| Pinus massoniana is an important species of timber forest in southern my country.Evaluating the rationality of its stand structure,exploring its growth pattern and obtaining the multifunctional benefits of the forest is an important part of the sustainable management of Pinus massoniana plantation.This paper takes Pinus massoniana plantation in Wudang District of Guiyang City as the research object.The thinning,growth felling implemented for 18 years of trees and the cutting and weeding implemented for 9 years of trees are used to establish a control sample of 20m×30m after 6 years.3 sets of repetitions,a total of 18 survey plots,were used to investigate the changes in spatial structure indicators such as tree height,diameter at breast height,stand density,size ratio,forest layer differentiation,etc.;and then 6 functions such as Weibull Fitting the distribution characteristics of diameter at breast height and tree height,using index mean value evaluation method(IAVE)and index goodness evaluation method(IPVE)two evaluation models to evaluate its spatial heterogeneity;then using growth cone method according to dominant wood,average wood,A total of 72 standing trees were selected for the inferior trees to study the growth process of the trees,and the results of tending after 6 years of tending were comprehensively evaluated to provide theoretical support for the sustainable management of Pinus massoniana.The results show:(1)The quality of the target tree was improved after tending,and the ideal average value of single tree quality was higher than that of the control stand.The highest was 0.914 for the growth,cutting and tending stand,and the lowest was 0.413 for the control stand for cutting and weeding and tending;The results of advanced distribution function fitting show that the proportion of large-diameter trees in the three tending stands is higher than that of the control stands,and generally obeys the Weibull distribution.However,the optimal distribution function is that the difference between the growth felling stand and the control stand is the largest.Cutting and tending has the most significant effect on realizing the optimization and adjustment of diameter at breast height and tree height structure of this Pinus massoniana forest.(2)The spatial structure of the forest stand was optimized after tending,and the growth and felling stands were the best;the spatial heterogeneity of the stand in the 18 sample plots was at an average[0.4,0.6)state,and the spatial structure of the existing stands had the potential for transformation It is still large;the index mean value evaluation result,the spatial structure heterogeneity index range is 0.4051-0.4897,the index goodness evaluation result,the spatial structure heterogeneity index range is 0.4196-0.5266,which can be obtained from the evaluation of the spatial index goodness level The spatial heterogeneity of the forest stands is higher than that of the control,and the optimal regulation effect of the forest stand spatial structure is the best after the implementation of growth cutting and tending.(3)The growth of forest trees after tending is promoted,and the growth and cutting effect is the most prominent;the difference in average annual volume growth between thinning and tending and control stands reaches a significant level;compared with the average growth of debarked trees,the thinning forest has increased by 1.70 cm compared with the control,the growth of the harvested forest increased by 2.50 cm compared with the control,and the shrub and weeded forest increased by 0.62 cm compared with the control;the maximum annual growth at DBH of the three tending forests all appeared in the 10th year,and the fast-growing period was 0 During-10 years,the growth pattern of Pinus massoniana was in line with the peak growth of tending stands higher than the control stand;the growth of Pinus massoniana trees of different dominance grades after tending was promoted;the 5 growth mathematical models were reasonable in terms of the growth results Richards has the highest curve fitting accuracy,with correlation coefficients above 0.9,which provides a model reference for the Pinus massoniana growth prediction.(4)The implementation of tending plays a key role in the increase of Pinus massoniana biomass and forest land productivity.After tending,the tree layer biomass is increased,and the tree layer biomass of the thinned forest is increased by 7.85t/hm~2 compared with the control.The control increased by 5.42t/hm~2,and the brush-cutting and weeding forest increased by11.87t/hm~2 compared with the control;the three tending measures had significant effects on the individual tree biomass of Pinus massoniana.Thinning,tending and brush cutting,weeding and tending mainly affected the forest.The biomass of common trees within the forest has a significant impact,while the growth and tending has a significant impact on the biomass of each dominant grade of the forest.(5)In the process of tending implementation,the spatial structure optimization of Pinus massoniana forest under different tending measures can be achieved by adjusting specific spatial indicators;research shows that the highest correlation with thinning and tending stands is the forest layer differentiation and density indicators,The spatial index of the thinning and tending forest stands significantly different from the control is the size ratio and the ideal state of single tree quality;the angle scale index is the most relevant to the growth cutting and tending,and the growth cutting and tending forest stands have a significant difference compared with the control.The indicators are the angular scale,the ideal state of single tree quality and the ideal state of succession;the density index has the highest correlation with brush cutting,weeding and tending;Stratum differentiation,density and succession ideals. |
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