Influence of the Selective Intensity on Spatial Structure of Mid-subtropical Natural Mixed Stand of Conifer and Broad-leaved Trees

The spatial structure of mid-subtropical natural mixed stand of conifer and broad-leaved trees under different disturbances were analyzed by using 3 kind of structure parameters,which are mingling intensity,neighborhood comparison and uniform angle index.The experimental stands were harvested by selective cutting of different intensities(low intensity of 13.0% in volume,medium intensity of 29.1%,high intensity of 45.8%,over-high intensity of 67.1%) in November,1996.The un-cutting plots were set as controls.The result showed that the forest mingling intensity is the biggest in low selective cutting plots,that of medium intensity cutting ranks the secondary,while over-high intensity cutting plots exhibited aggregation of single species.Selective cutting intensity exerted little influence on diameter differentiation,but the positions of dominant species changed with different extents.Selective cutting did not change the spatial distribution of species.Aggregation distribution was the spatial pattern of either the forest as a whole or the dominant species,regardless of what selective cutting intensity is.The species was in clumped distribution in over-high selective cutting plots,while in non-uniform and random distribution in low and medium selective cutting.Generally speaking,the low and medium intensity selective cuttings may enhance the stability of forest community spatial structure effectively and its communities spatial structure is superior.