| Larix princicpis-rupprechtii Mayr. is representative of the special forest trees at the warm temperate zone sub-alpine areas in our country. Because of strong adaptability, fast growth, trunk shape well and quickly volume growth, it become more and more wide application. Larix princicpis-rupprechtii Mayr. artificial forest play an important role in water conservation, windbreak and sand-fixation as well as the formation and maintenance of ecological system in northern hebei, but for single tree species, multiple plant and poor management, seriously influence the growth of trees. This paper was based on the different thinning intensity and prune measures of Larix princicpis-rupprechtii Mayr. and taking different treatments to pruning residuum, to survey and analyze the plant growth, canopy structure, soil physicochemical properties and biodiversity etc. various elements. A comprehensive analysis on the effect of different thinning measure, is to determine the reasonable management density and specific tending measure of Larix princicpis-rupprechtii Mayr. artificial forest to provide the basic theory. The main conclusions are as follows:Firstly, through analyzing to the different thinning intensity, prune intensity and different treatments to pruning residuum of Larix pricipis-rupprechtii Mayr., we can see that the stand growth environment influence on light and soil porosity (reflecting the supply capacity of water) were more closely, and show certain regularity. By the analysis, the following conclusions are given:(1) LAI and the canopy coverage change rule basic same after thinning or pruning with different strength, are shown as: Along with the thinning or prune the index increased.and growth variation alternate size. But overall, LAI of thinning which most strength changes to a larger extent, and the moderate pruning is a higher change. Moderate thinning (2400 strains/hm~2) and the most strength pruning (forest crown high percentage 3/5) are conducive to the growth of the canopy, and pruning is more advantageous to the growth of canopy than thinning.(2) The soil porosity and soil bulk density after different strength thinning or pruning assume that with increasing of strength, all improving the soil porosity of thinning or pruning, but the soil bulk density and soil porosity has inverse correlation.(3) Soil nutrient elements content of thinning and pruning with different strength and the different treatment of using pruning are not exist significant differences. 2 The capillary porosity and bulk density of the soil has the extremely remarkable correlation, The total soil porosity and soil non-capillary porosity is significantly related. The light,the soil porosity and soil nutrient elements affecting understory diversity together, It can determine, the main factors of The understory diversity in the short-term effects is light (canopy coverage degrees, LAI), water(soil water content).3 Based on the Thinning or pruning with different strength. and the different treatment of using pruning, though survey and the relevant analysis on growth, the main results are as follows:(1) the results that: diameter growth rate increased with increasing thinningintensity rules were as follows: heavy thinning(1800strains/hm~2) >moderate thinning(2400 strains/hm~2) > weak thinning(3000strains/hm~2) > control(3600strains/hm~2), and significantly higher than the control standards to DBH growth rate after thinning stands, indicating that the appropriate intensity of thinning is conducive to the growth of DBH. Tree height growth rate trends with the DBH growth rate similar to, but there is no significant difference between the thinning stand, only with the control area, there are significant differences. The results showed that the intensity of thinning and moderate thinning diameter at breast height and tree height growth rate increased, therefore thinning to retain 1800-2400 strains/hm~2 is appropriate.(2)The test set respectively is: pruning strength set based on the crown height percentage respectively is 4/5,7/10,3/5 and set control area; pruning remains set respectively is placing, cleaning, crushing and set control area. Result showed that: Different levels of pruning of forest trees at DBH growth rate all have certain improvements, among them, moderate pruning of forest trees DBH,promotion height rate of growth and the tree Canopy coverage index increase is obvious; according to different treatment of the test pruning remains early results show that, crushing and clean up processing stand is helpful for the improvement of forest tree DBH rate, crushing stand is more conducive to improving forest tree height growth rate.(3)The test showed that pruning is conducive to the growth, but results show that : the different treatment of pruning residues , and the decomposition conversion effect not adequately do not have a more fully convincing due to the shorter term. after pulverization treatment, and cleaning up the stands, conducive to the growth rate of DBH. Thus treated stands are more conducive to high growth rate of forest tree.The test showed that pruning is conducive to the growth.4 Through the correlation analysis of the indicators: thinning of different intensity than the different intensity of pruning is more conducive to the improvement of the DBH growth rate, pruning with different strength is more conducive to the growth of tree height. |
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