The Characteristics Of Soil Carbon And Nitrogen And Nutrient Stock Of Different Forest Types In Northwest Of Sichuan

In this paper,we took 16 kinds of forest types in subalpine zone of Wolong Natural Reserve,mountain zone of Banruo Temple and Lingyan Mountain in northwest of Sichuan as research objects,analyzed soil carbon and nitrogen and total nutrient through sampling in soil profiles,in order to study the characteristics of soil carbon and nitrogen and nutrient stock of different forest types in northwest of Sichuan,to discuss the effects of different forest types on soil organic carbon and nutrient elements,to reveal the rules of soil carbon and nitrogen and nutrient in different soil depth and altitude height and to reveal the relation among the soil elements.The research results as follows:1,There was obvious difference of soil organic carbon reserves among different forest types.The reserves of subalpine dark coniferous forest,subalpine meadow,subalpine mixed forest and subalpine shrub were the most(190.9～264.8t·hm²).Subalpine deciduous broad-leaved forest and mountain evergreen broad-leaved forest were in the secondary level(62.1～208.8t·hm^-2).Plantations and mountain mixed forest were the least(81.1～159.2t·hm^-2).The soil organic carbon reserve was descending with the increase of soil depth and the range of decreasing in 0～40cm was the most,there was an obvious surface-abundance phenomena.Because of the effects of many microhabitats,the variation coefficients among sampling points under same forest type was high.2,There was obvious difference of soil labile organic carbon reserves among different forest types.The stock of subalpine picea coniferous forest was the most(105.5t·hm^-2). Secondly the subalpine shrub,subalpine meadow,mixed forest and deciduous broad-leaved forest(65.7～86.2t·hm^-2).Mountain evergreen broad-leaved forest and subalpine plantations were the least(33.2～55.9t·hm^-2).The soil labile organic carbon reserve was reducing with the increase of soil depth and the range of decreasing in 0～40cm was the most,there was an obvious surface-abundance phenomena.3,As the research results,besides there was huge influence from vegetation types to soil organic and labile organic carbon,there also was obvious difference between soil organic carbon stock and different altitude heights.It illuminated altitude was an important habitat factor to soil carbon reserves.Owing to the huge relative elevation in Wolong subalpine zone,the effect of altitude to soil carbon was prominent.The soil carbon of Banruo temple and Linyan mountain zone also had rules with the height ascending.4,Through accurate analyzing and sample surveying,we had the conclusion that there was enormous soil carbon reserves,fine quality of carbon stock and distinct storing ability under the forest types of 16 kinds from mountain to subalpine in northwest of Sichuan.It indicated there was great carbon sequestration potential of forest soil in northwest of Sichuan zone.5,There was obvious difference of soil nitrogen reserves among different forest types. The nitrogen content in subalpine zone was higher than mountain zone.Soil nitrogen reserves were descending with the increase of soil depth and the range of decreasing in low layers was small.6,There was obvious difference of soil nutrient stock among different forest types.Soil nutrient stocks of natural forest were higher than plantations.Mountain evergreen broad-leaved forest and subalpine plantation were the lowest.Linyan mountain zone had a big soil nutrient stock,fine nutrient status and was fit for planting fast-growth plantation.7,There were closely correlative relations among soil organic carbon,labile organic carbon,carbon potential management index(CPMI) and nitrogen.The distribution proportion of soil labile organic carbon were 29.49%～76.08%.The CPMI were 70.63%～2138.11%as the Taxodium distichum plantation for contrast and it could be regarded an important integrated index in soil carbon sequestration and soil quality estimating research in the future.The ratios between carbon and nitrogen were 6.89～13.80,and they were suitable for tree growth.