Research On The Interactive Relationship Between Spatial Heterogeneity And Species Diversity Of Meandering River

Following the holistic conceptual model for the structure and function of river ecosystems(HCM),considering the technical requirements of river restoration,this dissertation takes the spatial heterogeneity characteristics of meandering river as a starting point and chooses the natural Chishui River as a study case.Data obtaining from field investigation and document were analyzed using multivariate statistical analysis methods such as redundancy analysis(RDA),canonical correlation analysis(CCorA),cluster analysis(CA)and regression analysis(RA),as well as River2D eco-hydraulics model.The quantitative relationships between spatial heterogeneity of meandering river and biodiversity at the meso-scale of reach and micro-scale of habitat were examined.To sum up,the main contents and results of the research are as follows:(1)The quantitative relationships between spatial heterogeneity of meandering river and biodiversity were studied through field investigation,ecological hydraulics simulation and statistical analysis.Achievements of the research enrich the holistic conceptual model for the structure and function of river ecosystems(HCM)and have some scientific values on revealing the rule of river ecosystem structure and function.(2)River spatial heterogeneity is defined as the spatial irregularity and complexity of hydro-geomorphology.It contains the spatial heterogeneity of geomorphology and diversity of hydraulic conditions.Formation mechanism,influencing factors,the structure of spatial heterogeneity and ecological function of meandering river were discussed.Quantitative indexes to evaluate river spatial heterogeneity were put forward at multi-scales.(3)Combined with the results of substrate screening test,non-uniform coefficient and curvature coefficient of substrate were chosen to quantify spatial heterogeneity of geomorphology at micro-habitat scale.By conducting cluster analysis to the water quality,phytoplankton and periphyton,the mainstream of the Chishui River was divided into three types:slightly disturbed reach,moderately disturbed reach and severely disturbed reach.Regression analysis was carried out in studying the correlation between non-uniformity coefficient and curvature coefficient of substrate,and species diversity of river macro-invertebrates.The results show that there were significant positive correlations between species diversity of macro-invertebrates and substrate non-uniformity coefficient,thus a regression equation was established.(4)Based on the positive correlation between species diversity of macro-invertebrates and non-uniformity coefficient of substrate,a general control criteria for non-uniform coefficient and curvature coefficient of substrate was put forward,which can be used as a reference for the substrate restoration in the tributaries of the upper Yangtze River.(5)Regarding the meandering degree as river spatial heterogeneity evaluation index in reach scale,the study selected the Yangtze River basin endemic fish Procypris rabaudi as an indicator species,constructed the habitat suitability curve of substrate,velocity and water depth,and analyzed the weighted Usable Area(WUA)for Procypris rabaudi under different flow conditions in meandering reach and straight low sinuosity reach.The results indicate that the meandering reach has a higher habitat WUA because of the more various hydraulic conditions,which can also provide shelter for fishes in the flood season.(6)According to the research results of this dissertation,the key river restoration technology and suggestions for the Chishui River protection and restoration were proposed.