Knowledge Resource Center for Ecological Environment in Arid Area
| 树木生长与生理生态特征对温度和干旱胁迫的响应 | |
| 其他题名 | Growth and ecophysiological characteristics of trees response to temperature and drought stress |
| 王晓雨 | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 高霄鹏 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 气候变化引起的气候变暖和降水格局变化深刻影响陆地森林生态系统的结构、功能和稳定性。这种影响是动态的，并具有多面性和不确定性。比如以往受低温限制的部分寒区森林，因为气候变暖而出现阶段性的增长，而受水分限制的部分旱区森林，在变暖以及极端天气的影响下大幅缩减。区域以及全球尺度上森林面积的变化取决于这些持续发生的增长（森林扩展）和减少（森林缩减）的净结果。当前，尽管有研究报道了部分寒区森林的扩张趋势，以及干旱导致了全球性的大面积树木死亡事件增加，但是有关气候变化对树木生长、生存的影响机理研究仍存在许多争议和不确定性，因而，仍然是各国学者广泛关注的热点问题。本研究分别以典型寒区森林分布区高山林线上的建群种—岳桦（Betula ermanii Cham.）和旱区优势种—柔毛栎（Quercus pubescens Willd.）为研究对象，通过野外调查、长期定点监测和控制实验等方法，探讨了气温升高和干旱对树木生长以及生理适应性特征的影响，旨在揭示气候变化对两大敏感区域树木影响的机理。研究结果可以为区域尺度上的森林适应气候变化的敏感性及风险评估提供依据，也可以帮助更好地预测未来气候变化情景下的森林动态。主要研究结果：（1）气候变化导致了林线岳桦不同大小个体胸径（DBH）-树高（H）生长关系的分化。变暖使岳桦幼树（H < 140 cm）径向生长速率的增幅大于高生长，幼树变得更为矮曲；大树（H ≥ 140 cm）则正好相反，树形变得更为尖削。在长白山北坡海拔1700 ~ 1900 m，岳桦树形逐渐变得尖削，而在1900 ~ 2050 m范围内，树形逐渐矮曲。另外，与同海拔的其他几个树种相比，岳桦树形可塑性更高。（2）长白山北坡连续林线与近百米以上呈斑块状中生长的岳桦，具有相似的生境条件和生理生态特征。这表明，微地形是高山植物生长与生存的重要避难场所，首先占据有利的微地形（如略凹陷的水道）可能成为高山植被向高海拔扩展分布的重要方式。总体上，寒区树木以不同生长形式（如树形变化）响应气候变化，但受限于森林边缘土壤、地形等微环境，其总体响应缓慢。（3）干旱和氮添加未对于树木早春展叶产生显著影响，但两者均与个体在早春展叶后期的霜冻伤害有显著关联。短期干旱使叶生物量显著降低，增加根在整株生物量中的分配比例；长期干旱限制所有组织的生物量累积。处理期间，氮添加未对组织生物量及其分配造成影响。极端干旱时，氮添加有利于干旱胁迫后个体功能的恢复和生长。（4）短期干旱对栎树各组织NSC浓度（C储存）无显著影响，但持续干旱使各组织NSC浓度显著降低。极端干旱下栎树根中淀粉的阈值在10%左右。植物适应或应对干旱胁迫时，K离子担负重要功能如维持碳水化合物由源到汇的运输。总体上，对于旱区森林而言，树木个体生长、生存对变暖和干旱的响应迅速，而氮沉降又在很多方面加剧了不利影响。加之极端气候以及干扰因素的发生，旱区森林缩减程度将进一步加剧。 |
| 英文摘要 | Climate change in the main forms of climate warming and precipitation pattern change have profound impact on the structure, function and stability of terrestrial forest ecosystems. This influence is dynamic, multifaceted and uncertain. Most forests in the cold regions were previously restricted by cold climate, but due to climate warm, some of those forests experienced periodic increase. On the opposite, some water-restricted forests in the arid areas have been greatly reduced under the influence of both warming and extreme weather. Changes in the forests cover at the regional and global scales depend on the net result of these sustained growth (forests expansion) and reduction (forests reduction) dynamics. At present, a large amount of studies have reported that warm climate has caused the forest to move upslope or northward, and droughts induced trees mortality events occurred more often than before. But still, there are many controversies regarding the mechanism of the impact of climate change on the growth and survival of trees, so there is still a need to gain insight to this knowledge. In this study, Betula ermanii Cham., a dominant species on the alpine treeline, and Quercus pubescens Willd., a dominat species in arid regions were selected for the study. Field investigation, long-term fixed monitoring site, and control experiment were conducted to understand how warm climate and drought affects growth and physiological adaptability of trees. This study aimed to reveal the mechanism of climate change impact on trees in these two sensitive regions, and to provide basis for better predicting the dynamics of forests in the context of future climate change. Got the following results: (1) Climate change has led to the growth differentiation of tree height (H) – tree diameter (DBH or BD) relationships of treeline trees. The warm climate increased more the radial growth rate of young trees (H < 140 cm) in comparison to the height growth, thus the young trees became more dwarfed. The large trees (H ≥ 140 cm) had the opposite response that tree form become to be more sharp. At the elevation from 1700 to 1900 m a.s.l., the birch tree form gradually tapers, and gradually dwarfs at the elevation from 1900 to 2050 m a.s.l. In addition, compared with several other species at the same altitude, birch showed higher plasticity in the tree forms. (2) The birch trees grown in the patchs on the transition ecotone had similar microenvironmental conditions and physiological performances. That means microtopography is an imorportant reguge for the growth and survival of alpine plants. Through occupying advantages microsites (such as the slightly concave waterways), alpine trees can distribute to higher altitudes. In general, trees in the cold regions respond to climate changes in different ways (such as changes in tree form), but limited by the surrounding microenvironments such as soils, topography, their overall response is slow.(3) In early spring, water stress and nitrogen addition show no significant effect on leaf development of oak, but both factors were significantly associated with frost damage of oaks in the late spring. Short-term drought significantly reduced leaf biomass, while increased the proportion of biomass allocation in root. Long-term drought limited biomass accumulation across all the organs, but during the whole study period, nitrogen had no effect on biomass of all the organs. For the extreme water stressed trees, nitrogen addition facilitates their after drought revovery and growth rate.(4) The short-term drought had no significant effect on NSC concentrations (C storage) in the organs of oaks, but the long-term drought resulted in a significant decrease in NSC concentrations in all the organs. The threshold of starch in roots under extreme drought is around 10%. When plants adapt to or respond to drought stress, K+ may plays an important role in maintaining carbohydrate transport from source to sink. So, for dryland forests, individual tree growth and survival response quickly to warming and drought, and nitrogen deposition intensifies adverse effets in many ways. Coupled with the occurrence of extreme weather and disturbance factors, the extent of forest shrinkage will further increase. |
| 中文关键词 | 低温胁迫 ; 干旱 ; 碳储存 ; 非结构性碳水化合物（NSC） |
| 英文关键词 | Cold stress Drought Carbon storage Non-structural carbohydrate (NSC) |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院沈阳应用生态研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288111 |
| 推荐引用方式 GB/T 7714 | 王晓雨. 树木生长与生理生态特征对温度和干旱胁迫的响应[D]. 中国科学院大学,2018. |
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