【作者】 夏智勇；

【导师】 王力；

【作者基本信息】 西南大学 ， 生态学， 2011， 博士

【摘要】 消落带是陆地生态系统和水生态系统之间的过渡性生态系统,具有明显的环境因子、生态过程和植物群落梯度,是控制周边陆地和水域生态系统的关键区域。由于消落带生态系统具较高的敏感性和脆弱性,在三峡水库运行后,如何保护和恢复消落带植被,充分发挥其在固堤防灾、水土保持、营造优美景观等方面的生态功能,维持生态系统的良性循环,对三峡水库的正常运行有着十分重要的意义。消落带植被恢复的关键在于根据生境特点选择适生物种,建立稳定、多样的植物群落,对库区消落带现有植物、优势种群及其生境开展实地调查研究,掌握消落带生境特点及变化规律,分析现有物种和优势种群的区系沿革、生活习性和分布特征,是科学制定消落带植被恢复策略的前提和基础。2009年至2010年,《重庆市重点湿地生物资源调查与研究》课题组在三峡库区长江消落带,在巫山、奉节、丰都、忠县、云阳、开县、石柱、涪陵、江津等地,设置水平和垂直样带,对植物开展野外实地调查,记录植物种名、生活型特征、环境特征和多度等,对于不能现场判定的植物进行拍照,采集、制作标本,并带回实验室进行种类鉴定；根据水淹影响程度,在巫山、奉节、云阳、开县、忠县、丰都等地,以优势植物群落为研究对象,调查记录植物的株数、高度、盖度数据及小生境情况。运用统计学和相关软件进行数据统计分析,系统研究三峡水库消落带植物的区系组成特征、种群空间分布格局、优势群落分类和排序、群落物种多样性特点；分析消落带生境特点、环境影响因子及变化趋势,对消落带植被恢复对策和下一步研究重点进行了分析,得出以下几点结论：(1)根据本课题组野外调查统计,重庆三峡水库消落带共有种子植物466种,分属于78科、253属,其中裸子植物1科、2属、2种,被子植物中有双子叶植物60科、169属、297种,单子叶植物17科、82属、167种。消落带植物中草本植物占有绝对优势,单子叶植物占有相对优势,菊科、禾本科和莎草科种类最多,大型属较少,单种科、单种属较多。消落带植物区系在地理成分组成及其分布上都表现得相当复杂,既有热带、温带成分,又有东亚、地中海型等成分,间断分布在分布区类型所占比例较大。通过对野外实地调查资料的整理,课题组形成了《重庆三峡库区消落带维管植物名录》(附录1)。(2)应用TWINSPAN分类方法将50个样方划分成15个群丛、3种类型,从群丛所处的环境特征和分布位置来看,不同类型之间物种分布呈明显的环境湿度梯度变化。物种较少、地方特有成分缺乏、群落组成简单、以草丛植被为主的格局构成消落带植被的总体外貌和基本特征。消落带植物群落的DCA排序结果表明：植物群落类型的分布与生态环境的变化趋势相一致,第一排序轴反映出消落带水淹胁迫对植物的影响,从左到右水淹干扰的影响逐渐显著；第二排序轴则与土壤含水量以及建群种水生植物生活型关系密切,从上到下土壤环境依次为水淹潮湿土壤环境向干燥、多砾石环境过渡。消落带植物物种DCA排序结果显示,主要优势种在图上的位置基本与群落排序位置一致,说明水生植物群落在消落带的分布主要与优势种的空间分布特征密切相关。第一、二排序轴的特征值分别为0.884和0.718,(3)根据本课题组野外调查数据,本文选取了扩散系数(ID)、聚集度大小指数(ICS)、Green指数(GI)、聚集频度指数(ICF)、平均拥挤度指数(1MC)、聚块度指数(IP)、莫里西塔指数(IM)等7项指数,分析研究了重庆三峡水库消落带四个海拔区段的优势植物种群空间分布格局。结果表明：1)优势种群的聚集强度有差异,优势种群的优势度随水淹胁迫的降低而降低；2)种群空间分布格局在很大程度上受水淹胁迫的影响,但是水淹胁迫不是唯一的决定因素；3)在不同区段中,同一种群的聚集强度不同主要与环境条件有关；在同一区段中,各个种群的聚集强度不同与物种的生活习性关系密切；4)狗牙根种群在各海拔区段均为突出优势种群,与其耐水淹胁迫、耐旱、耐贫瘠的习性及根系发达、匍匐茎营养生殖方式有关。其他物种分布规律不明显。(4)消落带植物群落内α物种多样性研究表明,随海拔降低,水淹时间延长、水淹深度增大,水淹胁迫加强,相应的物种多样呈现明显的下降趋势,物种均匀度变化相对较小。以个体数目和以物种重要值为基础的物种多样性指数整体保持一致,采用物种重要值为基础的数据较稳定。物种丰富度测定上,Simpson多样性指数和Shannon-Wiener信息指数基本保持一致,Shannon-Wiener信息指数测度物种多样性更加灵敏,Simpson多样性指数相对稳定,以个体数目为基础的数据更敏感。物种均匀度测定上,Pielou指数和Alatalo指数基本保持一致,在物种总数较低的样地中,使用Pielou指数要强于Alatalo指数。(5)消落带植物群落间β多样性研究结果表明,随着海拔梯度的升高,水淹胁迫强度减弱及其他生境的变化,植物群落的物种数和总株数整体上呈增加趋势；植物群落的差异性增大,相似性减小,物种更替明显。消落带水淹胁迫因子对植物物种分布影响巨大,随着水淹胁迫加剧,植物分布种类减少。周期性的水位变化、土壤及营养流失、库区环境污染、大型工程建设、外来物种入侵等都会对库区生态环境造成强烈的冲击,威胁消落带的植物多样性和生态安全。为了科学有效地恢复重建三峡水库消落带植被、维持好植物多样性,确保库区生态安全,需要持续开展水体淹没对生态环境的改变和对植物生存影响的相关科学研究；切实加强对消落带植物资源,尤其是珍稀、特有和重要野生植物的调查和科学研究,采取有效措施加以保护。更多还原

【Abstract】 Water-level-fluctuating zone (WLFZ) is a transition ecological environment between terrestrial and aquatic ecosystems. In Three Gorges Reservoir Region (TGR), with the attractive characters of environmental factor, ecological processing and gradients of plant communities, WLFZ becomes the key system for controlling terrestrial and aquatic ecosystems. It is very important to keep the WLFZ ecological functions run smoothly after TGR operation, such as riverbank stabilization, soil conservation and creation of beautiful landscape, which will be very helpful to recover the WLFZ after the impoundment of Three Gorges Dam. For this purpose, we need to investigate the distribution and diversity of present plant communities, to confirm the dominant plant communities in this area, and to get the information for their living environment. With all these informaton, we can build a stable, varied plants database, which is the foundation for make the scientific strategy to recover the WLFZ after the TGR operation.From2009-2010, the project,’Research Work for Main Wetland Creatures Resource in Chongqing’, was investigated in Three TGR in9counties, Wushan, Fengjie, Fengdu, Zhongxian, Yunyang, Kaixian, Shizhu, Fulin, and Jiangjin. We investigated all the wild plants in WLFZ of the9counties. With setting typical plots and