硅藻群落指示的近50年来大理西湖湖泊生态系统演变规律  

Sedimentary Diatom Records Reveal the Succession of Ecosystem in Lake Xihu,Dali over the Past 50 Years

作　　者：张晨雪 徐敏[2] 董一凡 王荣[2] 方凤满 ZHANG Chen-xue;XU Min;DONG Yi-fan;WANG Rong;FANG Feng-man(School of Geography and Tourism,Anhui Normal University,Wuhu 241003,China;State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]安徽师范大学地理与旅游学院,芜湖241003 [2]中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室,南京210008 [3]中国科学院大学,北京100049

出　　处：《环境科学》2020年第10期4572-4580,共9页Environmental Science

基　　金：国家重点研发计划项目(2017YFA0605203)。

摘　　要：近年来,增强的人类活动使得云南部分湖泊生态系统发生退化,由草型清水态向藻型浊水态转变.全球变化背景下,了解湖泊生态系统演变规律是进行有效管理的前提,具有重要的科学意义.本研究以云南大理州小型浅水湖泊西湖为例,通过对沉积物硅藻群落和理化指标的分析,探讨了20世纪60年代中期以来大理西湖环境演变历程.结果表明,大理西湖生态系统在近50年发生了明显的稳态转换,以2000年为节点,硅藻群落从2000年前偏好贫营养环境的底栖附生种Cocconeis placentula、Staurosira construens、Gomphonema angustum和Achnanthidium minutissimum为优势种的状态,逐渐演替为偏好中营养环境的底栖附生硅藻Encyonopsis microcephala和Navicula cryptocephala及偏好富营养环境的浮游硅藻Cyclotella atomus、Cyclotella meneghiniana、Stephanodiscus hantzschii和Aulacoseira granulata为主导的状态.时间序列的主成分分析表明,硅藻群落主要响应了营养的变化.冗余分析结果也证实营养盐富集是大理西湖硅藻群落长期演化的主要驱动因素.本文论述了近50年来大理西湖流域气候变化和开发活动(农业围垦、化肥施用、畜牧养殖和渔业养殖等)促使湖泊营养盐持续积累,浮游藻类大量繁殖,湖泊内部生产力显著提高,湖泊生态系统逐渐向藻型浊水态转变的演化特征.In recent decades,intense human activities have caused a decline in many lake ecosystems in Yunnan Province,rendering the transformation of the lake from a clear macrophyte-dominated state to a turbid phytoplankton-dominated state.Improved understanding of the ecological changes in lake ecosystem has significant implications for management.In this study,a small lake in Dali Prefecture of Yunnan Province,i.e.,Lake Xihu,was selected.Combined with diatom records and physicochemical proxies from the lake sediments,this paper focuses on the long-term ecological changes in Lake Xihu,Dali since the mid-1960 s.The results show that the Lake Xihu,Dali has undergone a significant shift in stable states over the past 50 years.Prior to 2000,the benthic-epiphytic species(i.e.,Cocconeis placentula,Staurosira construens,Gomphonema angustum,and Achnanthidium minutissimum)dominated in diatom assemblages,indicating oligotrophic conditions;since 2000,benthic-epiphytic species(i.e.,Encyonopsis microcephala and Navicula cryptocephala)and planktonic species(i.e.,Cyclotella atomus,Cyclotella meneghiniana,Stephanodiscus hantzschii,and Aulacoseira granulata)dominated successively,indicating mesotrophic to eutrophic conditions.Principal component analysis based on the diatom assemblages in temporal scale showed the response of diatoms succession to nutrients.Redundancy analysis also confirmed that nutrient enrichment was the main driving force for the succession of diatom assemblages in Lake Xihu,Dali.In the past 50 years,climate change and human activities(i.e.,agricultural reclamation,fertilization,animal husbandry,and fishery)have enhanced the accumulation of nutrients in the lake.The continuous loading of nutrients promoted the propagation of planktonic algae,and also the productivity of the lake,rendering the transformation to a turbid phytoplankton-dominated state.

关 键 词：大理西湖 浅水湖泊 硅藻群落 稳态转换 生态系统 

分 类 号：X524[环境科学与工程—环境工程]