The Characteristics Of Survival Community And The Environmental Factors Affecting The Growth Of Calanthe Sieboldii Decne

Calanthe sieboldii belonging to Orchidaceae Juss.,Calanthe R.Br.,is one of the extremely small population species that need to be rescued urgently in the Wild Plant Protection Project Planning for Extremely Small Population species.In order to study the habitat characteristics and the relationship between Calanthe sieboldii growth and its environmental factors,we carried out a typical sample survey for Calanthe sieboldii survival community from March to May in 2017 in Jingxian County of Anhui Province.Based on the data of 18 sample plots and 22 quadrats,we analyzed the species diversity,the interspecific association of herb layer in Calanthe sieboldii survival community by using variance ratio(VR),Fisher exact test,Pearson's correlation coefficient,Spearman's rank correlation coefficient,the niche characteristicswith Levins index and Hurlbert index,,and the relationship between Calanthe sieboldii growth and environmental factors by using RDA analysis,Regression analysis,and Maxent model.The conclusions are as follows:(1)those biodiversity indices can reflect diversity level of herb layer in community well,and the species diversity of herb layer was low.Population density was closely related to species diversity.The overall associations between 11 main species of herb layer in community were extremely significantly positively correlated,suggesting a relatively stable succession status in herb layer of community.The results of Fisher exact test,Pearson's correlation coefficient and Spearman's rank correlation coefficient were consistent.Negative connection was in a dominant position between species,reflecting that it tended to distribute independently.The structure of herb layer in community is still in the development stage.(2)It had an obvious advantage in the herb layer in the community of Calanthe sieboldii.Niche overlaps existed among the main species in the herb layer,but the degree of overlap was low,interspecific competition was not intense,and environmental resources could be sufficiently shared by different species.The herb layer in the community was in a relatively stable condition.(3)canopy density,elevation,aspect are very important environmental factors that influence Calanthe sieboldii growth,and higher canopy density,higher elevation and schattenseite are suiteble environmental factors for Calanthe sieboldii growth.Partial correlation analysis showed:Slope position is the key environmental factor that affect plant height growth.Canopy density,rapid available phosphorus and total phosphorus in soil are the most important factors impacting the leaf length growth.The most important environmental factors of leaf width growth are slope position,canopy density and alkali hydrolysable nitrogen.There is no no significant correlation between the amount of flowers and environmental factors,but it is greatly influenced by the height of Calanthe sieboldii.(4)The result of the potential distribution showed the area of the most suitable region in China is 234291km2 of Calanthe sieboldii.The potential suitable distribution area of Amur corktree in China is mainly concentrated in Zhejiang,most areas of Hunan,southern Anhui,Southwestern Hubei,and northeastern Taiwan.The daily mean temperature difference between day and night(49.4%),Variation coefficient of precipitation(29.2%),slope(7.6%)and Isothermal property(7.2%)are the 4 main environmental factors influencing the distribution of the Calanthe sieboldii,and the total rate of contribution are93.3%.