Stand Structure Analysis Of Natural Mixed Spruce-Fir Forests In Changbai Mountains

The natural spruce-fir forest is widely distributed in Changbai Mountains.lt is dominant forest type in the region and have relatively high forest productivity and stability.The primary spruce-fir forest and secondary spruce-fir forest were studied by diameter class diversity indices with the three spatial structure indexes of mingling, neighborhood comparison and neighborhood pattern in the changbai mountains to provide a theoretical basis for the scientific management of natural mixed spruce-fir forests in Changbai Mountains.There are mainly research results:The results showed that diameter class diversity had not too much change for the primary spruce-fir forest in the25years,but first increased and then tended to decrease in small scale.The study for the present stand spatial structure showed that the average mingling in the stand was0.82,showing that the stand had a larger mixed degree,the stand was in a stable level.The values of neighborhood comparison of diameter at breast heigh and tree height for the stand was0.50and0.46respectively,overall dominance had the potential to continue to rise.The average value of neighborhood pattern of the stand was0.514,showing a random distribution.Stand spatial structure and diameter class diversity of natural mixed spruce-fir secondary forests in Changbai mountains was investigated, after initial selective cutting with different intensity(not selective cutting,20%,30%,40%), The results showed that diameter class diversity of the plots in the cutting intensity of20%was higher than the other plots. The average mingling intensity of the plots in the cutting intensity of20%was the biggest,the cutting intensity of30%ranks the secondary, while the cutting intensity of40%is the least. Selective cutting intensity exerted little influence on diameter differentiation,The species was in uniform distribution in the plots with cutting intensity of20%,The species was in random distribution in the plots with cutting intensity of30%and in no selective cutting plots,while in round state distribution in the plots with cutting intensity of40%.Generally speaking, the cutting intensity of20%may enhance the stability of forest community spatial structure effectively and its communities spatial structure is superior.