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题名: 浅水湖泊生态系统的草-藻型稳态特征与稳态转换研究
作者: 常锋毅
答辩日期: 2009-06-03
导师: 刘永定
授予单位: 中国科学院水生生物研究所
授予地点: 水生生物研究所
学位: 博士
关键词: 浅水湖泊 ; 富营养化 ; 沉水植物 ; 浮游植物 ; 浮游动物 ; 沉积物 ; 稳态转换 ; 草型清水稳态 ; 藻型浊水稳态,NaOH提取态磷(NaOH-P),稳态转换阈值 ; 浮游藻类丰度比值
其他题名: Study on Lake Ecosystems and Regime Shift between Macrophytes-dominated and Algae-dominated States
摘要: 对于浅水湖泊而言,以沉水植被为主要生物组分的草型清水稳态和以浮游植物为主要生物组分的藻型浊水稳态是生态系统稳态转换过程中的两个典型状态,并且各自具有不同的反馈机制维持其生态系统的稳定。从湖泊生态系统所能提供的服务功能来看,草型清水稳态湖泊对于人类社会所需求的资源与环境以及支撑社会经济活动具有更大的服务价值。但是,人类直接或间接的生产活动使我国很多浅水湖泊的富营养化程度加剧,并通过食物网的变化导致湖泊生态系统由草型稳态向藻型稳态转变。笔者以滇池及14个湖泊为研究对象,在不同时空尺度下从湖泊生态系统理化特征、浮游植物、浮游动物、水生植物以及沉积物特性等方面验证了稳态现象,初步探讨了两类典型稳态的差异、维持机制和转换条件。主要研究结果如下: 1)研究了滇池水体不同区域的理化性状,比较分析了云南14个湖泊的水体理化性质,并分别分析了其各自的生态系统稳态特征,结果表明:滇池全湖营养分区明显,呈现从北向南依次降低的趋势;影响湖泊透明度的主要因素有总磷、叶绿素a和浊度,其中透明度随总磷增加而下降,当总磷浓度大于50μg/L,会导致透明度的急剧下降;叶绿素a、透明度以及浊度之间显著相关表明藻类水华是水体浊度增加的主要原因之一。同时,结果还表明:草型湖泊生物可利用态氮磷和颗粒态氮磷含量显著低于藻型湖泊,说明沉水植物在对水体营养物吸收和沉积物固定方面具有显著作用,成为草型清水稳态的重要先决条件。 2)比较了滇池不同湖区和14个不同状态湖泊不同时空尺度条件下,草型稳态和藻型稳态浮游植物的群落结构特征,结果表明:不同湖泊乃至中型湖泊不同湖区的浮游植物群落具有不同的周年演替规律,在北亚热带高海拔条件下,草型湖泊演替规律为硅藻-束丝藻-绿藻-微囊藻-硅藻,而藻型湖泊为束丝藻-鱼腥藻-微囊藻而后入秋冬季节后再到束丝藻;通过比较不同稳态湖泊浮游植物群落结构,发现蓝藻、绿藻和硅藻的不同群落丰度可以很好的指示湖泊稳态。 3)对滇池水生植被演替过程及现状进行了调查和分析,研究了不同稳态湖泊状况下的沉水植物,剖析了影响其生物量和物种多样性的主要因素,结果表明:湖泊沉水植物物种多样性与生物量显著相关,随着沉水植物种类数的下降,生物量相应地显著下降;而沉水植物生物量和物种多样性又密切与水-沉积物界面的生物可利用磷相关,随着生物可利用磷含量的增加湖泊水生植物生物量和多样性显著下降;因此,保持水体溶解性活性磷低于5μg/L,表层沉积物生物可利用磷低于60μg/L,有利于湖泊沉水植物群落生长与稳定。相反,当表层沉积物生物可利用了磷含量超过60μg/L时,上覆水溶解性活性磷变化较大,不利于沉水植物多样性保护与恢复。 4)对滇池草型湖区与藻型湖区以及14个湖泊的沉积物特征进行比较分析,结果表明:沉积物中对水体总磷和叶绿素a贡献最大的是铁铝结合态磷,并且沉水植物和浮游植物可以通过其生长活动影响沉积物中不同磷形态的含量;不同湖泊沉积物总磷(TP)浓度差异较大,而TP含量受多种因素的影响,因此以沉积物的TP作为指标不能准确区分两类稳态状况,而通过聚类分析以NaOH-P则可以有效区分两类湖泊。 5)确定总磷是湖泊生态系统稳态转换最主要的驱动因子,并采用分段函数法对滇池藻型和草型两类典型湖区转变的条件进行了探讨,发现草型区域总磷始终低于120μg/L,而藻型区域总磷始终高于150μg/L;对不同稳态的14个湖泊进行分析可以看出,湖泊草型向藻型稳态转换的阈值为70~110μg/L,而藻型向草型稳态转换的阈值为25~40μg/L。
英文摘要: For shallow lakes, macrophytes-dominated clear water and algae-dominated turbid water are the two typical states in the regime shift process of ecological systems. The two states have different feedback mechanisms to maintain the system stability. As to the lake ecological services concerned, macrophytes-dominated clear water is more valuable to environmental protection and production action than algae-dominated turbid water. However, with more and more effect of human activities, some lakes in China have been suffering eutrophication of different degrees and a big amount of shallow lakes shift from macrophytes-dominated clear state to algae-dominated turbid state following the change of food-net structure. In the present study, Lake Dianchi and the other 14 shallow lakes in Yunnan Province, South-west China were investigated in spatial and temporal scales to elucidate the difference and respective maintenance mechanisms of the two typical states with the characteristics analysess of various physic-chemical factors, as well as parameters of phytoplankton, zooplankton, aquatic plants and sediment. The main results are summarized as follows: 1) The physic-chemical characteristics were studied not only in different areas of Lake Dianchi but also in 14 lakes of Yunnan Province with different steady states. The results on Lake Dianchi showed that there were obvious divisions of trophic state in the Lake, and the trophic level decreased from north to south. Moreover, transparency in the Lake was mainly affected by total phosphorus, chlorophyll a and turbidity. While the total phosphorus increased, the transparency decreased; it decreased sharply when the concentration of total phosphorus reached up to above 50μg/L. In addition, the relationship of transparency with chlorophyll a and turbidity were significant, which indicated that algal bloom was one of the main causes to enhance the turbidity. Results of similar ananlysis on the other 14 lakes showed that in the macrophytes-dominated lakes there were significantly lower loads of biologically available nitrogen and phosphorus, as well as particulate nitrogen and phosphorus, than those in the algae-dominated lakes, which suggested that submerged plants played significant effects on nutrient uptaking and sediment fixation. 