Knowledge Resource Center for Ecological Environment in Arid Area
| 水分梯度下黑河流域荒漠植物群落结构及化学计量特征研究 | |
| 其他题名 | Plant community structure and ecological stoichiometry of desert ecosystem in the Heihe basin along moisture gradients |
| 张晓龙 | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 郑元润 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 干旱区内陆河流域生态环境极其脆弱，荒漠植被在保护区域生物多样性和维持生态系统稳定方面至关重要。水分条件是荒漠地区植物生长和分布的主要限制因子，其空间分布及变化影响植物的种类和数量，控制植被分布格局、多样性特征，以及荒漠生态系统的结构和功能。生态化学计量学为分析植物的养分利用状况提供了一种重要手段。在水分梯度下开展荒漠植物群落特征及化学计量特征研究，有助于揭示区域植被组成、物种多样性、养分利用特征及其对环境的适应机制，对干旱区内陆河流域荒漠植物资源管理和恢复、脆弱生态系统保护具有重要意义。本文通过大量野外荒漠植物群落调查和土壤样品分析，研究了黑河流域水分梯度下荒漠植物群落特征及其影响因素，并对群落优势种化学计量特征及其与环境因子的关系进行了研究。取得如下主要结果：（1）黑河流域中下游荒漠和下游荒漠河岸林植物群落结构简单，物种组成单一，单寡种优势群落现象极为明显。荒漠植物群落随水分条件不同而不同，在中、下游荒漠区域降水梯度下，随降水减少依次为尖叶盐爪爪（Kalidium cuspidatum (Ung. Sternb.) Grub.）群落、珍珠猪毛菜（Salsola passerina Bunge）群落、细枝盐爪爪（Kalidium gracile Fenzl）群落、沙蒿（Artemisia desertorum Spreng.）群落、毛瓣白刺（Nitraria praevisa Bobr.）群落、西伯利亚白刺（Nitraria sibirica Pall.）群落和梭梭（Haloxylon ammodendron (C. A. Mey.) Bunge）群落。在下游荒漠河岸林中，主要为以胡杨（Populus euphratica Oliv.）、多枝柽柳（Tamarix ramosissima Lebed.）等为优势种的植物群落。物种多样性指数偏低，Shannon-Wiener指数、Simpson指数、Margalef指数和Pielou指数最大值仅为1.14、0.59、0.99和0.75。水分条件与该区群落组成的关系十分密切，在区域降水梯度下，植物群落的物种多样性随降水量增加大体呈先上升后下降趋势；在地下水埋深梯度下，植物群落的物种多样性随地下水埋深增加大体呈双峰型变化趋势。（2）在中、下游荒漠区域降水梯度下，随降水增加，物种丰富度、地上生物量、群落盖度、叶片投影盖度和叶面积指数均呈显著上升趋势，而群落高度随降水增加显著下降。降水是影响土壤属性的重要因素，随降水增加，土壤含水量（0-10 cm）、土壤含水量（10-30 cm）、土壤总氮和土壤总碳呈显著上升趋势，土壤有效钾呈显著下降趋势。土壤容重和土壤pH受母质影响明显。植物群落特征主要受降水影响，降水和土壤可解释群落特征变化的76.9%，降水对群落特征变化的解释率大于土壤以及降水和土壤的交互作用的解释率。（3）在中、下游荒漠区域降水梯度下，群落主要优势种叶片C、N、P、K平均含量分别为301.22 mg g-1、18.81 mg g-1、1.74 mg g-1和17.59 mg g-1；C:N、C:P和 N:P分别为15.88、199.68和12.27。与全球尺度、全国尺度以及其它干旱区区域尺度相比，黑河流域荒漠植物具有较低的叶片C含量和叶片N:P值，相对稳定的叶片N含量和叶片P含量，植物生长倾向于受N元素控制。降水对叶片化学计量分布特征影响不显著，在所有解释变量中，土壤含水量（30-50 cm）是影响植物叶片化学计量特征最主要的因子。（4）在荒漠河岸林地下水埋深梯度下，植物群落结构和分布主要受地下水埋深的影响。随地下水埋深增加，物种丰富度、地上生物量、群落高度、群落盖度、叶片投影盖度和叶面积指数均呈显著下降趋势。土壤含水量（0-30 cm）、土壤含水量（30-50 cm）、土壤总氮、土壤总碳、土壤有效磷和土壤有效钾随地下水埋深的增加呈显著下降趋势，土壤容重和土壤碳氮比随地下水埋深增加呈显著上升趋势，土壤pH和土壤电导率与地下水埋深呈显著二次曲线关系。地下水埋深和土壤属性共同影响荒漠河岸植物群落特征，地下水埋深、土壤容重和土壤pH解释群落变化的85.8%，其中地下水埋深在解释率中所占比例最大（58.2%），其后依次是地下水埋深和土壤容重交互作用（27.9%），地下水和土壤pH交互作用（1.6%），而土壤容重和土壤pH单独解释率相对较低。（5）在荒漠河岸林地下水埋深梯度下，群落主要优势种叶片C、N、P、K平均含量分别为327.29 mg g-1、13.88 mg g-1、0.58 mg g-1和6.71 mg g-1；C:N、C:P和 N:P分别为24.41、614.94和26.12。与全球尺度、全国尺度以及其它干旱区区域尺度相比，荒漠河岸林优势种具有较低的叶片C含量、叶片N含量、叶片P含量和叶片K含量，较高的叶片C:N，C:P以及N:P。地下水对叶片化学计量特征影响显著，地下水埋深和pH可很好解释叶片化学计量特征的差异。 |
| 英文摘要 | Environment in arid inland river basin is extremely frail, desert vegetation played a crucial role in protecting biodiversity and maintaining ecosystem stability. Water in desert regions acts as the key limiting environmental factor in vegetation growth and distribution. The spatial distribution and variability of water limit the kinds and numbers of desert plants, and control the distribution and diversity of vegetation, and determine the structure and function of desert ecosystem. Ecological stoichiometry could provide an integrative approach for analyzing plant nutrient utilization. The studies on community characteristics and leaf stoichiometric traits under different moisture gradients could help to reveal the distribution and composition of vegetation, biodiversity, characteristics of plant nutrition utilization and adaptation mechanism to the climate change, therefore, it is important for desert vegetation management and restoration.Based on a large number of desert plant community investigations and soil samples collections in the field, the dissertation studied the structure and distribution of desert plant community, leaf stoichiometric traits of dominant species and their influencing factors under different moisture gradients in Heihe river basin. The main results are as follows:(1) In desert regions in the middle and lower reaches of Heihe river and desert riparian forest in lower reaches of Heihe river, the structure of communities were simple and the scarcity of plant species, monotypic (oligotypic) community types were obvious. The desert plant communities changed along different moisture gradients. Under the gradients of regional precipitation, with decreasing precipitation gradients, the communities were dominated by Kalidium cuspidatum, Salsola passerina, Kalidium gracile, Artemisia desertorum, Nitraria praevisa, Nitraria sibirica and Haloxylon ammodendron. In desert riparian regions in lower