Effects of Thinning Intensity on Aerial Seeding Pinus Tabulaeformis Stands
|School||Beijing Forestry University|
|Keywords||Chinese pine Aerial seeding forest Thinning intensity Comprehensive Evaluation|
Chinese pine is our warm temperate humid and semi- humid climate of the important tree species in northern China aerial seeding species . Explore the woodland quality control measures Pine aerial seeding Sustainable Management of Forest has important practical significance . 2000 in Beijing the Yanqing County wangjiapu aerial seeding afforestation base status level IV of the beginning of 1990 to create the Pine aerial seeding forest thinning intensity set 4 ( 30.00% , 48.75% , 53.75% , 77.13% ) processing and set a thinning ( CK ) stand as a control. In 2005, the situation by comparing the growth of trees , understory vegetation cover , diversity and biomass , soil physical and chemical properties , soil enzymes change , the use of PCA to explore the pros and cons of the thinning effect of understory vegetation, soil Comprehensive Evaluation . The results showed that , after thinning the stand , increase its growth indicators than thinning stands where thinning intensity of stand growth of 53.75% . The thinning intensity also affect the Pine aerial seeding forest community life form one of the factors . Thinning intensity , different dominant species of understory vegetation , shrub layer dominant species by China drought biological species to students replacement . With the thinning intensity increases, the understory vegetation species replacement rate is accelerated , the biomass increases . Pine aerial seeding understory vegetation diversity peaks between canopy density of 80 to 87% . Soil physical and chemical properties , in addition to the obvious response of the pH value to thinning intensity and other properties with the deepening of the soil layers decreases , the A layer thinning suffered the greatest impact . The five soils enzyme sensitivity to thinning different alkaline phosphatase by thinning the greatest impact , catalase , followed by the middle of urease , invertase , polyphenol oxidase impact minimum ; different levels of soil enzyme response to thinning A layer of soil enzyme activity changes the most obvious, with the increase of soil depth , enzyme activity convergence and reduced sensitivity to thinning . Different seasons, soil physical and chemical properties and enzyme activity in response to thinning . Combination of stand growth conditions , understory vegetation development status , the three indicators of soil fertility status , we arrive at the position level IV initial density 8000 · hm -2 sup > , 9 years old aerial seeding young Chinese pine trees select 48.75% thinning intensity .