【作者】 孙荣；

【导师】 袁兴中；

【作者基本信息】 重庆大学 ， 环境科学， 2010， 博士

【摘要】 河岸带是河流生态系统不可缺少的组成部分,是陆域高地集水区与河流水体之间的生态界面。河岸植被是河岸生态系统的重要组成部分,决定着河流生态系统的许多重要生态过程。对河岸植被的研究,不仅有助于进一步深化河流生态学理论,而且对河流生态系统及生物多样性保护具有重要的现实意义和应用价值。本文以三峡水库腹地的澎溪河流域为研究对象,在对河流等级体系及空间尺度划分的基础上,探讨了不同等级河溪河岸植物群落特征、河岸植被的空间格局、及其与环境因子的关系;本文还特别关注了山地河流水电开发对河岸植被的影响、以及水位变动下河岸植物群落物种丰富度格局的变化。本文的特色是以“3S”技术、植被生态学、生态水文学、生态空间理论的知识体系为背景,注重多学科交叉,对不同等级空间尺度下河岸植物群落特征、河岸植被与水电开发、河岸植被与水位变动,以及河岸植物群落对环境干扰的响应进行研究。主要研究结果如下。1.河溪空间分布格局的研究,能够为河流开发、保护与管理提供帮助。本文以澎溪河流域1:1万地形图为底图,在ArcGIS 9.0下提取流域河网,对河流等级体系与海拔、坡度以及区域植被覆盖情况进行了分析,并结合现场调查划分澎溪河流域的河溪体系。结果如下:(1)澎溪河流域划分为7级河溪系统。1级河溪的数量和长度均超过总量的50%,是流域河网主要的构成成分。(2)随河溪等级的增加,河溪分布的海拔范围和平均海拔都呈下降趋势,坡度范围和平均坡度也呈下降趋势;(3)随河溪等级的增加,河岸缓冲区内NDVI指数逐渐降低,反映出随河溪等级的增加,河岸植被受到外界干扰的增加,植被生长力逐渐下降;(4)综合分析河溪与海拔、坡度及NDVI指数的关系后,结合现场调查的结果,定义澎溪河流域1~3级为溪,4~7级为河。2.本文采用植物群落学调查方法,对澎溪河河岸植物群落特征进行了研究。结果表明:(1)河岸植物中共有维管植物151科470属859种,其中蕨类植物23科31属59种,裸子植物7科11属14种,被子植物121科428属786种,植物种类较为丰富;三峡水库蓄水影响的澎溪河下游河段共有维管植物79科188属227种,蕨类植物19科22属25种,被子植物60科166属202种;单种科、少种科、单型属、单种属和少种属在植物区系组成中占比例较大,体现了河岸带生境条件恶劣,植物群落组成的独特性。(2)植物生活型构成以草本植物为主,共540种,占总种数的62.87%;其次,灌木224种,占总种数的26.08%,乔木95种。受三峡水库蓄水影响的澎溪河下游河段河岸植物生活型组成充分体现了三峡水库蓄水后河岸带由陆生生态系统向湿地生态系统演替的趋势,227种植物中,水生草本107种,陆生草本97种,乔木6种,灌木17种。(3)区系地理成分复杂多样。科的分布区类型中,世界分布、泛热带分布和北温带构成植物区系的主体,分别占总科数的34.38%、25.78%、12.50%;属的分布区类型中,温带成分200属,占总属数的45.55%,热带成分178属占40.55%,反映出植物群落的过渡性。澎溪河河岸植物群落组成充分体现了澎溪河中亚热带向北亚热带过渡地区的特点,植物混杂现象较为突出,植物群落组成中珍稀、古老、孓遗、特有植物较多,体现出河岸带生境条件复杂,维持了较高的生物多样性。3.为研究河溪等级体系对河岸植被的影响,对澎溪河干流上游东河流域1~6级河溪河岸植被进行研究,对相关环境因子和河岸植物多样性进行分析。结果表明:(1)各环境因子随河溪等级的变化而变化。(2)总的物种丰富度、灌木层、草本层和草本样方的物种丰富度沿河溪等级增加先升高后降低的趋势,乔木层物种丰富度和灌木样方物种丰富度随河流级别增加逐渐下降。(3)植物群落多样性、优势度和均匀度随河溪等级的变化而变化。进一步分析表明,河溪等级变化对河岸生境、河岸植物群落多样性以及外界干扰都产生影响,因此,在进行河岸植被管理时应按照河岸植被的空间分布规律,也就是河岸植被在不同河溪等级上的分布情况,对不同的河溪级别实施针对性的河岸植被管理战略,即河岸植被分级管理策略。4.采用双向指示种分析法(TWINSPAN)和去趋势典范对应分析法(DCCA),以澎溪河干流上游东河为研究对象,从植物种、植物群落与环境因子之间的相互关系,对河岸植物群落的生态梯度进行研究。结果表明:(1)TWINSPAN分类将42个样地划分为15个群丛,其中森林类型4个,灌丛和灌草丛11个,植物群落具有明显的次生性,表明河岸带受到人类活动的干扰。(2)DCCA排序较好的揭示了河岸植物群落分布格局与海拔、河岸坡度、坡向、河岸宽度、底质类型、底质异质性、河流宽度、河流级别等自然环境因子和人为干扰的关系。进一步分析表明,海拔和人为干扰是影响河岸植物群落结构及分布格局的主导因子,河流宽度、河岸宽度、底质异质性和河流级别对河岸植物群落特有也有一定的影响。(3)结合环境因子的相关关系和DCCA排序结果,海拔对河岸植物分布起决定作用,其次是人为干扰、河岸宽度、河流宽度、河溪级别。研究表明,河岸植物群落在具有明显的沿海拔梯度变化的垂直梯度格局;沿河流纵向和侧向梯度变化,河岸植物群落具有典型的“片段化”分布格局;从植物群落物种组成和群落类型看,河岸植物群落是典型的次生植物群落。5.以澎溪河上游白里河、小圆河、满月河上三个小型引水式电站为对象,研究山地河流水电开发对河岸植被的影响,从而为水电开发影响下的河岸植被管理提供帮助。结果表明:(1)水坝上下游共发现维管植物125种,乔木14种,灌木30种,草本71种,其中湿生植物27种。(2)植物群落特征(物种丰富度和植物群落盖度)在河流之间和水坝上下游河段之间都存在显著的差异;不同溪流之间植物群落的差异性大于同一溪流的水坝上下游的植物群落。表明水坝建设已经导致河岸植物群落发生变化,但水坝导致的变化小于河流之间自然属性差异导致的变化。(3)从植物群落组成成分看,水坝下游出现了一些典型的旱生和属于周边高地植被的植物种类,如柏木(Cupressus funebr)等,水坝上游河段出现了耐水淹、抗冲刷的植物种类,如满江红(Azolla imbircata)、尼泊尔蓼(Polygonum nepalense)等。6.三峡水库蓄水淹没是澎溪河干流河段面临的主要干扰因素,三峡水库“蓄清排浑”的运行方式在三峡水库库周两侧形成垂直落差30 m,“冬水夏陆”的水位变动带,植物群落的组成、群落特征及空间格局都受到影响而发生变化。为了解三峡水库173 m蓄水后消落带植物群落的空间分布格局,探讨消落带生物多样性维持的生态学机制,在澎溪河消落带,沿河流纵向梯度和侧向梯度调查分析了植物群落物种丰富度以及物种丰富度与淹水时间、底质类型等环境因子的关系。结果表明:(1)在河流纵向梯度上,消落带植物物种丰富度、灌木层物种丰富度和草本层物种丰富度沿河流纵向梯度均表现出相似的格局特征,利用抛物线方程拟合,物种丰富度与到达河口的空间距离呈显著相关。(2)沿河流侧向梯度,总物种丰富度和草本层物种丰富度随高程增加先升高后降低;乔木层物种丰富度和灌木层物种丰富度随高程升高而增加。(3)相关分析表明,在河流纵向梯度上,物种丰富度随底质类型增加而增加。在河流侧向梯度上,物种丰富度与土壤水分、底质异质性相关性明显。研究表明,在河流纵向梯度上,距河口的空间距离对消落带植物物种丰富度具有重要控制作用;河流侧向梯度上,淹水时间、土壤水分和底质异质性对植物群落的分布格局有重要影响。研究表明在三峡水库173 m蓄水以后,消落带植物群落物种丰富度格局与天然河流河岸植被仍有类似的变化规律,但由于水位的季节性变动,已经开始形成自己独特的变化格局。7.以澎溪河一级支流白夹溪为例,通过样地调查和室内分析,研究了河岸植被与土壤理化因子的关系。结果表明:(1)聚类分析将河岸划分为5个不同的高程带,代表了5个不同的微生境。高程155-160 m的物种丰富度和Shannon-Wiener指数明显高于其他高程带,高程小于150 m的区域物种丰富度和Shannon-Wiener指数都是最低的。(2)单因素方差分析表明,在不同的生境条件下,土壤理化因子差异显著。(3)相关分析表明土壤类型、土壤异质性、土壤湿度和土壤速效钾含量都显著影响河岸植物物种丰富度和Shannon-Wiener多样性;Shannon-Wiener多样性还与土壤pH显著相关。更多还原