line-transit, all the plants information, such as plant name, their living characters, and their varied characters were recorded. For those we can’t identify in local area, we took the pictures, brought the plant samples back to lab to identify.To investigate the dominant plant communities in WLFZ in Wushan, Fengjie, Yunyang, Kaixian, Zhongxian, Fengdu,180plots were set depending on different water flood. We recorded all the information including plants’number, height, coverage, and their micro-living environment. We investigated the floristic composition, spatial distribution pattern, community classification, ordination and species diversity in these plots. Statistical software were performed to analysis data. The key conclusions of the study are as follows.(1) Based on field survey, in WLFZ of Three Gorges Reservoir Region (TGR) in Chongqing, there were466kinds of seed plants, which belong to78families,253genera. Among them, there were2species of gymnosperm, belong to1families,2genera. Herbaceous plant had an absolute predominance in WLFZ in TGR of Chongqing. In herbaceous plants, Compositae, Gramineae and Cyperaceae were the main families. In terms of genus, large genus was rarity, but single genera and specy was excessive. The geographical distribution and composition of flora in WLFZ was very complicated. The geographical composition of this area had many types, such as, tropic, temperate, Eastern Asian and Mediterranean. In geographical distribution, the disjunction distribution took a large proportion. With all the plants information we got from field survey, we built our database, Directory of Vascular Plants in Water-level-fluctuating zone of Three Gorges Reservoir in Chongqing (Appendix1). Directory of70Dominant Species in Water-level-fluctuating zone of Three Gorges Reservoir in Chongqing (Appendix2).(2) Based on the TWFNSPAN classification,50plots were divided into15associations, be classified as three types. The distributions of aquatic plant communities were consistent with the water in the environment which basically represented the major plant communities in water-level-fluctuating zone in the TGR in Chongqing. There were four wetland plants in these communities, submerged aquatic vegetation, emergent aquatic plants, and fixation of both floating-leaved aquatic plants and submerged, emergent aquatic plant. Aquatic plants communities can also be classified as three types, submerged plant community, fixed floating leaves community and emergent plant community. Emergent plant was the major community.We also analyzed the plants in WLFZ by Detrended Correspondence Analysis (DCA) compositor, the feature values of the first and second ordination axis were0.884and0.718, respectively. According the results, the distributions of aquatic plant communities were consistent with the water in the environment. The first ordination axis reflected basically the effects of water on aquatic plants which increased gradually from left side to right side. The second ordination axis reflected the close relationship of soil moisture and the life form of dominant aquatic plant species. The DCA compositor data showed that the main species had the same location on the species map and the community compositor ranks, which means the distribution of aquatic plant communities was closely related to the spatial distribution of dominant species. The ecological environment type and the gradient, which were reflected by the first and second ordination axis values, were corresponding with the DCA compositor data. These results were showed that the spatial distribution of plant species was very similar to the distribution of the communities.