Study on Ideal Stand Structure and Development of Spruce-Fir Mixed Stands in over Cutting Area in Changbai Mountains
|School||Beijing Forestry University|
|Keywords||natural spruce-fir mixed stands over cutting control method growth of volume ideal structure ideal development|
The paper has the natural spruce-fir mixed stands as the object of research, which is located in Jingouling forest farm, Wangqing forestry bureau, Jilin province. Based on the status of local forest management, it studies on ideal stand structure and growth dynamics of spruce-fir mixed stands in over cutting area in Changbai Mountains. The main contents are as follows:The objective of forest manament is determined. To natural commercial forest, it is to obtain the maximal volume growth on the condition of keeping stable stand structure.Using the datas of 1221 anatomical tree, the changing relation of tree diameter and age is analyzed, which changes with the growth of stand.The restoration and growth of stands are studied making use of 37 plots, including systemic sample plots and some others. On sampling, the precision exceeds 81%. The datas span 20 years, moreover, they are successive. The study goes on from the point of diameter structure, the proportion of different sized trees, species composition and volume structure, stabilization, thinning and so on. By contrast, the ideal stand structure can be fixed on.Referring to the selected ideal stand structure, the actual stands could be divided into several different growth stages, then analyze the characteristic of every stage.The research indicates new ideas as following. There is obvious positive correlativity between the diameter and the age. The actual age extent of a given diameter is almost the same as theoretic age. To natural spruce-fir mixed stands, the maximal growth of volume can achieve 11 m~3/(hm~2·A) to 15 m~3/(hm~2·A). They are mostly in the volume extent between 185 m~3/hm~2 to 330 m~3/hm~2. It is reasonable for species composition between 6:4 to 8:2. The density of trees is 800 n/hm~2～1400n/hm~2. The period between two close harvests is 6 to 10 years, with a thinning proportion of 10% to 20%. The whole process of forest development can be divided into 6 stages. They have their own particular stand structures and characteristics, and together form a integral forest succession. The 20 years test of management in control method has adjusted and improved stand structure of spruce-fir mixed stands. It has promoted the forest ecosystem to a positive succession.