Knowledge Resource Center for Ecological Environment in Arid Area
| 青藏高原高寒荒漠和草原的分布格局及群落特征 | |
| 其他题名 | The distribution patterns and community characteristics of the alpine desert and steppe on the Tibetan Plateau |
| 赵海卫 | |
| 出版年 | 2017 |
| 学位类型 | 博士 |
| 导师 | 郭柯 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 青藏高原是全球变化的敏感地带，植被及生态系统相对脆弱，关注青藏高原的植被现状和动态对维护该区域的生态安全具有重要意义。高寒荒漠是青藏高原西北部及其周边高地特有的荒漠类型，并以垫状驼绒藜(Ceratoides compacta)高寒荒漠分布范围最广、最为典型，而各类针茅草原几乎遍布青藏高原整个草原区，是青藏高原最具代表性的草原类型。受青藏高原特殊自然环境条件的限制，高寒荒漠和资料匮乏区分布的针茅草原考察研究较少，其群落类型、分布格局及群落特征尚不明确。本研究对羌塘高原及雅鲁藏布江上游谷地等资料匮乏区分布的垫状驼绒藜高寒荒漠和针茅草原进行了实地调查，其中垫状驼绒藜高寒荒漠样地33个，各类针茅草原样地79个，结合样地气候等环境数据，分析研究了垫状驼绒藜高寒荒漠的分布和环境特征；并采用非度量多维尺度分析(NMDS)对所调查的针茅草原类型进行了数量验证，同时运用去趋势对应分析(DCA)和去趋势典范对应分析(DCCA)等数量生态学方法，分析研究了青藏高原资料匮乏区针茅草原的气候分布格局，通过分析计算青藏高原资料匮乏区一手的群落调查数据，对垫状驼绒藜高寒荒漠和11类针茅草原的群落特征进行了定量研究，包括其群落物种组成和数量特征。主要结论如下：(1) 垫状驼绒藜高寒荒漠的分布既有高原地带性的特征，又受到局部地形、土壤水分及化学性质的强烈影响而表现出一定隐域性的特点；垫状驼绒藜高寒荒漠群落盖度稀疏且变化较大，植物种类贫乏，菊科、禾本科、十字花科、豆科、藜科植物在其物种组成中扮演着重要角色，属的分布区类型多为北温带分布，占63.8%；寒、旱、盐碱、贫瘠是垫状驼绒藜高寒荒漠的四大环境特点，其中干旱既有气候性的干旱，又有生理性的干旱。(2) 青藏高原资料匮乏区调查的针茅草原经NMDS分析验证共分为11类，其中单优种群落9类，包括羽柱针茅(Stipa subsessiliflora var. basiplumosa)群系、紫花针茅(S. purpurea)群系、疏花针茅(S. penicillata)群系、丝颖针茅(S. capillacea)群系、大紫花针茅(S. purpurea var. arenosa)群系、沙生针茅(S. glareosa)群系、戈壁针茅(S. tianschanica var. gobica)群系、昆仑针茅(S. roborowskyi)群系和东方针茅(S. orientalis)群系；共建种群落2类，分别为紫花针茅+羽柱针茅(S. purpurea + S. subsessiliflora var. basiplumosa)群系和紫花针茅+昆仑针茅(S. purpurea + S. roborowskyi)群系，其中疏花针茅群系、大紫花针茅群系和两个共建种群系为新增群系类型。青藏高原资料匮乏区针茅草原类型虽然多样但不均衡，主要类群较为有限。 (3) 青藏高原资料匮乏区针茅草原群落DCA分析表明，水分梯度是影响针茅草原物种和群落变化的主要潜在环境梯度。用样地降水相关的气候因子作为解释变量进行DCCA分析，结果表明降水尤其是最湿月降水是影响针茅草原群落变化及分布格局的主要气候因素。主要针茅草原类型中，羽柱针茅草原和沙生针茅草原通常分布于干旱的生境中，但羽柱针茅草原各样地降水差异较大。相比之下，昆仑针茅草原和丝颖针茅草原降水较多。紫花针茅草原和昆仑针茅草原样地间的降水差异较大，这说明两类针茅草原对水分条件的耐受性较强，这两类针茅草原在青藏高原资料匮乏区的分布范围都很广。(4) 青藏高原资料匮乏区针茅草原样地共出现物种150种，归为80属，25科。其中禾本科、菊科、豆科、莎草科、藜科、十字花科等植物对针茅草原的物种组成作用较大；从植物属来看，针茅属、黄耆属、蒿属、薹草属、嵩草属、棘豆属等植物对针茅草原的物种组成作用较大。青藏高原资料匮乏区针茅草原植物属的分布区类型复杂多样，其中北温带分布的属最多，达37个，包含物种82种，占一半以上，说明青藏高原针茅草原与温带植被有着密切的联系。青藏高原资料匮乏区针茅草原群落盖度平均为21.1%，地上生物量平均为60.2 g/m2，物种丰富度通常不超过13种，建群种常常在群落中占有绝对优势，建群种重要值平均为0.393。(5) 青藏高原资料匮乏区主要针茅草原类型中，紫花针茅草原不仅是资料匮乏区而且是整个青藏高原分布范围最广的针茅草原，其地上生物量和物种丰富度变异很大，其中物种丰富度最大相差22；尽管丝颖针茅草原分布范围和面积远不及紫花针茅草原，但其群落盖度(平均值34.3%)、物种丰富度(平均值17.3)和地上生物量(平均值112.3 g/m2)均居各针茅草原之首；羽柱针茅草原的建群种在群落中占据绝对优势，建群种的重要值平均为0.493，但其物种丰富度(平均值8.4)、群落盖度(平均值17.9%)和地上生物量(平均值32.4 g/m2)均处于较低水平，而且其样地物种数变化很大，样地间相差18种，这些群落特征都反映了羽柱针茅草原的集中分布区羌塘高原西北部恶劣的自然环境条件；沙生针茅草原的这些数量特征虽然均处于较低水平，但变异较小，代表了青藏高原荒漠草原的典型特征。 |
| 英文摘要 | The Tibetan Plateau is considered to be one of the most sensitive regions on the earth amid global climate change. Both vegetations and ecosystems on the plateau are relatively more vulnerable. Therefore, it is significant for focusing on the actual states and dynamics of vegetations on the Tibetan Plateau and maintaining ecological security of the region. Alpine desert is a unique vegetation type on the northwestern part of the Tibetan Plateau and the adjacent highlands, of which Ceratoides compacta alpine desert is the most typical and widespread formation. The Tibetan Plateau is also extensively covered by various Stipa communities which spread across the whole steppe region. On account of the harsh environment on the Tibetan Plateau, these assemblages