| Forest has complex structure and function.To a great extent,the function of forest depends on whether the structure is reasonable or not.Stand structure affects individual growth space.Optimizing the stand structure is an important way to cultivate multi-functional forest.A large number of scientific research shows that the multi-function of the stand is closely related to the stand structure and the site conditions,and there is a complex relationship between them.It is very important to study the coupling relationship between forest structure and multi-functionThe mixed forest of Chinese fir-Phoebe bournei in Jindong forest farm,Yongzhou City,Hunan Province was studied as the research object in this paper.Based on the binary distribution analysis of stand spatial structure and the analysis of stand multi-functional dynamic changes.The coupling relationship among the structure,site conditions and multi-function of the stand was studied by using the structural equation model(SEM),so as to analyze the main structural factors affecting the multi-function of the stand.And guide the design of the multi-function management scheme of the mixed forest of Chinese fir-Phoebe bournei.The main research contents and conclusions are as follows:(1)Dynamic analysis of the stand structure characteristics of Chinese fir-Phoebe bournei mixed forest.Through the analysis of the estimated values of the fitting parameters of the stand diameter,tree height and Weibull distribution,it can be seen from the diameter structure that the diameter distribution tends to the minor diameter order,but the deviation degree is small.The estimated values of the shape parameter C of the diameter Weibull distribution function are all between 1-4.5,and the diameter distribution of the stand presents the inverted"J" type.From the aspect of tree height structure,the tree height is mainly concentrated in the 4-10 high order,and the distribution curve of tree height is in the shape of single peak mountain.In the dynamic changes of diameter and tree height structure,the trend of tree differentiation appears with the growth of age.It can be seen from the binary distribution of the spatial structure of the mixed stand of Chinese fir-Phoebe bournei that the binary distribution laws of the mixed degree and the angular scale size ratio of the eight sample plots are basically similar,and the angular scale 0.5 as the dividing line shows a significant normal distribution,indicating that the angular scale is closely related to the mixed degree and the size ratio,and the too large or too small angular scale is not conducive to the mixed forest,The binary distribution of the mixed degree and the size ratio shows an increasing trend with the increase of the mixed degree,but the close degree between them is not very high.The mixed forest of Chinese fir-Phoebe bournei are mostly in random distribution,the mixed degree of stands is not very high,and the binary distribution characteristics of stand spatial structure well reflect the growth characteristics of stands.(2)Dynamic analysis of multi-functional characteristics of mixed forest of Chinese fir-Phoebe bournei.Based on the three main functions of productivity function,carbon sequestration function and species diversity function,this paper makes a dynamic analysis on the multi-function of mixed forest of Chinese fir-Phoebe bournei.The results showed that the multi-function of the stand improved significantly with the extension of management time.From the perspective of stand productivity function,the average stand volume of the mixed plot of Chinese fir-Phoebe bournei was 95.64 m3/hm2,which was in the middle level.Among them,the productivity of sample plot 5,6 and 8 is low,and the average stand volume was 55.78 m3/hm2,28.46 m3/hm2 and 69.51 m3/hm2.In plots 1 to 4 and plot 7 because of the replanting of young Phoebe bournei and Taxus chinensis under their forests,their forest productivity is relatively high.The average stand volume is 146.43 m3/hm2,121.22 m3/hm2,104.52 m3/hm2,136.36 m3/hm2 and 102.86 m3/hm2;from the perspective of carbon fixation function,the total carbon storage of the mixed forest of Chinese fir-Phoebe bournei is between 107.74?129.47 t/hm2,among which the carbon storage of tree layer of sample plot 1 to 4 is higher than that in the plots of 5 to 8.The carbon storage of the arbor layer in plot 6 is the lowest,which is consistent with the law of the productivity function of the stand.In terms of the function of species diversity,the SDCI of the mixed forest is 0.5771,which is in the middle level.Among them,plot 3,5,6 and plot 8 have a higher level of species diversity,while the other four sample plots have a lower level of species diversity,among which sample plot 4 has the lowest level of species diversity,and sample plot 8 has the highest level of species diversity.(3)Structural equation model of stand structure,site condition and stand function.The most important factor affecting the multi-function of the stand is the site condition.The total influence coefficient of the site condition on the multi-function of the stand is 2.484,and the direct influence coefficient is 1.571.The total influence coefficient of the site condition on the productivity function is 1.221,the total influence coefficient of the carbon fixation function is 0.850,and the total influence coefficient of the species diversity function is 0.413.The total influence coefficient of stand structure on stand function is 1.882,the direct influence coefficient is 1.603,among which the total influence coefficient of non spatial structure on stand multi-function is 1.615,and the total influence coefficient of spatial structure on stand multi-function is 0.267,among which the spatial structure of stand has a negative influence on species diversity,the direct influence coefficient is-0.249,no indirect influence.According to the path coefficient calculated by the structural equation model,in the process of forest management,timely pruning and thinning,reasonable tending and improving the forest structure,increasing the light transmittance of the forest,improving the water and fertilizer management of the forest land,promoting the regeneration of undergrowth plants and the improvement of species diversity,maintaining the stability of the forest community,and making the forest develop in a more optimized direction.(4)The multi-functional management technology of mixed forest of Chinese fir-Phoebe bournei.Based on the dynamic analysis of stand structure and multi-function,as well as the research results of non spatial structure,spatial structure,site condition and multi-function structural equation model of stand.This paper analyzes the current situation and target forest facies of mixed forest of Chinese fir-Phoebe bournei in the forest farm,and then divides different construction areas.From the perspective of near natural forest management,the full cycle management plan is designed,and the multi-functional management measures are designed for the mixed forest of Chinese fir-Phoebe bournei in Jindong forest farm. |
PDF Full Text Request