| China is a big country of the largest plantation,but the plantation multi-functional forest management encountered issues such as the structure of a single species,planting large concentration of biodiversity caused by degradation,soil degradation and others,it resulting in the traditional plantation forest is difficult to achieve the maximum value.As a valuable timber tree species,Phoebe is confronted with the problems of large scale destruction of natural forest,slow growth of plantation,unreasonable spatial structure of stand and so on.The structure determines the function,reasonable optimization of the stand structure will effectively improve the multi-function of the stand.Therefore,study on the structure and function of the plantation stand of Phoebe,explore the angle scale,the coupling relationship exists what and how to use the near natural management concept to improve Phoebe and other rare species of multifunctional benefits becomes an urgent problem between stand structure and stand mingling and size than the number represented by the function.This study takes the Phoebe bournei artificial forest as the research object in Jin-dong Forest Fann,using the forest management data of 4 year old pure forest,mixed forest and 14 years pure forest,mixed forest a total of 12 sample plots.Analysis on the characteristics of the structure of the plantation of Phoebe,establish 4 aspects of'productivity,carbon sequestration,conservation of soil,understory species diversity a total of 14 multi-functional evaluation index,comparative analysis the functions of pure and mixed forest,to carry out the correlation analysis of the spatial structure and the multifunctional factors of the forest.At last,the paper puts forward the multi-function optimization management measures of existing forest stands.The main contents and conclusions are as follows:(1)Analysis of the structural characteristics of the plantation of Phoebe.Analyzed the DBH and tree height by Weibull distribution.The results shows:In the aspect of diameter structure,the pure forest tended to large order,while the mixed forest was inclined to the trail order and more concentrated distribution.In the 4 year old mixed forest of 4-6 plots and 11,12 plots of the 14 year old mixed forest were all in accordance with the Weibull distribution curve,the diameter distribution of 4 year old Phoebe mixed forest showed the ideal stand diameter structure inverted "J" type.In the aspect of the tree height structure,it showed that the pure forest tended to trail order,and the mixed forest tended to be larger.In the diameter and tree height structure of mixed stand,the trend of forest differentiation appeared with the increase of age.From the spatial structure characteristics point of view,using the uniform angle,mingling degree and neighborhood comparison 3 of the uniform spatial structure analysis showed that the mixed forest has stronger competitive advantage than pure forest and the differentiation tendency appeared in mixed forest;The annual distribution of 4-year-old pure forest was evenly distributed,and the mixed forest of 4-year-old was randomly distributed,The 14-year-old plantation showed the spatial distribution pattern for the slug and dis-tribution of the species in the stand was consistent with that of the stand.the degree of isolation of mixed forest stand space generally high;In the comprehensive index re-flecting the degree of spatial structure,the mixed forest was the best.On the whole,the spatial structure of the mixed forest is very reasonable,which is the ideal stand structure model.(2)Analysis the multifunction of plantation of Phoebe.From soil conservation,species diversity,carbon sequestration and Productivity functions 4 multifunction indi-cators.The results shows:the productivity of the 4 year old and the mixed stand of the mixed forest of the 14 year old were 110.42m3/hm2,230.02 m3/hm2,respectively,which were higher than the pure forest at the same age and the volume of was 22.19 m3/hm2,192.64m3/hm2,there were significant differences among different forest types,which indicated that the mixed plantation was beneficial to increase the productivity of the forest.The carbon sequestration capacity of 12 plots was 1.0328?27.2475 t/hm2,showed the mixed planting had higher carbon sequestration ability than the pure forest,this is consistent with the trend of productivity function.From soil conservation,those results suggested that 14 years Phoebe mixed forest has better nutrient than pure forest,and 4 years Phoebe mixed forest undergrowth Chinese fir has more available elements than 4 years pure forest.The 4-year-old mixed afforestation of Cunninghamia lanceolata forest was higher than that of direct plantation.The number of herbaceous layer in pure forest increased with the increase of age,and the distribution was more uniform.On the whole,the mixed forest can play better multi-functions than the pure forest,and the mixed forest afforestation has the advantage in each function.(3)The relationship between spatial structure and multifunctional index of forest stand and model construction.There were some correlations between spatial structure factors and multifunctional indexes,the angle scale has a significant correlation with stand volume;neighborhood comparison and uniform angle have significant effects on stand carbon sequestration.The results showed that the relative distribution of forest trees could effectively improve the productivity and carbon sequestration in the young forest stage.The angle scale and the mixed degree have a significant effect on soil available N content,it showed that the higher the degree of mixed stand,the higher the medium speed nitrogen content;Shannon Werner index of shrub layer was significantly affected by the angle scale and the degree of mixing,while the herbaceous layer of Shannon Werner index was signilicantly influenced by the neighborhood comparison and the degree of mixing,which indicated that the spatial distribution of mixed affor-estation and forest could be related to the growth of tree shrubs.and the more compet-itive forest stand,the richer the diversity of herbaceous layer.(4)Multi-functional optimization management measures of existing forest stands in Jindong forest farm.In view of the large-scale Cunninghamia lanceolata plantation in Jindong Forest Farm,there are many problems caused by land load degradation,pest and disease damage,it is urgent to transform the cultivated coniferous to broad-leaved mixed forest with native tree species by using the near-natural and multi-functional concept,and put forward the multi-functional management mode of the Chinese fir—Phoebe bournei conifer forest and multi-functional management measures. |
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