Research On Population Characteristics Of Rare And Endangered Plant Styrax Zhejiangensis

Distributed in Taohuawu of Longjiang Forest district,Jiandailin,Zhejiang province.Styrax zhejiangensis is a unique wild plant with an extremely small population in Zhejiang province,and plays a vital role in its protection and research on biodiversity maintenance and plant conservation.Through carrying out the field research on community of Styrax zhejiangensis,this study analyzes its composition of the community species,vertical structure of the community,niche characteristics,interspecific association,population diameter age structure,static life table and survival curve of population to evaluate community and population characteristics of Styrax zhejiangensis and discusses the reason of its endangered status by combining with the observation results of morphological characteristics.The main research results are as follows:(1)Styrax zhejiangensis is distributed in the shrub layer of secondary evergreen broad-leaved forest 150-260m above sea level in Zhejiang province and forest canopy density is mainly between 0.85-0.95.Currently,the number of investigated trees in the sample plot is 114(66 clusters).The growth environment is mainly the north slope or northwest slope of the stream side,which is relatively damp,and the strongly acidic soil with an average pH value of 4.48±0.25.There are about 91 species of plants in community of Styrax zhejiangensis.About 65 species of trees and shrubs belong to 49 genera and 33 families.They include Styracaceae,Aquifoliaceae,Fagaceae,Theaceae,Lauraceae,Ulmaceae,Ericaceae,etc.(2)Styrax zhejiangensis and Eurya japonica has the highest niche overlap with similar living environment;interspecific association results show that it competes for resources with Indocalamus tessellatus,Eurya japonica,Ilex chinensis etc.(3)The survival curve of Styrax zhejiangensis tends to be the type Deevey-? and species shows a trend of decline.Among which,?-? age class is quite few,accounting for only 14.91%of the total number,and individual number of ?-? age class is quite much,accounting for 64.04%of the total number.The lack of seedlings under the forest has a certain effect on the population structure.In addition,external interference factors will lead to the gradual degradation of the population.And it tends to age when the population is predicted,gradually declining.(4)Having solitary unisex flower,Styrax zhejiangensis has about 25-day flowering period,and its fruit ripening needs up to 4 months;The average Pola axis length of pollen grains IS54.16±0.585 microns,and the average equatorial length is 27.32±0.505 microns.(5)The fruit of Styrax zhejiangensis is capsule,containing 1-2 seeds and the seeds are similar to oval shape,with dark brown colour;Hard and dense into being lignificated,seed coat's surface is smooth with poor water permeability and seed kernel rich in oil,resulting in poor water absorption performance of the seed.In addition,the setting rate of Styrax zhejiangensis is between around 25.9%to 32.7%,which is at a low level.Continuous rainfall will aggravate the phenomenon of falling flowers and fruit and shorten the flowering time.