(3) We used7indexes to evaluate the spatial distribution pattern of dominant plant species, diffusion index (ID), aggregation index (ICS), green index (GI), aggregation frequency index (ICF), mean crowding index(IMC), poly-block index (IP) and Maurice west index (IM). The results showed that,1) the distribution of all dominant species had different aggregation intensity, the lower threaten of fluctuating water flood, the lower dominance of dominant species.2) The spatial distribution pattern of plant species was affected by fluctuating water flood, but which is not the only reason.3) In different section, same plant species had the different aggregation intensity, which mainly related to the local environments. In same section, different plant species had different aggregation intensity, which related to their breeding habits.4) In each altitude section, Cynodon dactylon community was the dominant species, because of its tolerant ability to flood, drought, and soil leanness, and with abundant root mass, nutritional reproduction method. The distribution pattern of other species was not obvious.(4) The analysis of a-diversity in plant communities showed that species diversity mainly affected by flood seasonal in WLFZ in the TGR. With lower elevation, longer and deeper flood, there were greater flood disturbance to the species diversity, which showed a downward trends significantly. Comparisons of various indices of species diversity, the results were concerted among species richness, Simpson diversity index and Shannon-Wiener information index, but the species evenness index was had little difference. To analysis species evenness, Pielou evenness index and Alatalo index stayed the same. Otherwise, to analysis the plots with less species, Pielou index was much better than Alatalo index. The results in good agreement between Simpson diversity index (SDI) and Shannon-Wiener information index (SWI) analysis. SWI was more sensitive than SDI to species diversity analysis, but SDI was more stable than SWI because of the species evenness. Species diversity index which based on the number of individuals and the important value of species stayed consistent in practice, but it was better to use species diversity index which based on the important value of species. Whereas, for species richness analysis, it was better to use species diversity index which based on the number of individuals.(5) The analysis of (3-diversity for plant species of WLFZ in TGR showed that the number of plant species and overall number of plants increased with the altitude elevation, the flood threaten decrease, and other changes in living environments, and accompanied by increased plant species diversity, decreased species similarity, and species alternation.The plant species distribution in WLFZ can be influenced strongly by fluctuating water flood. The more fluctuation flood, the less plant species. The ecological environments in TGR can be affected by many factors, including cyclically water-level changing, soil and its nutrition running off, environmental pollution, and large facilities construction. Further, the plant diversity and ecological safety can be threatened by those consequences. In order to recover the plant cover and to protect the plant species diversity in WLFZ in TGR, we need to keep doing the scientific research work on the effects of flood water on the ecological environment and plant living. We also need to investigate the plant resources and wild plants in this area, especially the rare, unique and key wild plant species, to take corresponding countermeasures on protecting the plant resources in WLFZ in TGR.更多还原