Study On The Functional Assessment Of Water Sensitive Ecosystem On Shore Of Hanfeng Lake

Recently,the urban environment constantly faced with the challenge of extreme weather disasters caused by global climate change,which reflects the irrationality of urban planning.As a new water management with integrated functions,the WSUD(Water Sensitive Urban Design)gradually becomes a hotspot of urbanization research.The WSUD is equipped with water management functions such as peak-flow reduction,pollution purification and water resource utilization.Besides,it plays a vital role in maintaining urban biodiversity,adjusting urban microclimate and reducing the urban heat island effect.As a newborn reservoir formed by Three Gorges Dam,the wetland type of Hanfeng Lake changes from river wetland to lake wetland,which changes the hydrological characteristics a lot,and becomes a huge challenge to the healthy development of the aquatic ecosystem.This thesis is made to ensure the water quality of Hanfeng Lake,to protect and improve the habitat of living beings,to protect and restore the biodiversity of the urban ecosystem.Based on the theoretical discussion,case study design and benefit evaluation of WSUD at home and abroad,this thesis aims to assess the ecological function of water sensitive ecosystem on shore of Hanfeng Lake scientifically.This thesis summarized the key technology of water sensitive ecosystem,to provide theoretical basis and practical guidance to optimize the design and management of water sensitive ecosystem,to explore the ecological mechanism to maintain biodiversity of water sensitive ecosystem,to optimize the ecological environment quality of Kai County,and build a livable water sensitive city and a sustainable development city.The main results of this thesis are reflected in:(1)An investigation was made on vascular plant diversity in thewater sensitive ecosystem(the experimental area)and artificial grassland(the control area).A total of 259 species of vascular plants were investigated,belonging to 76 families and 200 genera.In the experimental area and control area,the rate of single-species families and the monotypic genera is high,the dominate plants are herbs.Compared with the early stage,the plant species of different water sensitive structures in experimental area and control area both increase significantly.(2)An investigation was made on bird diversity in the experimental area and control area.A total of 314 birds were investigated,belonging to 27 species,19 families and 4 orders.In experimental area,Phoenicurus auroreus,Spodiopsar cineraceus and Lanius schach were the dominant species,and the dominant species changed in different season.In control area,Prinia inornata,Motacilla alba,Lonchura striata and Phoenicurus auroreus were the dominant species,the dominant species changed in different season.The species richness,abundance and Shannon-Wiener index of experimental area were higher compared with control area,and reached the highest value in autumn,when the food was most abundant.The main avian feeding functional group of experimental area and control area were both insectivore,relative abundance and richness increased with the season.Compared with traditional urban green space,water sensitive ecosystem is equipped with more complicated vegetation structure,higher habitat heterogeneity and more abundant food,which are vital for avian diversity.Contrast,avian promotes the sound development of urban ecosystem via seed dispersal and injurious insects predation.Finally,to increase biodiversity of urban ecosystem,it’s necessary to enlarge the use of water sensitive ecosystem.(3)An investigation was made on butterfly diversity in the experimental area and control area.A total of 862 butterflies were investigated,belonging to 30 species,22 genera,and 6 families.In experimental area,Graphium sarpedon,Pieris canidia,and Symbrenthia liaea were the dominant species,and the dominant species changed in different season.In control area,Pieris canidia and Pseudozizeeria maha were the dominant species,and appeared little change in different season.The butterfly richness,abundance and diversity index of experimental area were higher compared with control area,and reached the highest value in spring and summer,as nectariferous plants blooming.Compared with traditional urban green space,water sensitive ecosystem is equipped with more complicated vegetation structure and higher habitat heterogeneity,which are vital for butterfly diversity.(4)An investigation was made on litter-layer insect diversity in the experimental area and control area.A total of 10754 litter-layer insects were investigated,belonging to 7 classes,20 orders.In experimental area,Diptera and Hymenoptera were the dominant orders.In control area,Collembola,Hymenoptera and Diptera were the dominant orders.The average abundance of every water sensitive structure in the experimental area from high to low is,rain garden,insect hotel,living roof and living wall,and all reached the maximum value in autumn.The Shannon-Wiener index and Pielou evenness index of experimental area were all lower than control area.In experimental area,diversity indexes from high to low is,living wall,rain garden,insect hotel and living roof.The diversity indexes decrease from spring to summer,increase from summer to autumn,and reach the maximum value,then decrease from autumn to winter.