Effect Of Thinning On Growth,structure And Regeneration Of Main Plantations In Linkou Forestry Bureau

This article is based on the plots of different age groups and different tending intensities of Pinus koraiensis,Larix gmelini and Picea asperata plantations of Linkou forestry bureau in Mudanjiang city,Heilongjiang province.There were 27 experimental plots were set up in 2016.Thinning experiments were carried out with three different intensities:low(10%-20%),medium(20-40%)and high(more than 40%).Survey of sapling regeneration and shrub-herb biodiversity data of the sample plots and basic factors of single tree were measured before and after the thinning.First,the influence of thinning intensity on growth of different stand types and different age groups was analyzed by Anova and multiple comparisons,and the optimal thinning intensity grade of different stand types and different age groups was determined.The effect of different thinning intensities on the projected area of single canopy was used to determine the effective living space of single tree.The Weibull distribution function was used to fit the functional distribution of the diameter structure of different stand types,and the dynamic variation diagram of the diameter structure was drawn.Based on the traditional diameter-height model in forestry,the optimal height curve model of different tree species including thinning effect with the method of parameterized was established.This paper analyzed the whole sapling regeneration rule,compared the sapling regeneration difference under different stand types,and established the seedling regeneration distribution model of main sapling in different stand types.Finally,through the investigation data of shrub-herbage,the basic characteristics of the whole shrub-herbage were analyzed,the community diversity index was calculated,and the overall rules of shrub and herbage biodiversity under different stand types and different thinning intensities were analyzed.The real aim is to systematically evaluate and analyze the stand growth,stand structure and biodiversity of main conifer species thinning in Linkou forestry bureau.The results showed that1)High intensity thinning is more suitable for young Korean pine forest,larch young forest and larch middle age forest.Medium intensity thinning is more suitable for immature Korean pine forest and young spruce forest.The species with the largest growth increase after thinning sorted by larch,spruce and Korean pine.2)The effective living space area of young Korean pine forest is 10-25 square meters;The 10-30 square meters is best for the middle age forest of Korean pine;The effective living space area of young larch forest is 5-12 square meters;The effective living space area of mid-age larch forest is 10-20 square meters;The effective canopy projection area of young spruce forest is 5-10 square meters.3)After thinning,the three-parameter Weibull of the three conifer species changed to a certain extent compared with the control plot,and the position parameters,scale parameters and shape parameters all increased to varying degrees.After thinning,the diameter structure developed towards a more stable state.4)Logistic model is more suitable for the construction of tree height curve of tree species studied in this paper.By introducing thinning effect factor and re-parameterization method,the goodness of fit and prediction accuracy of the model can be effectively improved.5)The number of seedlings in the stand obeys a certain distribution rule,Acer ginnala obeys normal distribution,Quercus mongolica obeys Neiman type A distribution,Fraxinus mandschurica obeys negative binomial distribution,and Pinus koraiensis obeys poisson distribution.6)The calculation of biodiversity index set indicates that larch plantation has the highest biodiversity index set,followed by Korean pine plantation and spruce plantation.Thinning can effectively improve the biodiversity of shrubs and herbaceous plants.