【Abstract】 Riparian plant community is an important part of riparian ecosystem, which comprises a broad assemblage of diverse forms, various vegetation types. The riparian ecosystem is an important core in the wetland ecosystem of river, in which the riparian plant community contributes to the production and creation, and determines many significant ecological processes in the river ecosystem. Study on riparian plant community not only helps deepen the theory of riparian ecosystem, but also has important vital meanings and application value of protecting the river environment and biodiversity.Plant communities in riparian zone are influenced by spatial scale, different types and degrees of natural disturbance and human disturbance. With an eye to forward field of international riparian ecological research, character of riparian plant communities, the relations between riparian plant communities and hydropower development, impoundment of Three Gorges Reservoir (TGR), and the responses of riparian plant communities to different disturbance were studied at different spatial scales in Pengxihe River watershed, based on the knowledge of‘3S’, geography, vegetation ecology, environmental science. Major conclusions of this research are as follows:1. Study on spatial pattern of river hierarchy could be help to river development, conservation and management. The structure of watershed and streams of Pengxihe River were modeled with 1:10 000 topographic map under ArcGIS 9.0. The spatial distribution of different order was studied with the elevation, slope and NDVI data. The results showed that:(1) A seven hierarchy established in Pengxihe watershed, with first order streams contributing up to 50% of the watershed. (2)Altitude change range, average elevation, slope change range and average slope decreased with steam order. (3) NDVI index increased with the stream order, which meant the vegetation around lower order’s stream was better than that of higher order’s ones. (4) Combined the relation of height, slope, NDVI index and hierarchy of river with field investigation, grade 1 to 3 were considered to be XI which, in comparison with HE (grade 4 to 7). Synthesize the hierarchy of streams and NDVI, the stream orders well reflected the disturbance degree and disturbance types well, from weak to strong, from natural to human.2. Based on field observation, the species composition, life-form and flora were studied. The results showed: (1) There were 859 species of riparian zone, which belongs to 470 genera and 151 families, in Pengxihe River. Among them there were 25 species, 31 genera and 23 families of pteridophyte, 14 species, 11 genera and 7 families of gymnosperm, and 786 species, 428 genera and 151 families of angiosperm. Onotypicand families, oligotypic families, monotypic genus, onotypic and oligotypic genus took larger proportion in the composition of the families and genuses. This indicated the severe condition and the unique of plants in riparian zone. (2) Herb species were the dominant groups, possessed 62.87% of the total species, with 95 trees and 224 shrubs. A total of 227 species of vascular plants were recorded in the water-level-fluctuation zone, among which there were 107 hygrophyte, with 97 land herbs, 6 trees and 17 shrubs. (3) The floristic analysis showed the geographical element was complex. For family, cosmopolitan, tropic to temperate types were 34.38%、25.78%、12.50% of the total families, respectively. For genus, there were 200 genera belonging to temperature type, 178 genera belonging to tropic type, which showed the transitional characteristics of