Analysis Of Plant Community Structure And Spatial Pattern Of Deciduous Broad-leaved Forest In Baiyunshan Mountain

Based on the first survey data of 1 hm2 fixed monitoring plots of deciduous broad-leaved forest in the warm temperate zone and the northern subtropical transition zone,Baiyun Mountain,the canopy structure was investigated by hemispherical photography.Spatial variable analysis,point pattern analysis and principal component analysis were used to study the community structure and diversity maintenance mechanism of deciduous broad-leaved forest in Baiyun Mountain.The species composition and the structure of the deciduous broad-leaved forest in this area were analyzed in 5 aspects: the species composition,the structure of the diameter grade,the spatial distribution pattern,the interspecific and interspecific correlation,the negative density restriction effect and the canopy structure.The results are as follows:(1)there are 61 species of woody plants,belonging to 38 genera of 24 families and total 4301.Among them,Quercus Quercus,Huashan pine,forsythia and Pinus Pinus are dominant in the community.Rare species account for 12.28% of the total species and 47.37% of the total species.The maximum DBH of the plants in the sample is 40 cm,and the average DBH is 7.82 cm.The diameter structure of Quercus Quercus,Huashan pine,Pinus tabulaeformis,three dill and lacquer tree in the sample plots is partial normal distribution,and the structure distribution of Forsythia forsythia,short handle oak,Sorbus Sorbus and sandalwood has an inverted "J" type,and the DBH of most individuals is less than 5 cm.The number of individuals between DBH and 0~5 cm is 2174,accounting for 50.55% of the total plant number.The largest DBH in the plot is 40 cm,and the average DBH is 7.82 cm.(2)the population pattern analysis under the complete random zero model showed that the short handle oak,the three Yulu and the Sorbus Sorbus were aggregated on the whole research scale,while the other 6 species were mainly concentrated on the smaller scale.In general,the species was mainly concentrated in the sample plots,and the degree of species aggregation gradually weakened with the increase of the size of the sample.(3)in comparison with the spatial correlation of acute Quercus variabilis after the exclusion of habitat heterogeneity,it was found that,in general,the forsythia of DBH<10 cm and DBH<2 cm were protected by the same species of adult trees on the small scale,but were slightly repelled on the large scale,which was beneficial to the regeneration of the species.The adult tree of Quercus acute Quercus has no significant correlation to the young trees,but has a significant positive correlation to the small trees.The reasons may be influenced by many factors,such as environmental factors,the small year of seed and the restriction of diffusion.On the whole,the influence of other species on Quercus acute Quercus was not significant.The negative correlation was dominant in the Quercus variabilis and forsythia forsythia,but the 3 were negatively related to the other species,and the positive correlation in the small scale increased the survival rate of the small trees to some extent and alleviated the difficulty of renewal.(4)Quercus sharp and Quercus are affected by a certain degree of negative density restriction effect,and the short handle oak is negative density restriction effect on small scale,and the situation of sharp tooth Quercus is special.It shows negative density restriction effect on the scale of 6.5~12.5 m,and the main shrub species in the sample area does not show negative density restriction in the species,to a certain extent.It shows that its survival state is more susceptible to other species.(5)through the investigation and study of the 5 canopy light indexes,such as the average leaf dip angle,the transmittance ratio,the leaf area index,the scattering radiation under the canopy and the total direct radiation under the canopy,it was found that the canopy structure parameters Vis Sky,Dif Be and Dir Be three were positively correlated,LAI,MLA and GF were positively correlated,LAI was negatively correlated with Vis Sky,Dif Be and Dir Be,and cluster analysis was used.The method is divided into 4 types of illumination.Habitat 2,3 and 4 are distributed more closely in plots.