大坝截流前后金沙江观音岩水电站鱼类群落功能多样性的变化

人类活动通过对非生物因素和生物多样性的作用从而对生态系统功能产生了巨大的影响。大量的理论和实验研究表明,物种功能性状在连接群落组成改变和生态系统进程转变中起着重要作用。由于物种功能性状的差异,栖息环境改变后,群落中容易适应新环境的物种占据优势,难以适应的物种数量减少甚至消失,从而导致整个群落结构发生改变,进而使整个生态系统进程发生转变。通过评价金沙江观音岩水电站大坝截流前后鱼类群落组成情况,结合不同种类功能性状的差异,采用生物多样性评估方法和功能多样性指数分析方法两种不同手段,对比分析截流前后大坝下游鱼类群落结构和功能多样性的变化,从而分析大坝建设的生态效应。结果表明:Bray-Curtis相异指数前后差异较大,辛普森指数无明显变化;功能多样性指数的变化表明大坝截流对水体中体型较大,口下位,食谱宽度较窄的鱼类生存和活动造成了一定的破坏,导致拥有这些特征的鱼类数量减少甚至消失,降低了下游鱼类群落的功能多样性,进而对该区域整个生态系统功能产生影响。

CHANGES OF FUNCTIONAL DIVERSITY IN FISH COMMUNITY BEFORE AND AFTER A DAM CLOSURE IN THE GUANYINYAN HYDROPOWER STATION

Human activities have strong impacts on ecosystem functioning through their effect on abiotic factors and on biodiversity.Classically,biodiversity changes have been assessed using diversity indices that take into account the number of species present (species richness) and the evenness of abundance distribution among species.However,such indices based only on taxonomic identity provide an incomplete view of biodiversity.Indeed,they do not take into account the biological identity and differences among species.While a lot of theoretical and experimental studies have shown that species functional traits play an important role in connecting changes in community composition and shifts in ecosystem processes.Based on this,we used two different methods,the traditional biodiversity assessment and functional diversity index,to analyze the change of ecosystem function before and after the dam closure of the Guanyinyan Hydropower Station.The purpose of this study is twofold:one is evaluation of the effects of the Ganyinyan Hydropower Station construction in the Jinsha River on the ecological system function,providing certain reference basis for the construction of water conservancy projects in the future,also laying a certain foundation for the author's next phase study.The second is through comparison and analysis to find a more effective and reliable method of assessing ecosystem function.Due to differences in functional traits of species,after habitat change,species that can adapt to new the environments will dominate in community,while species that can't adapt to the new environment will reduce the number or even disappear,leading to the community structure change,and thus make the entire ecosystem process shift.In this paper,by monitoring the fish community composition before and after the Guanyinyan dam construction,combined with the difference of fish functional traits,analyzed the changes of fish community structure and functional diversity before and after the closure of the dam,then make an evaluation of the impact caused by dam construction.Our results show that dam closure has caused some damages on the existence and behavior of the species with larger size,hypostomatous and narrow recipes width; resulted in a decrease in the number of or even disappear of the fish and reduced the functional diversity of fish communities downstream,and then a certain effect on the entire ecosystem function of this area.