Study On Spatial Structure Optimizing For Natural Secondary Forest In Maoershan

This study utilized 30 permanent sample plots analysis trees in Mao'er Mountain experimental secondary forest area, Several spatial structure indices were dealed with and according to diversity mingling, aggregation index, competition index and crown area overlap index, a spatial structure optimizing model of secondary forest stand selective thinning was developed which can be solved by mathematic programming and apllied to the realistic stand. The primary works are below:(1) Based on the theoretics of multiply divide, the spatial strcture optimizing model of secondary forest stand selective thinning was developed by diversity mingling, aggregation index, competition index and crown area overlap index, also designed 10 constraint conditions which were related to forestry meanings, the objective function was solved by the implicit enumeration method with LINGO 9. 0, using 0-1 integer programming.(2)The model took M702 sample plot as an application example to specific every felled trees, and the value of objective function was changed quite significant which was increased more than 5 times after selective thinning, these proved that it satisfied the requirement of model design. Diameter class, species remained their steadiness while Shannon-Weiner index increased 3. 5%. The value of q in constraint conditions decreased 6. 6%, as the competition index and crown area overlap index decreased 19.99% and 50. 93% respectively, howerver, the diversity mingling and aggregation index increased 2. 5% and 4.1% respectively. The yield from felling less than the increment of stand and the volume decreased 27. 03%. 10 constraint conditions were all satisfied after the objective function solved which value increased obviously, these result reached the model design requirement as well as accorded with forestry meanings.(3) This study calculated the Maoershan 30 areas of natural secondary forest logging standards of strength, harvesting intensity ranged from 20% -30%, and harvesting intensity is the minimum value 19.44, the maximum is 29.03. After structural optimization, the tree is no longer between the crowded, crown overlay to improve the situation, the translucent canopy increased, a more reasonable structure and stability. This relatively high intensity of harvesting the design is conducive to the improvement of the spatial structure.(4) The Institute Maoershan investigation of secondary forest is divided into 4 types: Mongolian oak forest, Birch forest, broad-leaved forest and the trees hard. Harvesting intensity are as follows: Quercus mongolica forest harvesting intensity of 22.33%, Yang Hua Lin logging intensity 19.44% -26.31%, and hardware intensity of broad-leaved forest logging for 22.73% -29.03%, and forests for logging intensity 20.87% -27.48 between.