reaches, the communities were dominated by Populus euphratica and Tamarix ramosissima etc.. The species diversity indices of desert plant communities were low, the maximum Shannon-Wiener, Simpson, Margalef and Pielou values were 1.14, 0.59, 0.99, 0.75, respectively. The water condition is closely related to the community composition. Along the precipitation gradient, the species diversity of plant communities showed a first increased and then decreased trend. Additionally, along the groundwater depth gradient, the species diversity of plant communities formed a bimodal pattern. (2) Under the gradients of regional precipitation in the middle and lower reaches, with increasing precipitation, species richness, aboveground biomass, community coverage, foliage projective cover (FPC), and leaf area index (LAI) significantly increased, while community height decreased. Precipitation was an important factor that affected soil properties, soil water content at 0-10 cm, soil water content at 10-30 cm, soil total nitrogen and soil total carbon showed a significant decreased trend with increasing precipitation. Soil bulk density and soil pH were affected by soil parent material. Precipitation was the main drivers of desert plant community, precipitation and soil properties jointly explained 76.9% of the vegetation variance, precipitation was more important in explaining vegetation variance than soil properties and the interaction of precipitation and soil properties. (3) Under the gradients of regional precipitation in the middle and lower reaches, for dominant plant species, the average values of leaf C, N, P, K, C:N, C:P, N:P were 301.22 mg g-1, 18.81 mg g-1, 1.74 mg g-1, 17.59 mg g-1, 15.88, 199.68, 12.27, respectively. Compared to global scale, national scale and other arid regions, The desert plants were characterized by lower leaf carbon (C) and nitrogen:phosphorus (N:P) levels, and stable N and P, and these parameters did not change significantly with precipitation. In all the explanation variables, soil water content (30-50 cm), rather than precipitation, was the main driving factor of desert plant leaf stoichiometric traits.(4) Under the gradients of groundwater depth in desert riparian forest in lower reaches, desert plant community structure and distribution were affected by groundwater depth, and community characteristics showed a significant trend with increasing groundwater depth. Species richness, aboveground biomass, community coverage, community height, foliage projective cover (FPC) and leaf area index (LAI) significantly decreased with increased groundwater depth. With increasing groundwater depth, soil water content, soil total nitrogen, soil total carbon, soil available phosphorus and soil available potassium decreased, while the soil bulk density and soil carbon:nitrogen (C:N) ratio increased. Soil pH and soil electrical conductivity followed quadratic function relationships with groundwater depth. Groundwater depth and soil were associated with vegetation variance, explaining 85.8% of the vegetation variance. Groundwater depth had the largest contribution (58.2%), followed by the interaction of groundwater depth and soil bulk density (27.9%), and then the interaction of groundwater depth and soil pH (1.6%), soil bulk density and soil pH had a relatively small contribution. (5) Under the gradients of groundwater depth in desert riparian forest in lower reaches, the average values of leaf C, N, P, K, C:N, C:P, N:P were 327.29 mg g-1, 13.88 mg g-1, 0.58 mg g-1, 6.71 mg g-1, 24.41, 614.94, 26.12, respectively. Compared to global scale, national scale and other arid regions, The riparian desert plants were characterized by lower leaf carbon (C), nitrogen (N), phosphorus (P), potassium (K), and higher carbon:nitrogen (C:N), carbon:phosphorus (C:P), nitrogen:phosphorus (N:P). Leaf stoichiometric traits was affected significantly by groundwater depth, groundwater depth and soil pH jointly well explained the variance of leaf stoichiometric traits. |
| 中文关键词 | 荒漠植被 ; 化学计量学 ; 黑河流域 ; 水分梯度 ; 土壤属性 |
| 英文关键词 | Desert Vegetation Ecological Stoichiometry Heihe River Basin Moisture Gradients Soil Properties |
| 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/2XILL650/288208 |
| 推荐引用方式 GB/T 7714 | 张晓龙. 水分梯度下黑河流域荒漠植物群落结构及化学计量特征研究[D]. 中国科学院大学,2018. |
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