have not been fully surveyed and relative researches including the formation types, distribution patterns and community characteristics have not been carried out systematically, especially in some under-explored regions such as the Changthang Plateau and the Yarlung Zangbo Valley. Based on the primary relevés collected from fieldworks in these regions (33 study sites for C. compacta alpine desert and 79 study sites for Stipa steppes) as well as the environmental data of these study sites, we studied the distribution patterns and environmental features of C. compacta alpine desert. What’s more, the categories of Stipa steppes were identified and then verified by Nonmetric Multidimensional Scaling (NMDS). We also performed Detrended Correspondence Analysis (DCA) and Detrended Canonical Correspondence Analysis (DCCA) to hunt for the distribution patterns of Stipa communities along climatic gradients. Moreover, we conducted a quantitative study on the community characteristics of the C. compacta alpine desert and 11 Stipa formations, including the species compositions and quantitative characteristics of these assemblages. The main conclusions are summarized as below:(1) The distribution of C. compacta alpine desert followed both the plateau zonality rule and the non-zonality rule of vegetation in which the latter was strongly influenced by local topography, soil moisture and chemical properties. Generally, the community was sparse with a large variance in coverage. C. compacta alpine desert was rather deficient in species and plants of some specific families including Compositae, Gramineae, Cruciferae, Leguminosae and Chenopodiaceae played an important role in the community. Moreover, 63.8% of these species belonged to the genera of north temperate areal-type. In addition, the environment of C. compacta alpine desert was mainly characterized by frost weather, climatic and physiologic drought as well as saline-alkali and barren soil. (2) Totally, Stipa steppes in under-explored regions of the Tibetan Plateau were classified into 11 formations and were verified by NMDS reasonably, among which 9 were monodominant communities (including formation (form.) Stipa subsessiliflora var. basiplumosa, form. S. purpurea, form. S. penicillata, form. S. capillacea, form. S. purpurea var. arenosa, form. S. glareosa, form. S. tianschanica var. gobica, form. S. roborowskyi, and form. S. orientalis) and 2 were polydominant communities (including form. S. purpurea + S. subsessiliflora var. basiplumosa and form. S. purpurea + S. roborowskyi). It was worth mentioning that form. S. penicillata, form. S. purpurea var. arenosa and the 2 polydominant communities were newly discovered formations. Our study also showed that Stipa steppes in under-explored regions of the Tibetan Plateau were somewhat varied in community type, but major formations were limited in number. (3) DCA showed that precipitation was the main underlying environmental gradient that influenced the variation of species and communities of Stipa steppes in under-explored regions of the Tibetan Plateau. With precipitation-related variables added, the results of DCCA revealed that precipitation especially precipitation of the wettest