Study On Mixed Structure Of Two Forest Type Of Jingouling Forestry Station

This paper has the spruce-fir mixed stands, polar-birch secondary forest as the object of the research, which is located in Jingouling forestry station, Wangqing forestry bureau, Jilin province. The mixed structure, change tendence of soil nutrients and biodiversity of two forest types with different conifer-broadleaf ratio,and content of chemical element in leaf of the main species have been researched. Aiming to put forward the optimal species composition for the two forest types.This paper analyzes the difference and change tendence of soil nutrients between different conifer-broadleaf ratio of Spruce-fir mixed stands and Polar-birch secondary forest. The soil sample of 7 types of Spruce-fir mixed stands and 4 types of Polar-birch secondary stands have been test. The soil nutrients indexes include:soil organic matter, total N, total P, total K, available N, available P, available K and pH. The fuzzy linear membership function was used to dimensionless all nutrient indexes. Using principal component analysis to determine the index weight, then calculate comprehensive index of soil nutrient.To analyzes the relationship between different conifer-broadleaf ratio and biodiversity, we calculate the Gleason index%Shannon index、Simpson index and Pielou index. The main conclusion are listed as follow.(1) There are a total of 31 species in the two forest type. These species belong to 16 families and 28 genera. The ratio between pioneer trees and top trees in Spruce-fir mixed stands is 4:6, and it is 4:6 in Polar-birch secondary stands; The conifer-broadleaf ratio is 4:6 in Spruce-fir mixed stands, and it is 6:4 in Polar-birch secondary stands. The top trees in Spruce-fir mixed stands is more than Polar-birch secondary by 51%. It means that the Spruce-fir mixed stands is the advanced stage during the process of community succession.(2) The soil of two types of forest is acidic, and with the increase of proportion of hardwood, stand s pH increases, it means that soil become acid. The soil pH of spruce-fir mixed stands is between 4.70 and 5.02. The soil pH of polar-birch secondary stands is between 5.56 and 5.80. (3)The result shows that there is a significant correlation between soil nutrient and conifer-broadleaf ratio of Spruce-fir mixed stands and polar-birch secondary stands; the increase of conifer species is conducive to the accumulation of the N and P in the soil; Organic matter is the basis of soil fertility, and the main source of soil N, P, K;When the conifer-broadleaf ratio is 7:3,the spruce-fir mixed stands contain the most Organic matter, with 7.10%. The polar-birch secondary stands is 3:7,with 5.39%.(4)A11 stands of two forest types show good in soil nutrients; the comprehensive soil nutrient content is the highest when the ratio is 7:3.The comprehensive soil nutrients of spruce-fir mixed stands is higher than polar-birch secondary stands, matches with the succession rule. For spruce-fir mixed stands, when the conifer-broadleaf ratio is 7:3,for polar-birch secondary stands, when the conifer-broadleaf ratio is 3:7,the comprehensive soil nutrients is the highest.(5)There are a total of 56 species, herb 37,shrub 19; through investigation of spruce-fir mixed stands; and a total of 43 species, herb 28,shrub 15 through investigation of polar-birch secondary stands. The biodiversity of polar-birch secondary stands is 23% less than spruce-fir mixed stands. Result shows that in the process of community positive succession, species number and variety are growing.(6) For spruce-fir mixed stands, when the conifer-broadleaf ratio is 7:3,for polar-birch secondary stands, when the conifer-broadleaf ratio is 3:7,the community species diversity is the largest, it means the mixed ratio mentioned above is conducive to maintaining high level of species richness.(7) The order of content of chemical element in leaf of the main speciesis is N> P> K, and the shrub is higher than arbor. The variation of K is the least outstanding, and P is the most outstanding. The content of chemical element in leaf of Tilia tuan Szyszyl.is the most than other trees, it means that it’s ability of return nutrient to soil is better than others.