Characteristic Of Soil Organic Carbon Of Typical Forest In Taihang Mountains’ Southern Foot Forest

The soil carbon pool is an important part of the earth ecosystem carbon pool, the soil carbon pool in forest ecosystem is accounting for about 73% of global soil carbon stock. It can change CO2 concentration of the atmosphere, and then triggering global climate change. It is subjects worthy research that soil organic carbon forest distribution and change characteristic during forest growth and the influencing factors of soil organic carbon accumulation.This study selected the typical forest types in south Taihang Mountain foot, and the soil carbon characteristics and influence factors of typical forest types was studied and analysis with The typical sample survey method and laboratory analysis measuring method.The purpose of this research was to reveal the spatial and temporal characteristics, variation and influencing factors, and provided the data and reference for forest soil carbon pool estimates and the forest sustainable management of this region. The major conclusions were summarized as follows:(1) Six forest types including non-forest land (bare land and grass land), shrub forest(ZipHusjujuba var and Vitex negundo L var), arbor forest(20a Platycladus orientalis,20a Robinia pseudoacacia,20a Quercus variabilis and 40a Quercus variabilis) in different forest growth stage were selected to study the soil variation characteristics. The result showed that the physical and chemical property were different and the physical and chemical property of large forest age were obviously improved. The soil profile survey showed of typical forest that the soil physical property has the obvious regularity with the soil depth. The chemical nutrients(N,P and K) of different forest growth stage had the apparent surface-aggregation. The soil TN of 40a Quercus variabilis was increasing 3.36 and 2.52 times than the bare land and grassland. The NH4+-N and NO3--N content showed the same variability. The soil TP and TK content did not change in the non-forest land because of parent materials of soil and increased slowly in plantations. The variation of surface layer soil rapidly available P and K were more obvious. At the same time, the soil physical and chemical property changed weakened with the soil depth.(2)In this study, the litter amount increased with the forest growth in different shrubs and plantation. The soil organic carbon, dissolved organic carbon and microbial biomass carbon showed increasing gradually with the affection of both litter accumulation and root development. The soil organic carbon and component in surface layer were highest and decreased with increase of soil depth, the soil organic carbon and its compositions of 40a forest of Quercus variabilis were higher than 20a arbor forest, shrub forest land and non-forest land.. The seasonal variation of soil organic carbon and component showed regularities in the affection of atmospheric temperature and humidity and seasonal precipitation. The content of soil organic carbon and dissolved organic carbon were high in summer and autumn and lowest in winter. The microbial biomass carbon fluctuated obviously in four seasons, apart from the peak appeared in autumn, the peak of microbial biomass carbon appeared in summer in the others, and the lowest of microbial biomass carbon appeared in winter in all.(3)There was a positively correlated (P<0.005) between soil organic carbon and soil water content rate, soil porosity in soil profile layers of typical forests. The soil bulk appeared the negative correlated with soil organic carbon. The soil pH showed the weakly alkaline and a negative correlated between soil organic carbon but with limited impact on soil organic carbon. There were significant positive correlation between soil organic carbon and TN, NH4+-N of different forest types, but the poor correlated between soil organic carbon and NO3--N because of the characteristics of leaching. The soil C/N of different forest types were less than 25:1 with no significant variation. The relationship between soil C and N showed highly dependence with a certain proportion. There were positive linear correlated between soil organic carbon and soil P, K in different forest types, and it showed that the variation of nutrients have influence on accumulation of soil organic carbon. There were positive linear correlated between litter and SOC, DOC and MBC. The analysis results on relationship between SOC and the soil factors showed that the coupling relationship were complex and indirect.(4) The soil organic carbon density has greatly improved with forest age growth in south foot of Taihang Mountain, and the soil organic carbon density of non-forest range:5.53～8.74t · hm-2, the soil organic carbon density of shrub forest range were 26.73-29.89 t · hm-2, the soil organic carbon density of arbor forest range were 27.53-36.29 t · hm-2. The soil physical and chemical properties, nutrient content, SOC and its components of 40a forest of Quercus variabilis were significantly better than 20a arbor forest, shrub forest and non-forest, but the advantage reduced with the soil depth.Above all, the soil characteristics and soil organic carbon distribution appeared obvious difference by the affection of forest structure, forest age, soil characteristics and forest litter of forest growth stages in Taihang Mountain southern foot, And the development of forest promote the accumulation of soil organic carbon.