Effect Of Thinning On The Growth Of Chinese Fir

Forest tending is an essential measure to promote the growth of forest trees,to improve the quality of forest trees and to maximize the benefits of forests.Chinese fir in Hunan artificial timber has a significant impact,is the focus of forest tending tree species.This research is based on the central finance forest tending subsidy pilot project,with the tending sample and the same as a group,set up 8 groups of samples in the range of Hunan Province,Including middle age and near mature forest of Chinese fir,observing the effect of tending on the growth of trees for 4 years,The effects of tending on DBH,height,individual volume and biomass per year were analyzed,To evaluate the effect of tending,so as to provide scientific basis for the further development of forest tending.The main results are as follows:1)The average DBH growth rate of tending samples was significantly higher than that of control samples.The average annual growth rate of the average DBH of tending samples was B1(Suxian area),which was as high as 1.7 cm ·a-1,The average annual growth rate of stand diameter was B1(Suxian area)>A1(Youxian)>D1(Jin Dong area)/HI(Yueyang)>C1(Suxian District)>G1(Yueyang)>E1(Jin Dong area)>F1(Luxi);The difference between the average annual growth rate and the difference between the control and D was 0.45 cm·a-1,and the lowest in F(Luxi)was 0.07 cm·a-1.Tending has a significant effect on the DBH growth of Chinese fir,and the average tending benefit is 47.7%.Tending the benefits of the highest Jin Dong area tending benefits greater than 70.0%,the lowest tending benefits for Youxian,tending benefits less than 10.0%.The effect of middle aged forest was better than that of near mature forest.2)There was no significant difference in the average tree height of the cultivated sample and the control sample,The maximum annual growth of the forest was the same as that of the control.The maximum B in the Suxian area was 0.12 m·a-1,and the Jin Dong area D was 0.03 negative.In general,tending thinning had little effect on the growth of Chinese fir trees,and the average tending benefit was only 14.5%.3)The growth rate of individual tree volume was significantly higher than that of the control sample.The average annual growth of single plant volume A1(Youxian)is 0.0273 in3·a-1,Sort for A1(Youxian)>D1(Jin Dong area)>H1(Yueyang)>B1(Suxian District)>G1(Yueyang)>E1(Jin Dong area)>C1(Suxian District)>F1(Luxi);The average annual growth of individual plant volume is the difference between tending and control D(Jin Dong area)up to 0.0088 m3·a-,F(Luxi)minimum 0.0015 m3·a-1.Tending has a significant effect on the growth of Chinese fir,and the average tending benefit is 37.5%.The group with the highest benefit was found in the E formation of the Jin Dong area,tending to be more than 60%,and the tending benefit was the lowest in Youxian.4)The growth rate of biomass per plant was significantly higher than that in control plots.The average annual growth of biomass per plant A1(Youxian)was 15.14kg·a-1,Sort for A1(Youxian)>D1(Jin Dong area)>H1(Yueyang)>G1(Yueyang)>B1(Suxian District)>E1(Jin Dong area)>C1(Suxian District)>F1(Luxi);The difference between the average annual growth increment and the control of individual biomass H(Yueyang county)was 4.8 kg·a-1,F(Luxi county)was the lowest of 0.78 kg· a-1.Tending had a significant effect on the biomass growth of Chinese fir,and the average yield was 36%.The group with the highest benefit was found in the E formation of the Jin Dong area,tending to be more than 60%,and the tending benefit was the lowest in Youxian.