month (PWM) was the dominant climatic factor to determine the variations of Stipa assemblages as well as their distribution patterns. Amongst the major Stipa formations, form. S. subsessiliflora var. basiplumosa and form. S. glareosa normally distributed in arid habitats, but the rainfall for the former was of greater variance. By contrast, form. S. roborowskyi and form. S. capillacea favored moderately moist environment. Moreover, form. S. purpurea and form. S. roborowskyi could tolerate a fairly broad range of precipitation so that they were extensively spread across the Tibetan Plateau.(4) Totally, 150 species that belonged to 80 genera and 25 families occurred in the study sites of Stipa steppes in under-explored regions of the Tibetan Plateau. Plants of the families including Poaceae, Compositae, Leguminosae, Cyperaceae Chenopodiaceae, Cruciferae and plants of the genera such as Stipa, Astragalus, Artemisia, Carex, Kobresia, Oxytropis played an important part in the Stipa communities. Although the areal-types of the genera were somewhat diverse, a total of 37 genera containing 82 species were the north temperate areal-type. This indicated that Stipa steppes on the Tibetan Plateau had a close relationship with temperate vegetations. Our study also revealed that Stipa communities in these areas were fairly sparse with the mean coverage around 21.1% and above-ground biomass about 60.2 g/m2. Generally, the species richness of Stipa steppes in under-explored regions was no more than 13. Moreover, plants of the genus Stipa were of overwhelming abundance in the communities with the IV of constuctive species about 0.393.(5) Amongst the major Stipa formations, form. S. purpurea was the most widespread Stipa assemblages not only in under-explored regions but also across the whole Tibetan Plateau with a large variance in above-ground biomass and species richness (range=22). Although form. S. capillacea was far inferior in distribution, its coverage (mean=34.3%), species richness (mean=17.3) and above-ground biomass (mean=112.3 g/m2) were the maximum among them. In general, the constructive species played a supreme role in form. S. subsessiliflora var. basiplumosa with the IV around 0.493. However, the biodiversity (mean=8.4), coverage (mean=17.9%) and above-ground biomass (mean=32.4 g/m2) of the assemblage were all at low levals. Moreover, the species richness of the formation varied largely among the study sites (range=18). These quantitative characteristics all indicated that the environment in the northwest of the Changthang Plateau where form. S. subsessiliflora var. basiplumosa were mainly distributed were extremely harsh. Form. S. glareosa represented the typical desert steppes of the Tibetan Plateau with relatively low but steady levels in these attributes. |
| 中文关键词 | 青藏高原 ; 高寒荒漠 ; 垫状驼绒藜 ; 针茅草原 ; 高寒草原 ; 分布 ; 植物群落 |
| 英文关键词 | the Tibetan Plateau alpine desert Ceratoides compacta Stipa steppe alpine steppe distribution plant community |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院植物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288032 |
| 推荐引用方式 GB/T 7714 | 赵海卫. 青藏高原高寒荒漠和草原的分布格局及群落特征[D]. 中国科学院大学,2017. |
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