riparian plant. Composition of plant community fully reflected the transitional characteristics from subtropical to north subtropical zone in Pengxihe watershed. Richness of endemic or relic plants indicated the old-growth and relictual characteristics of riparian plant communities.3. In order to know the effect of stream orders on riparian plants, a total of 34 sampling sites were conducted along the Donghe River continuum from 1st order to 6th order in the upstream of Pengxihe Watershed. The results showed: (1) Environmental factors (altitude, riparian slope, riparian width, river width, substrate heterogeneity and human disturbance) among stream orders had significant differences. (2) Among stream orders, species richness showed remarked difference. Total species richness, shrub species richness, herb species richness and herb quadrat species richness rose firstly and dropped afterwards; tree species richness and shrub quadrat species richness decreased with stream order increase. (3) Shannon-Wiener diversity, Simpson dominance and Pielou uniformity showed significant difference with stream orders; Shannon-Wiener diversity rose firstly then dropped afterwards. Further analysis showed that stream orders had a significant impact on riparian habitats, riparian vegetation and disturbances. This meant that riparian vegetation experienced different types and degrees of disturbance in different stream orders, so the Hierarchical Management Strategy(HMS) should be applied to riparian vegetation management.4. Based on the methods of TWINSPAN and DCCA, this paper studied the ecological gradients of the plant communities in Donghe River, in terms of the interactions between plant species and communities and environmental factors. The results showed that: (1) Based on TWINSPAN, 42 sites were classified into 15 associations, of which, 4 associations were forest communities, 11 were shrubs and herbs. All of the associations appeared the characteristic of secondary vegetation types, represented the different human disturbance intensity. (2) DCCA ordination revealed the relationships between the distribution patterns of the plant communities and the environmental components (altitude, riparian slope, aspect, riparian width, substrate type, substrate heterogeneity, stream width, stream order and human disturbance). The dominant factors controlling the distribution patterns of the plant communities were altitude and human disturbance, while riparian width, river width and stream order also had effects on the community characteristics. (3) Combined the correlations among environment factors with the results of the DCCA ordination, the most important factor affecting plant distribution in riparian zone was altitude, which was followed by human disturbance, riparian width, river width and stream order. Synthesize the results of TWINSPAN and DCCA, the riparian plant communities showed the following characteristics: along the elevation gradient, plant communities had significant altitudinal gradient; along longitudinal and lateral gradients of river, pattern of plant communities presented‘fragmentation’. The composition and types reflected that the riparian plant communities were typical secondary plant communities.5. The effects of hydropower development on riparian vegetation were studied along along upstream and downstream reaches of three hydropower reservoirs on the Baili River, Xiaoyuan River, and Manyue River. The results showed that: (1) 125 plant species in a total of 216 quadrats were recorded, with 4 trees, 30 shrubs