Phytocoenological Features And Spatial Genetic Structure Of Endangered Species Sinocalycanthus Chinensis

Sinocalycanthus chinensis Cheng et S.Y.Chang,the only representative in the genus Sinocalycanthus in the family Calycanthaceae,is an endangered deciduous shrubs and mainly distributed in Linan City and Tiantai County in Zhejiang Province and Jixi County in Anhui Province.S. chinensis is recorded as the national second class protection plants in China with limited wild resources and a relic species from the tertiary.Based on the detailed plot investigation of S.chinensis community, the phytocoenological features and population structure in Dalei Mountain,and spatial spatial genetic structure pattern in Dalei Mountain and Darning Mountain were studied systematically,which could understand the status and distribution of S.chinensis and provid the theoretical basis for establishing reasonable conservation strategies.The main conclusions were as follows:1,They belong to 8 Main Types of Communities.There were 184 species of seed plants in S. chinensis community,belonging to 156 genera,67 families.The florae of seed plants presented a diversified and complicated composition,including 12 types,among which the east Asia distribution compositions made significant dominant and the the north temperate elements took some percentage. Based on the species important value,the S.chinensis community in Dalei Mountain could be divided into 8 community types:P.heterocycla forest,C.fortunei+C.lanceolata forest,C.fortunei forest,C. fortunei+P.massoniana forest,C.fortunei+L.glauca forest,C.fortunei+S.superba forest,L. glauca+C.fortunei forest and Q.serrata var.brevipetiolata+E.muricata forest.Based on Raunkiaer's life-form statistics,the life-form phaenerophyte class of the community ranks the first in number.The leaves of the community are mainly mesophyll,simple,herbaceous and unentire.The community's vertical structures can be divided into tree layer,shrub layer,herb layer and some interlayer plants. 2,In different communities,the species richness and species diversity index of the woody plants is highest in Cunninghamia lanceolata+Schima superba forest,the community evenness is highest in C. lanceolata forest,and these index is lowest in bamboo grove.The species richness of the herb plants is highest in C lanceolata+Pinus massoniana forest and lowest in C.lanceolata forest.The species diversity index and community evenness of the herb plants is highest in bamboo grove and lowest in Quercus serrata var.brevipetiolata+Eurya muricata forest.In the vertical structure of these different communities,the species richness and species diversity index of tree layer are lower than those of shrub layer,the species diversity of herb layer is great varied in different communities.The correlation analysis showed that there is great correlation existed between the species diversity of S.chinensis community and soil organic matter content in which organic matter content is positively related to species diversity of the woody plants but negative to the herb plants significantly,respectively.3,The age structure for S.chinensis population of P.heterocycla forest(S1),C.fortunei+P. massoniana forest(S5) and C.fortunei+L.glauca forest(S6,S7) are developing;and P.heterocycla forest(S2),C.fortunei+C.lanceolata forest(S3),C.fortunei forest(S4),L.glauca+C. fortunei forest(S9) is stable,but C.fortunei+S.superba forest(S8) and Q.serrata var.brevipetiolata+ E.muricata forest(S10) are decling.Except population C.fortunei forest and L.glauca+C.fortunei forest,the spatial distributive pattern of other populations belonged to progressive type.4,The spatial genetic structure of S.chinensis in Dalei Mountain and Daming Mountain were measured with spatial autocorrelation analysis.The results showed as follows:there was significant spatial genetic structure at Daming Mountain,and the modle of spatial distribution was aggregated-random-uniform.Individuals at ageâ… and ageâ…¢didn't show significant aggregated distribution,and the modle of spatial distribution were random.There was significant spatial genetic at 0-4.95m distance class of individuals at ageâ…¡showing aggregation distribution pattern.All individuals and different age individuals in populations of Dalei Mountain were distributed randomly.Spatial genetic structure was mainly affected by limited dispersal of pollens and seeds,heterogeneity of microenvironment and density of population.The different spatial distribution patterns may be attributed to the different heterogeneity of microenvironment and human disturbance.