Plant Biodiversity And Its Spatial Pattern In Dabanying Nature Reserve,Chongqing,China

In order to gain a better understanding of the plant diversity in Dabanying Nature Reserve,Chongqing,China,the author analyzes the species diversity,ecosystem diversity and landscape diversity of plant by using the method of landscape pattern index,species diversity index and Arcgis spatial statistical analysis.Besides,the spatial relationship between ecosystem diversity and landscape diversity are analyzed by using sample space sampling and transfer matrix,so as to understand the spatial diversity pattern.The central conclusions are:(1)The species diversity of vascular plants in study areas is abundant,with a total of 197 families,867 genera and 2121 species.The vascular plants of study area has the advatange of family and genera,especially the gymnosperms,they all have percenta ge more than 75% comparing with the vascular plants of Chongqing.Besides,there are 29 species of rare and endangered plants in the study area.Among them,there are about 20 species of rare or endangered plants in the reserve.And there are 9 species plants of vulnerable species.The floristic characteristics of plant are that the family dominant of tropical nature while the genera dominant of temperate nature.And the proportion of temperate nature is significantly higher than that tropical nature,this show that the floristic have obvious transitional nature.(2)The ecosystem of the plant are divided into fore first-class ecosystems(broad-leaved forest,coniferous forest,shrub / shrub-grass and other ecosystem)and 10 secondary-class ecosystems(evergreen broad-leaved forest,evergreen and deciduous broad-leaved forest,broad-leaved broad-leaved forest,coniferous and broad-leaved mixed forest,warm coniferous forest,shrub and shrub – grass,farmland,settlements and roads ecosystem).The natural degree of ecosystem decreased with the decrease of altitude,the decrease of slope and the increase of soil ptye.The three-dimensional diversity features of typical ecosystems are different.The evergreen broad-leaved forest diversity is: shrub layer> arbor layer> herbaceous layer;warm coniferous forest diversity is: shrub layer> herbaceous layer> arbor layer.evergreen and deciduous broad-leaved mixed forest diversity is: tree layer> shrub layer> herb layer.The coniferous and broad-leaved mixed forest and deciduous broad-leaved forest diversity are: herb layer> shrub layer> tree layer.The order of diversity among the typical ecosystems is: evergreen broad-leaved forest>evergreen and deciduous broad-leaved mixed forest> broad-leaved broad-leaved forest> coniferous and broad-leaved mixed forest> warm coniferous forest> shrub> shrub.(3)The landscape are divided into six types categories of first-class landscape and ten categories of secondary landscape.The diversity of landscape types shows that the landscape type of the study area is more,but the proportion of each landscape type is not uniform.The whole landscape is dominated by warm coniferous forest,shrub landscapes and cultivated landscapes;Patches diversity analysis shows that the number of forest landscape patches is small,but the patch area was large,and the patch shape was complicated,its heterogeneity was low.The indices of shrubs and shrub-grass indicate that the patch density is high and the mean patch size is smaller than the forest landscape and the patch shape is also simpler.While the settlement landscape and road landscape have the smallest mean patch size and simplest shape as well as highest heterogeneity;Landscape diversity analysis shows that the order of fragmentation is forest landscape> shrubs and shrub-grass landscape> cultivated land,settlement and road landscape.These indicate that the greater impactions of man-made,the higher fragmentation are.The separation degree index show that the forest landscape is relatively small as a whole.(4)The high diversity ecosystems area mainly bulk-shaped distribute in the study area,and mostly concentrated in the western part of the whole study area.The high diversity ecosystem area are featured with high altitude,steep slope,low achievable and less human disturbance.Landscape diversity area distribute unevenly in study area.The "low-value diversity zone" is mainly distributed in the west of the core area B and the north of the buffer zone A.The landscape distribution of low-value diversity zone are Similar to the high-value zone of the ecosystem diversity.The area of two levels’ diversity is featured two side low,middle high,shaped inverted "U".and the two level are negatively correlated in the space pattern.Ecosystem level diversity High and low values often correspond to low-value and high-value areas of landscape diversity respectly.Two-level landscape and ecosystem diversity "conversion" situation is complex,the area "conversion" roughly along the median area of rotation symmetry.In terms of the distribution law of the conversion types,the "transformation" relationship between the very low-value area of the ecosystem and the diversity of the landscape is fragmented,and the distribution of the diversity of the other ecosystems is revealed Structure distribution,corresponding to the larger the patch area of the ecosystem,the more obvious the structure of the circle.