重庆主城区滨江绿地生境质量研究——以夏季鸟类为指示类群

Study on the Habitat Qualities of Riverside Green Spaces in Central Districts of Chongqing:Taking Summer Birds as Indicators

河流廊道对城市化区域生物多样性保护至关重要。为探明重庆主城区滨江绿地生境质量,选择以夏季鸟类为指示类群,通过样线法对滨江区域20个绿地斑块进行了调查,并开展了群落相似性分析、聚类分析、物种多样性和指示种计算等相关分析。结果表明,研究区域雀形目鸟类占绝对优势,比例为78.12%,留鸟居多占71.88%;样地间鸟类群落结构相似性普遍较低,中等不相似和极不相似群落各占53.68%和23.16%;鸟类群落可聚为3类,分别对应受轻度、中度和重度干扰的3类生境;各干扰程度生境中鸟类多样性指数均较低,且在受不同干扰程度影响的生境间无显著差异;位于城乡边缘地带的重度干扰型生境中鸟类多样性指数均高于轻度干扰型;轻度干扰型生境指示种为白颊噪鹛和白头鹎,重度干扰型为麻雀。根据以上结果,重庆主城区滨江绿地鸟类生境普遍受到城市化影响。建议在未来的城市滨江空间建设过程中,应注重绿地生境修复和营造,并同时优化城乡边缘地带土地利用管理,保育优质绿地生境。

River corridors are essential for the preservation of biodiversity in urbanized areas.However,the ecological function of river corridors are often affected by diversified disturbances,such as flood prevention,water supply,landscape recreation,and improvement of urban traffic.To reveal those disturbances on habitat function,we selected the summer birds in the riparian zone of the two rivers and four banks in the main urban area of Chongqing as indicator groups,and investigated the bird community structures and biodiversities in 20 riverside green space patches by the line transect method.Meanwhile,environmental surveys were conducted in 20 sampling sites.Environmental elements including the area,width,plant composition,and human disturbance were recorded.The Bray-Curtis similarity index was used to analyze the similarity of bird community structure among sampling sites.Cluster analysis on the bird communities was conducted based on the Euclidean distance,and the results were used to indicate habitat types.The community similarity and cluster analysis were performed with statistical analysis software R.We hypothesized that:1) the similarity of bird community structures between most sampling sites should be high against the background of urbanization;2) the bird species and biodiversity in riverside green spaces would be generally low,but in areas such as remaining natural woodlands or riverside parks with good vegetation coverage might provide important habitats for birds,in which the species number and biodiversity were relatively high.Results indicated that the dominate species in the study area were the passerine,with a proportion of 78.12%.And the resident birds accounted for 71.88%.The similarity of the bird communities between sampling sites was generally low,with the medium dissimilarity accounting for 53.68%,the very dissimilar communities accounting for 23.16%,and the medium similar community accounted for 22.63%,while the very similar community accounted for only 0.53%.According to the cluster analysis (Fig.2),bird communities in the sampling sites could be classified into three categories at the Euclidean distance of 55,which were corresponding to bird habitat types under different interference levels (typeⅠ-mild interference,type Ⅱ-moderate disturbance,type Ⅲ-severe disturbance).The Margalef index and Shannon-Wiener index in severely disturbed (type Ⅲ) habitats were higher than those of the other two types of habitats,while the Simpson index and Pielou index in various habitats were not much different.Overall,there was no significant difference in species diversity index among the three habitat types.The dominant bird species in habitat type Ⅰ were white-browed laughingthrush (Garrulax sannio),(tree) sparrow (Passer montanus),and Light-vented Bulbul (Pycnonotus sinensis);in habitat type Ⅱ were white-browed laughingthrush,white wagtail(Motacilla alba),and Light-vented Bulbul;while in habitat type Ⅲ was (tree) sparrow.Species with the highest frequency in the sampling sites were white-browed laughingthrush and (tree) sparrow.Results of indicator species analysis showed that there were two indicator species in habitat type Ⅰ,which were white-browed laughingthrush and light-vented bulbul,and the indicate function of white-browed laughingthrush was extremely significant;(tree) sparrow was the only indicator species for habitat type Ⅲ;by contrast,there was no indicator species in habitat type Ⅱ.Sampling site groups classified based on cluster analysis of bird communities accurately reflected the habitat quality of each riverside green space.It illustrated that birds could be important indicator groups for evaluating the health status of urban river corridor ecosystems.Due to the degradation of habitat in the urban area,single riverside green space can only maintain biodiversity at a low level.Furthermore,riverside buildings and artificial structures blocked the communications between green spaces,which resulted in the differentiation of bird community structures and represented low similarities.Residual natural woodlands (such as S2 and S4) play a vital role in maintaining the diversity of urban birds,and those superior urban parks provide alternative habitats for effective preservation of bird diversities.It is concluded that urbanization has general impact on the bird habitats of riverside green spaces in the main urban area of Chongqing.Scientific and reasonable conductions in water system planning,vegetation community design,tree species selection,and human disturbance control will contribute a lot to improve riverside bird habitats.Meanwhile,in the process of urban development,we should pay attention to the protection of critical green space patches.It is wisdom to preserve habitats for birds in the process of developing green space planning.Moreover,supervision measures and coordination mechanisms in the urban development process should be strengthened.Besides,refining green space protection policies,strengthening the ecological redline control,and protecting the ecological background of mountainous environment are essential too.