Community Characteristics And Ecological Functions Of The Limestone Mountains In Shanxi

The limestone mountains are extremely sensitive and fragile areas of ecological environment and the key areas for vegetation ecological restoration and reconstruction.It is of great significance for rational vegetation development and utilization,the selection and optimization of ecological restoration and reconstruction mode,and regional ecosystem management to clarify the characteristics and ecosystem functions of plant communities in the limestone mountains of Shanxi from a regional scale.In this study,based on the environmental factors and the community data by the systematic field investigation of representative scrub-grassland communities of the limestone mountains in Shanxi Province,we researched the floristic composition and geographical characteristics,and analyzed the main shrub-grass community types and the dominant environmental factors influencing the community distribution in limestone mountains by quantitative ecological approaches,then evaluated the comprehensive ecological function of typical communities.The results as follows:The species richness of seed plants in the limestone mountains of Shanxi was relatively low,which were dominated by angiosperms;The vegetation types were mainly shrub-grass communities consisting of dwarf shrubs and herbs,and herbaceous plants were more abundant;Among the three vegetation belts,the richness of families,genera and species was lowest in the Southern temperate steppe zone;The composition of the flora was complex.The oligospecies families and monotypic genera belonged to the main body of the family and the genus,and the distribution of species in the families and genera were unbalanced,which were concentrated in large and medium families and monotypic genera;Analysis based on genera showed that the floristic elements in the region were diversity,and the temperate floristic elements made significant dominant in genera.The results also showed that the flora was different among the three vegetation belts,and the proportion of temperate components in the southern temperate steppe zone was more than the others,while the proportion of tropical components was relatively lower;The dominant species of limestone mountainous areas in different vegetation zones had visible differences,showing the adaptability to habitat conditions and characterized by drought and barren resistance,developed roots,etc.The TWINSPAN quantitative classification divided the communities surveyed into ten formations,the typical formation types were Form.Vitex negundo var.heterophylla,Form.Rhamnus parvifolia,Form.Rhamnus bungeana,Form.Bothriochloa ischaemum,Form.Gleditsia microphylla.The CCA analysis reflected the distribution range of ten formations and the relationships between formation types and the environmental factors.The CCA ranking indicated the community distribution pattern was affected by the comprehensive effects of mean annual temperature,mean annual precipitation and elevation revealing that the shared effects of energy and moisture were the most crucial factors impacting the community distribution.There were abvious trends in latitude for vegetation and mean annual temperature.This paper applied for the principal components analysis and established comprehensive evaluation model to evaluate the ecological function of communities,and we found that the contribution of species diversity to the community ecological function was greater than that of soil nutrient circulation and conservation.The higher species diversity,the higher comprehensive evaluation values.The variation partitioning analysis demonstrated that the effect of environmental factors had much higher explanation rate than the effect of biotic factor on the ecological function of communities and hydrothermal conditions were main reason of ecological function heterogeneity.Environmental factors played a major role in species diversity.