Effects Of Tending And Thinning On Spatial Structure And Competitive Growth Of Larix Principis-rupprechtii Forests

Based on close Guandi mountain forest region is set to two different types of samples,and carries on the investigation and study,with the results of the study demonstrates the progressive type three problems: the thinning of the stand spatial structure under the influence of the change,and the thinning of adjustment of plantation forest competition relations change,thinning slow-release target tree growth response of target tree after pressure.The main conclusions are as follows:In order to explore the influence of thinning on the spatial structure of artificial forest,stands with three different thinning intensities are taken as examples The study was carried out on a sample basis.The results showed that the trend of each thinning intensity was the same with the change of angular scale The Angle scale of thinning showed significant difference,the weak thinning showed random distribution on the whole,and the Severe thinning and moderate thinning showed aggregation distribution.As the mixing goes up High,the individual number of larix chinensis showed a significant decline trend,and the decline rate of individual number of intensive thinning was significantly higher than that of moderate thinning.Mixing of weak and strong thinning stands The mixing degree of weak thinning(Mi = 0.48)was close to that of moderate thinning,and the stand of strong thinning(Mi = 0.35)was mixed below that of weak thinning.Moderate thinning(Mi = 0.23)was mixed below moderate.The number of individuals of reference trees increased with the increase of the size ratio,and the other thinning intensities The stand had no significant change trend,the differentiation degree of thinning trees with weak degree was high,and the target reference tree was subject to competition pressure.A sample plot was established in the Larix principis-rupprechtii plantation operating area with three different thinning intensities.Hegyi simple competition index model was used to do quantitative expression and comparison on different tree species and core objective trees for competitive pressure.Also,changes of trees' competitive features caused by intermediate cutting and driving role were studied.The findings indicated that intermediate cutting could accelerate changes of trees' competitive features.In the sample plot with different thinning intensities,the competitive pressure pattern was present in the dissimilation with varying degrees.Diameter at breast height(DBH)and competitive pressure index of each thinning intensity could be greatly fitting by power function The degree ffitting was ranked as.:Moderate thinning(Lishangou)(R2=0.592)>Weak thinning(Dingyanggou)(R2=0.571)>Severe thinning(Wuyegou)(R2=0.500);With the increase of thinning intensities,object trees and target tees' competitive pressure was reduced;Intermediate cutting had the better role on relieving pressure for target trees with the larger competitive pressure.The competitive pressure difference suffered by target trees with different thinning intensities was extremely remarkable.The competitive pressure suffered by target trees with different thinning intensities was present in the declining trend with the increase of diameter class.The competitive pressure suffered by target trees with the small diameter class was larger than other diameter class.To explore the relationship between the inter-tree competition pressure and DBH growth of Larix principis-rupprechtii,the goal tree central round quadrat method was adopted to make investigations and researches on the thinning area of Larix principis-rupprechtii natural forest in Guandi mountain forest district.Theresults show that there was obvious difference in the increment of DBH of those goal trees given different competition pressures in 1998,and the value reduced as the competitive strength increased.The radial increment of Larix principis-rupprechtii shows a decreasing trend 10 years before the pressure was released,and it gradually turned to an increasing trend after the pressure was released,among which,the climbing speed of goal trees with weak competition of tending and thinning was higher than that of goal trees with moderate competitions,while the average DBH increment of goal trees of strength competitions had the slowest increase,and the trend was not obvious.The competition pressure index was of power function relationship with the DBH increment of15 years after cutting,the inflection point occurred where the competition pressure index was 1 and was tend to be flat after the value was over 2.The establishment of management system with target tree as the core can improve the growth model of forest under certain conditions by means of moderate interference and tending and thinning,so as to improve the forest quality accurately.