2) The phytoplankton characteristics in spatial and temporal scales of macrophytes-dominated lake were compared with those of algae-dominated lake. The results showed that lakes or regions with different steady states had different annual succession rules: the macrophytes-dominated lake had the succession rule of Bacillariophyta- Aphanizomenon- Chlorophyta- Cyanophyta, but the algae-dominated lake was Aphanizomenon- Anabaena- Microcystis which belonged to Cyanophyta. In addition, it was found that the abundances of Cyanophyta, Chlorophyta and Bacillariophyta were good index to evaluate steady state of lakes. 3) Analysis based on aquatic vegetation succession in different areas characterized with dominance of submerged higher plants or planktonic algae in Lake Dianchi, features of different steady states were studied to exame the main factors which determine the plant biomass and species diversity. Results showed that the species diversity of aquatic plants significantly correlated with the biomass, the biomass decreased obviously while the diversity decreased; further more, bio-available phosphorus in water and sediment was closely related to biomass and species diversity, and the biomass and diversity decreased prominently while the bio-available phosphorus increased. It means an important role played by the bio-available phosphorus in the growth and maintenance of submerged vegetation. Results also revealed that, when soluble reactive phosphorus (SRP) in the water column was below 5μg/L and bio-available phosphorus in sediment was below 60μg/L, the aquatic vegetation was stable. However, when the bio-available phosphorus in sediment was over 60μg/L and the soluble reactive phosphorus in water column become changing in a wide range it would be hard for vegetation protection and species diversity recovery. 4) Sediment characteristics were studies in different areas of Lake Dianchi and also in the investigated 14 lakes of different steady states. Results showed that the most contribution to total phosphorus and to chlorophyll a in water column originated in the NaOH-phosphorus; phosphorus fractions in sediment were affected by the growth activities of phytoplankton and aquatic plant; total phosphorus in sediment of different lakes varied widely and was affected by various factors, thus it is not employed to divide exactly the two typically steady states of lake ecosystem, but NaOH-phosphorus can be used to divide availably the two types of lake states with cluster analysis. 5) Results in this study explained that,total phosphrus is the most important nutrient factor in driving the regime shifts of lake ecosystems. Further results from study on shifts between the two typical regions in Lake Dianchi with the piecewise function method, showed that total phosphorus in macrophytes-dominated regions was always below 120μg/L, but in algae-dominated regions it was always over 150μg/L in the same lake. In addition, studies on lakes of different steady states explained the threshold of total phosphorus was 70~110μg/L in the shift process from macrophytes-dominated state to algae-dominated state, and the TP threshold was 25~40μg/L in the shift from algae-dominated state to macrophytes-dominated state.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ihb.ac.cn/handle/342005/12438
Appears in Collections:中科院水生所知识产出(2009年前)_学位论文

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Recommended Citation:
浅水湖泊生态系统的草-藻型稳态特征与稳态转换研究.常锋毅[d].中国科学院水生生物研究所,2009.20-25
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