and 71 herbs. (2) There were significant differences on plant communities (species richness, species cover) amongst rivers, the upstream versus downstream, with amongst rivers had larger differences. This suggested that the dams had led to changes in riparian plant communities, but difference caused by reservoir was within the natural range of variation found across the rivers. (3) We found some xerophytes and highland plants significant increased downstream of dams, such as Cupressus funebr, and some adaptation to tranquil reaches and lakes species significant increased upstream of dams, such as Azolla imbircata, Polygonum nepalense. This revealed that the construction of dams had changed the riparian habitat and the composition and diversity of riparian plant between downstream and upstream of dams.6. In order to understand the spatial pattern of plant community and the maintenance mechanism of biodiversity in littoral zone of Three Gorges Reservoir, 110 km stretches of Pengxihe River (from estuary to the backwater of Three Gorges) were chose to study. We investigated species composition and environmental variables along 50 m long stretches of riverbank between the high-water level and the lowest summer water level, with a 5 km interval. The results showed that: (1) along longitudinal gradients, longitudinal species richness, longitudinal shrub species richness and longitudinal herb species richness were significantly related to distance to estuary; (2) along lateral gradient, there were visible different changes in all kinds of types (lateral species richness, lateral tree species richness, lateral shrub species richness, lateral herb species richness).Along lateral gradient, species richness and herb species richness increased with the elevation then reduced, trees and shrubs species richness increased with the elevation. (3) Correlation analyses showed that substrate types were correlated with the longitudinal species richness, without considering the distance to estuary. Soil moisture and substrate heterogeneity were correlated with lateral, species richness. These results indicated that, along longitudinal gradient of the river, distance to estuary played an important role in species richness, while along lateral gradient spatial heterogeneity due to inundation and flooding played an important role in forming a new pattern of plant community in the littoral zone of Three Gorges Reservoir Region. Because of special hydrological dynamics, plant in the littoral zone of Three Gorges are gradually form a unique spatial pattern to some extent, although it had the same change law with riparian plant of a natural river.7. In order to find out the relationship between riparian communities and soil properties in Three Gorges Reservoir after its initiate impounding to 173 m height, plant community was investigated in the riparian of Baijiaxi Stream. Based on field survey and laboratory experiment, plant diversity and soil properties were studied. The results showed that: (1) Riparian zone was divided into five habitats with different heights, which well reflected the water level changes from 145 m to 175 m. Between 155 m to 160 m, results showed the highest species richness and Shannon-Wiener diversity, with the lowest appeared at less than 150 m area. (2) Among different habitats, soil properties showed significant differences. (3) Correlation analysis showed that the species richness and Shanon-Wiener diversity index was influenced by soil heterogeneity, soil type, soil moisture, soil available potassium.更多还原