Knowledge Resource Center for Ecological Environment in Arid Area
| 退化小针茅草原植物群落对水热变化的适应机理研究 | |
| 其他题名 | Adaptation mechanisms of plant community to changing temperature and precipitation in a degraded Stipa klemenzii steppe |
| 侯彦会 | |
| 出版年 | 2014 |
| 学位类型 | 博士 |
| 导师 | 张新时 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 气候变暖和降水变化影响植物生长发育、适应策略和生产性能，导致植物功能性状发生变化，进而改变种间关系，最终影响群落的结构、组成和功能。位于干旱半干旱区的内蒙古荒漠草原在维持生物多样性和生态系统稳定性及保护人类生存环境方面起着至关重要的作用。然而，目前关于荒漠草原植物群落对气候变化的响应及其内在机制仍然缺乏认识。 本研究以对气候变化较为敏感的退化小针茅草原生态系统为研究对象，采用红外辐射器增温模拟气候变暖、人工灌溉模拟降水量增加等控制实验手段，从不同层次(物种、功能群、群落)探讨内蒙古退化小针茅草原植物群落对气候变暖与降水变化的响应及其内在机理。主要结果如下： (1) 红外增温对空气和土壤的影响存在不对称性。红外增温对空气的增温效果(+0.22℃)小于对土壤的增温效果(+2.78℃)，增温对空气温度和湿度的影响均未达到显著性水平，而增温显著提高了土壤温度，降低了土壤湿度。红外增温对夜间土壤温湿度的影响大于白天，而且在凌晨时红外增温对土壤温度的增温效果最好，在午后的增温效果最差。红外增温对空气和土壤日最高温度的增温效果均弱于对日最低温度的增温效果，降低了气温和土温日较差。 (2) 8个植物功能性状在不同物种间的差异性及其与水热因子的关系表明，我国退化小针茅草原植物功能性状存在巨大物种差异。不同物种具有各自不同的资源利用策略，能对水热变化作出不同的响应和适应对策。一年生蒿属植物栉叶蒿和茵陈蒿具有更高的植株高度、更大的比叶面积，小针茅叶片具有更高的氮素含量和干物质含量，而糙隐子草叶片则具有更高的δ13C值，即具有更高的水分利用效率。这些功能性状的差异使得蒿属植物和C4植物具有较强的竞争力，而小针茅植物的资源利用效率较为保守，但抗旱能力较强。增温和增加降水均显著影响植物的功能性状，降水变化解释了荒漠草原大多数植物功能性状的变化，温度和降水对植物功能性状的交互影响不显著。植物功能性状与土壤温湿度具有一定的相关性。植株高度和叶面积两个功能指标能很好地解释植物个体生物量的变化。 (3) 增温降低了物种丰富度，而增加降水提高了物种丰富度，且两者对物种丰富度的影响是非交互性的。短期的增温和增水试验没有明显改变退化荒漠草原植物群落结构，但却使植物群落物种组成发生了改变。增水对物种、功能群和群落的影响比增温的影响更显著。总体而言，土壤水分是影响退化小针茅群落物种和功能群相对盖度及物种丰富度的主要因素。不同水热条件下，植物个体种和功能群的盖度明显不同。降水的增加促进了多年生C4植物糙隐子草的生长和在群落中的占比，但却降低了栉叶蒿和茵陈蒿在群落中所占的比例，增温在增加C4禾草占比的同时降低了C3半灌木的占比；而且增温和增水对植物群落组成的交互影响不显著。 (4) 退化小针茅草原物种、功能群和群落地上生物量具有显著的年际差异，湿冷的2012年群落地上生物量高于湿热的2011年。群落地下生物量的年际变化较小。植物群落地下与地上生物量比值也较为稳定，年际间变化不显著，增水处理对其也无显著影响，但增温使地下与地上生物量比值显著增加了32.46%。优势物种栉叶蒿和茵陈蒿地上生物量年际波动大，致使功能群和群落的地上生物量也呈现较大的年际变异。增温对不同物种、功能群和群落生物产量的影响较小，而增水所产生的效应比增温更加显著，土壤水分是影响退化小针茅草原物种、功能群和群落生物量的主要因素。增温和增加降水对植物群落生产力的影响更多地表现为可加性而非交互性。 |
| 英文摘要 | Climatic warming and precipitation changing affect the growth and development, adaptive strategies, and performance of individual plant species, resulting in shifts of plant functional traits and interactive relationships among plant species, and ultimately influencing community structure and composition as well as function. Desert steppe of Inner Mongolia located in the arid and semiarid region plays a vital role in maintaining the biodiversity and the stability of ecosystem and protecting natural environment. However, the adaptation mechanisms of desert steppe to climate change are still elusive. In this study, we chose the degraded Stipa klemenzii steppe ecosystem which is relatively sensitive to climate change as the research object, and conducted a field experiment with climatic warming manipulated by infrared heaters and increasing precipitation simulated by watering, to investigate the interactive effects of climatic warming and precipitation change on plant community and to explain the adaptation mechanisms of desert steppe to climate change from species, functional groups, and community level. The key findings are as follows: (1) Infrared warming effects on air and soil were asymmetric. Infrared warming effect on air (+0.22 ℃) was less than that on soil (+2.78 ℃), the warming effects on air temperature and air humidity were insignificant, while warming significantly increased soil temperature and decreased soil moisture. Infrared warming effects on soil temperature and soil humidity during the nighttime were greater than those during the daytime. Maximum increment in soil temperature caused by infrared heaters appeared in the morning while the minimum increment appeared in the afternoon. Infrared warming had greater warming effects on daily minimum air and soil temperatures than those on daily maximum air soil temperatures, resulting in reductions in diurnal air-temperature range and diurnal soil-temperature. (2) Eight plant functional traits in different plant species and their relationships with warming and increased precipitation indicated that there were huge differences in plant functional traits among four dominant species in degraded Stipa klemenzii steppe. Different plant species had different resource utilization strategies, and they could make different responses and adaptation strategies to hydrothermal changes. Warming and increased precipitation significantly affected plant functional traits, but there were significant differences among plant species. Annual artemisia plants - Neopallasia pectinata and Artemisia capillaries had greater plant height, bigger specific leaf area, while Stipa klemenzii had higher leaf nitrogen content and leaf dry matter content, and Cleistogenes squarrosa had higher leaf δ13C value, that is to say, it had higher water use efficiency. The Artemisia plants and C4 plants had higher competitiveness, and Stipa klemenzii had more conservative resource utilization efficiency, and higher drought resistance ability. Both warming and increased precipitation significantly affect plant functional traits, and precipitation change explained the most variations of plant functional traits. The interaction between warming and precipitation on plant functional traits was insignificant. Plant functional traits were significant relevant with soil temperature and soil humidity. Individual plant biomass variations could be explained by plant height and leaf area. (3) Increased precipitation promoted plant species richness while warming significantly decreased species richness, and their effects were more additive rather than interactive effect. Although short-term treatments did not significantly change plant community structure in degraded desert grassland, plant community composition in the desert steppe was altered under simulated climatic changes. The effects of increasing precipitation influenced plant species-, functional group-, and community-level responses more than the effe |
| 中文关键词 | 适应机理 ; 退化小针茅草原 ; 气候变暖 ; 降水变化 |
| 英文关键词 | adaptation mechanisms climatic warming degraded Stipa klemenzii steppe precipitation change |
| 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/2XILL650/287456 |
| 推荐引用方式 GB/T 7714 | 侯彦会. 退化小针茅草原植物群落对水热变化的适应机理研究[D]. 中国科学院大学,2014. |
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