangshan had most active microorganisms.Readily oxidizable carbon?ROC?content of litter and soil were of high consistency with carbon content,and their relation could be described as the regression equation:Y=0.581·X-6.131?R²=0.893,p<0.01;Y:litter ROC content;X:litter carbon content?;Y=0.609·X-0.714?R2=0.978,p<0.01;Y:soil ROC content;X:soil carbon content?;Readily oxidizable carbon,carbon and nitrogen content were significantly positive correlation,and could described as linear regression model,respectively:Y=3.76·X-4.96?R2=0.905,p<0.01;Y:soil carbon content;X:soil nitrogen content?;Y=8.44·X-3.87?R2=0.898,p<0.01;Y:soil ROC content;X:soil nitrogen content?.The research showed that where in the same climate condition,the soil with high content of clay particles had larger and more stable carbon pool with uniform distribution of carbon and nitrogen;While soil with high content of sand particles had larger aeration porosity and higher microbial biomass in order that the organic matter was mineralized faster,and soil carbon,nitrogen content were harder to accumulated,as the result of small and unstable carbon pool.The effect of microorganisms was more apparent in south soil.This article verified the protection of the organic matter by clay under different climate,the relationship between microbial mineralization,climate,soil texture and air permeability.