Research On Intermediate Cutting Index Of Natural Secondary Forest

Natural secondary forest is a kind of forest stands that restored through natural regeneration or artificially induced natural regeneration from a wildwood of which remarkable changes happen to the structure, species composition or basic function because of human destructive interference or abnormal natural disturbance. It is very important reserve forest resource. Trees in current natural secondary forests on the whole grow recession prematurely, bad shaped, and produce woods in poor quanlity, and species composition of these forest stands is not quite ideal. It is urgent to take scientific and appropriate cultivation and management measures to establish reasonable and stable structures or natural secondary forest communities and improve their productivity.The paper is a part of the public welfare industry of the state forestry administration research projects:"Southern collective secondary forest tending and thinning and efficient use of technology research (The Item Number:201004032)" and natural sciences foundation of China:"Research on spatial method of Dongting Lake wetland forest ecosystem management(The Item Number:31070568)". Intermediate cutting is the most important step in the process of forest cultivation. For natural secondary forests, the core issue of intermediate cutting is how to choose trees that to be cut. This determines the cultivation direction and nurturing quality of a natural secondary forest. In traditional intermediate cutting, trees are being classified to choose the ones that to be cut. The concept of Intermediate Cutting Index has been come up with to quantize the possibility of a tree being chosen to cut in the process of intermediate cutting. The main results are as follows:1. A tree’s intermediate cutting index means the possibility of the tree being chosen to cut in the process of intermediate cutting. The value of a intermediate cutting index is between0to1. The bigger the value is, the higher the possibility is.2. Six indexes (degree of freedom, mingling, neighborhood comparison, health index, spatial density and aim index) are chosen to construct intermediate cutting index. Using AHP to get weight coefficients for the six indexes according to types of the objective stands, then we can get the value of intermediate cutting index for a tree combined with its values of the six indexes.3. The order of importance of the six indexes for natural secondary forest is health index(0.295), aim index(0.290), spatial density(0.202), mingling(0.096), neighborhood comparison(0.069) and degree of freedom(0.048).4. Four test plots have been set in four kinds of natural secondary forest stands, they are Cyclobalanopsis myrsinaefolia mixed forest, Schima superba mixed forest, Choerospondias axillaris and Cunninghamia lanceolata mixed forest and Sassafras tzumu mixed forest. Schemes of choosing trees to be cut during the intermediate cutting have been drawn up through calculating intermediate cutting indexes under a given intensity. The results proved that it can get scientific and reasonable decision-making schemes of choosing trees to be cut during the intermediate cutting by calculating intermediate cutting indexes of trees for a forest stand, and it can primely meet our expected demands for intermediate cutting.