Knowledge Resource Center for Ecological Environment in Arid Area
| 西藏紫花针茅叶功能性状沿降水梯度的变化研究 | |
| 其他题名 | Variations in leaf functional traits of Stipa purpurea |
| 胡梦瑶 | |
| 出版年 | 2011 |
| 学位类型 | 硕士 |
| 导师 | 罗天祥 ; 张林 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 叶功能性状是植物在长期适应过程中为获得最大光合生产所形成的适应策略，比叶面积（SLA）和单位重量叶氮含量（Nmass）作为两个关键叶功能性状，分别表征了植物对光能的捕获能力和同化CO2的能力，并且二者的正相关关系几乎存在于不同的生物群落中。最新研究表明，干旱区沙地植物油蒿种群SLA和Nmass之间的关系格局沿着某一降水梯度存在一种平行位移，这是对同一物种内叶性状相互关系发生策略位移的首次报道，对于诠释环境因子对叶性状的直接影响（而不是通过影响物种更替进而影响叶性状）提供了新的证据。然而，由于沙地油蒿种群分布的独特性（沙地土壤质地差异小、其生境限于固定、半固定沙地），目前仍不清楚在不同地区其他植物种群是否也普遍存在这种策略位移现象。同时，了解植物叶性状与气候因子的关系也为揭示高海拔干旱、寒冷环境下植物对水分和温度胁迫的适应机制提供科学依据。\n本文选取广泛分布于西藏高原干旱、半干旱草地的优势物种紫花针茅（Stipa purpurea Griseb.）为研究对象，通过设置一个沿海拔（4300-4700m）差异不大的降水梯度（69-479 mm），自东至西选取当雄（草原化草甸）、纳木错（草原化草甸）、改则（荒漠草原）、珠峰（灌丛-荒漠草原）和日土（山地荒漠）5个地点，设置了44个样方/样线调查，系统测定了紫花针茅SLA、Nmass、叶密度和厚度等叶功能性状以及土壤有机质和全氮含量等因子，结果表明：\n1）跨越5个调查地区，紫花针茅SLA与Nmass总体呈现显著正相关（R2 = 0.48, P < 0.001），但分别不同降水区而言，两个性状间的正相关关系在干旱半干旱区（改则、珠峰和日土）达到显著（R2 = 0.67, P < 0.001），在半湿润区（当雄和纳木错）则不显著（R2 = 0.09, P > 0.05），未发现SLA-Nmass关系在不同降水区之间具有明显的策略位移现象。\n2）SLA、Nmass与生长季温度、降水和土壤全氮含量均没有显著关系，单位面积叶氮含量（Narea=Nmass/SLA）则随生长季平均温度增加而下降（P<0.01），但与生长季降水无显著关系。在半湿润地区，土壤全氮含量能分别解释Nmass和Narea变化的63%和48%。表明高海拔地区环境因子同时作用于SLA和Nmass，导致二者间关系在不同降水区域并没有表现出平行位移现象。\n3）作为构成SLA的两个组分，叶密度与温度呈负相关，与降水呈正相关，而叶厚度则正好相反。在半湿润区，叶厚度和叶密度分别解释SLA变化的71%和94%，其中叶密度是决定半湿润区SLA变化的主导因子；在干旱半干旱区，SLA与叶厚度呈显著负相关，但与叶密度无明显关系。表明影响SLA的两个组分（叶厚度和叶密度）在不同环境条件（尤其是水分）下发生转变。\n4）在干旱半干旱区（改则样点），发现地上生物量与对应Narea具有显著正相关关系，表明Narea的增加有助于提高植被光合生产力。\n水分是干旱、半干旱地区植物生长和生存的主要限制因子之一，单位面积叶氮含量与植物水分利用效率存在密切正相关。上述研究结果表明，在干旱半干旱区，随降水量的降低，植物通过增加叶厚度来维持不变的Narea以保持与较湿润区相似的光合生产和水分利用效率；在半湿润地区，随降水量的增加，植物叶密度增加，最终也以提高Narea的方式增加光合生产力和水分利用效率。 |
| 英文摘要 | Leaf functional traits of plants are formed in long-term adaptation to the environment to optimize photosynthetic production. Two key leaf traits, specific leaf area (SLA) and leaf mass-based nitrogen concentration (Nmass), depict the capacity of light energy capture and CO2 assimilation in plants. Both are positively correlated, which exists across wide ranges of plant populations, communities and biomes. Recent research shows that there is a strategy shift in the SLA-Nmass relationship of Artemisia ordosica, a sub-shrub species mostly distributed in sandy lands, along a rainfall gradient, which provides a new way to interpret the variations in leaf functional traits that are directly motivated by environmental factors rather than indirectly by species replacements. However, it is still unclear whether the strategy shift is universal in other widespread species populations across different habitats because Artemisia ordosica distributes specifically in fixed and semi-fixed sandy lands with a homogeneity of soil texture. Knowledge of the general relationship between leaf traits and climatic factors would help us to understand the mechanisms of plant adaptation to the water and temperature stress in high-altitude, arid and cold environments in Tibetan plateau.\nStipa purpurea is the dominant species in alpine arid- and semi-arid grasslands on the Tibetan Plateau. We conducted an east-west transect along a rainfall gradient (69-479mm) with similar altitudes (4300-4700m) in Tibet. We selected 5 locations from east to west, including Damxiong (steppe-meadow ecotone), Namco (steppe-meadow ecotone), Gatze (desert steppe), Everest (shrub steppe) and Ritu (mountain desert). 