Study On Stand Structure And Undergrowth Vegetation Diversity Of Cunninghamia Lanceolata Ecological Public Welfare Forest

Biodiversity is one of the hot topics of forest ecology research.Studying the relation between stand structure and biodiversity helps to guide the operation and management of forest in a region.This paper takes the ecological public welfare forest of cunninghamia lanceolata as the study object, quantitatively analyzes the characteristics of forest stand structure factor and the undergrowth vegetation diversity, and it aims to study the relationship between forest stand structure and diversity of undergrowth vegetation. Finally,raised the structural adjustment measures which should be taked to increase the diversity of undergrowth vegetation. The main research contents and results are as follows:(l)The quantitative analysis of forest stand structure. The research contents include spatial structure and spatial structure, the study of non spatial structure include diameter structure and height structure, the study of spatial structure include forest layer index and open degree. The results of the study are as follows:The standard deviation of diameter structure increases in turn with the change of age group.young growth is partial to the smaller diameter class.its distribution is concentrated, the imitative effect of Weibull distributionand logarithmic normal distribution is good.half-mature forest and near-mature forest are partial to the middle and smaller diameter class.distribution is discrete, the imitative effect of Weibull distribution and normal distribution is better to. half-mature forest the imitative effect of three kinds of distribution function is not ideal to near-mature forest.The standard deviation of height structure increases in turn with the change of age group.young growth is partial to small tree and its distribution is concentrated,and the imitative effect of three kinds of distribution function is not ideal.half-mature forest and near-mature forest are partial to tall tree and their distribution is concentrated the imitative effect of normal distribution and Weibull distribution are better.The structure of forest layer index shows that the average of forest layer index to young growth half-mature forest and near-mature are0.14-0.340.22-0.460.17-0.34,forest layer index is little the trees are almost located in the middle and upper layer of forest,the understorey is rare,and the natural update of forest is insufficient.The structure of open degree shows that the average open degree of young growth is bigger, and it is between0.542-0.859, the growing space of trees are enough. The average open degree of half-mature forest and near-mature forest are lesser,0.294-0.395,and0.174-0.257,the growing space of trees are insufficient, which will influence the individual growth.(2)Diversity analysis of undergrowth shrub layer and herb layer. Research from the important value and diversity of species. The results showed that:In the matter of the important value of species, The important value of dominant species in the shrub layer and herb layer are generally lower, and the value in herb layer is slightly larger than it in shrub layer. Dominant species in shrub layer is mainly the Rhus chinensis.Patrinia scabiosifolia. Zanthoxylum simulans.and so on, dominant species in herb layer is mainlythe Oplismenus compositus.Polygala hongkongensis var. stenophylla. Indocalamus tessellatus and so on.Except a little sample plot, results show the characteristics that species diversity in shrub layer is greater than it in herb layer.At the same time species richness index,diversity index,evenness index first become large then small.(3)Study on the relationship between the stand structure and diversity of undergrowth. This paper study the relationship the stand structure and the species diversity index in shrub layer and herb layer by using the partial correlation analysis, The results showed that:The significant factors that affected the species diversity of shrub layer mainly had forest layer index and open degree. The correlation coefficient of forest layer index and species richness index S, forest layer index and diversity index D, H, forest layer index and the evenness index JD, JH were0.657,0.639,0.641,0.69,0.678respectively. The correlation coefficient of open degree and diversity index D, H, open degree and the evenness index JD, JH were0.651,0.665,0.707、0.723respectively.The impact factor is complex to herb layer,the significant impact factors are canopy density, mean height. The correlation coefficient of canopy density and species richness index S, canopy density and diversity index H were0.646,0.631 respectively. The correlation coefficient of mean height and the evenness index JD, JH respectively were-0.662,-0.708.(4)Raised measures of structure adjustment of stand.This study regard the significant structure factors that affecting species diversity as adjustment bases, To raise the cutting and replanting measures in sample of11, the results show that:after the adjustment,the stand has the transition to "stratified-different ages-mixed" state.