44 quadrats / line transects were set, and the variations in leaf traits of Stipa purpurea populations (SLA, Nmass, leaf density and thickness) and associated environmental factors (soil organic carbon and total nitrogen concentrations) were systematically measured. Our data indicated:\n1) There was a positive correlation (R2 = 0.48, P < 0.001) between SLA and Nmass of Stipa purpurea across the 5 locations. The positive correlation only existed in the arid and semi-arid zone (Gatze, Everest and Ritu; R2 = 0.67, P < 0.001), but not in the semi-humid zone (Damxiong and Namco; R2 = 0.09, P > 0.05). The strategy shift in the SLA- Nmass relationship was not found in Stipa purpurea.\n2) In pooled data, SLA and Nmass varied little with growing-season mean temperature (GSAT), annual precipitation (AP), and soil total nitrogen concentration (STN). Area-based nitrogen concentration (Narea=Nmass/SLA) decreased with increasing GSAT (P<0.01) but varied little with AP. In the semi-humid areas, STN explained the variations of Nmassand Narea by 63% and 48%, respectively. This indicated that SLA and Nmass of Stipa purpurea were affected by water and temperature stress at high altitudes, which explained why there was no strategy shift between SLA and Nmass along the Tibetan transect.\n3) Leaf density and thickness are two components of SLA. Leaf density was negatively correlated with GSAT and positively with AP, while leaf thickness was just the opposite. In semi-humid areas, leaf thickness and density explained the variation of SLA by 71% and 94%, respectively, in which leaf density mainly determined the variation of SLA. In arid and semi-arid areas, SLA was negatively correlated with leaf thickness but not with leaf density. \n4) Positive correlation was found between aboveground biomass and Narea in the arid and semi-arid zone (e.g. Gatze), indicating that the increase in Narea would increase plant photosynthetic productivity.\nWater stress is one of the crucial constraints on plants in arid and semi-arid areas. Higher Narea is generally correlated with higher water use efficiency of plant productivity. Our data suggest that alpine plants may maintain a constant Narea to have a similar photosynthetic productivity and water use efficiency along a rainfall gradient, which is obtained by increased leaf thickness in arid and semi-arid areas but by increased leaf density in semi-humid areas. |
| 中文关键词 | 比叶面积 ; 叶氮含量 ; 叶厚度 ; 叶密度 ; 紫花针茅 |
| 英文关键词 | specific leaf area leaf nitrogen concentration leaf thickness leaf density Stipa purpurea |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院青藏高原研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286963 |
| 推荐引用方式 GB/T 7714 | 胡梦瑶. 西藏紫花针茅叶功能性状沿降水梯度的变化研究[D]. 中国科学院大学,2011. |
| 条目包含的文件 | 条目无相关文件。 | |||||
| 个性服务 |
| 推荐该条目 |
| 保存到收藏夹 |
| 导出为Endnote文件 |
| 谷歌学术 |
| 谷歌学术中相似的文章 |
| [胡梦瑶]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [胡梦瑶]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [胡梦瑶]的文章 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
