植物适应干旱梯度变化的水分利用效率和氮磷计量机制研究

发布时间：2018-06-11 12:34

本文选题：关键词 + 叶片稳定碳同位素　；参考：《浙江大学》2013年博士论文

【摘要】：气候变化尤其是其导致的干旱胁迫对生态系统的影响及生态系统对这些胁迫因子的响应方式是当前生态学界研究的热点问题之一。由于人类活动造成的全球变暖及水资源匮乏对植物个体,群落结构乃至整个生态系统的稳定性都起到了深远的影响。所以研究长期水分亏缺对群落结构、种群分布及个体代谢造成的影响及其机理有着重要意义。本文中,我们通过分析水分利用效率、个体形态特征及化学计量比等性状研究不同植物功能群及群落特征是如何适应干旱梯度变化的。首先,我们分析了叶片稳定性碳同位素(δ13C)与植物地上密度-生物量关系(α)间的相关规律。越来越多的研究证明α不是一个恒定的值。争论依旧存在于到底是什么在改变α值中起着关键作用。通过研究叶片δ13C、植物根冠比、高茎异速比等形态特征和α值沿着东南到西北的自然干旱梯度变化的动态,我们发现α值随干旱胁迫的增大而增加,且与植物水分利用效率协变。这种协变主要是由植物根冠比、高茎异速比等形态变化驱动的,这种变化是植物在干旱胁迫下为提高水分利用效率而采用的一种适应性策略。这一信息将为理解和预测群落及生态系统过程提供理论支持。其次,我们研究了稳定碳同位素值(δ13C)在植物功能群间的变化形式及其与干旱梯度相关因子的互作方式。我们发现,由生活型划分的功能群间的δ13C在统计学上表现出显著性差异,但是在数值上的差距较小(1‰)。乔木(-26.78‰)和灌木(-26.89‰)具有相似的δ13C,均显著的高于草本(-27.49‰)。常绿灌木(-25.82‰)的δ13C显著的高于落叶灌木(-26.92‰)。多年生草本(-26.83‰)的δ13C显著的高于一年生草本(-27.10‰)。禾草类(-26.46‰)的δ13C显著的高于非禾草类(-26.96‰)。综合数据显示,δ13C显著的负相关于年平均降水量(MAP)和年平均温度(MAT),而显著的正相关于纬度和海拔。在尺度的变化上MAP存在一个阈值,如果高于这个值δ13C将不会有显著的变化。功能群间沿海拔的变化不是一致的。功能群间δ13C的变化很小只在1‰的范围内波动,而环境因子,如：MAP和MAT对δ13C的影响较剧烈(尺度上超过了4‰)。大多数功能群的δ13c响应环境变化的方式是一致的,但是它们为响应梯度变化而产生的自身变化的速率是不同的。此类信息能够帮助我们预测不同功能群应对未来环境变化而产生的分布变化。第三,我们分析了白刺(Nitraria tangutorum)叶片与根部的氮(N)、磷(P)及N：P沿干旱胁迫变化的规律。我们发现在本研究进行的区域里,四月份叶片N和P均高于全球及中国本地物种的值,而在八月又均低于这些值。白刺在四月表现出来的是N限制(平均叶片N：P=11.13),而在八月表现出来P限制(平均叶片N：P=38.78)。叶片与根部中的N和P均是高度自相关的。四月份,随着干旱胁迫的增加,叶片和根部的N和P均增加。叶片N：P沿干旱胁迫的增加而不变,根部N：P随干旱的增加而增加。我们认为叶片N：P能揭示不同生长阶段的养分供应情况,而根部N：P则能说明土壤养分是否亏缺。以上结果分别从水分利用效率和氮磷化学计量方面阐释了植物群落密度调控指数α值干旱胁迫变化的内在原因。功能群水分利用效率随干旱相关因子改变会潜在影响群落结构特征这一结果也在侧面支持了α值的变化与水分利用效率相关这一假说。个体特征及其水分利用效率和氮磷化学计量随干旱胁迫定量变化证明群落结构和功能直接或间接的被体型和功能及其相互作用所控制。
[Abstract]:The impact of climate change, especially the drought stress on ecosystems and the response of ecosystems to these stress factors is one of the hot issues in the current ecological research. The stability of plant individuals, community structures and even the entire ecosystem due to global warming and water scarcity caused by human activities will play an important role. It is of great significance to study the effect and mechanism of long-term water deficit on community structure, population distribution and individual metabolism. In this paper, we study how different plant functional groups and community characteristics are adapted to drought gradient by analyzing water use efficiency, individual morphological characteristics and stoichiometry. Change.
First, we analyzed the correlation between the carbon isotopes of leaf stability (delta 13C) and the relationship between the aboveground density and biomass (alpha). More and more studies have shown that alpha is not a constant value. The argument still exists in what is the key role in changing the alpha value. Through the study of leaf Delta 13C, plant root and crown ratio, and high speed ratio Ratio We found that the alpha value increased with the increase of drought stress and covariant with the water use efficiency of plants. This covariance is mainly driven by the morphological changes of plant root and crown ratio, high leaf speed ratio and so on. This change is the increase of plants under drought stress. An adaptive strategy for water use efficiency. This information will provide theoretical support for understanding and predicting the processes of communities and ecosystems.
Secondly, we studied the form of stable carbon isotope value (delta 13C) in plant functional groups and their interaction with drought gradient related factors. We found that the delta 13C between the functional groups divided by life type showed significant differences in statistics, but the difference in numerical values was smaller (1 per thousand). Trees (-26.78 per thousand) and shrubs (-26 .89 per 1000) has a similar Delta 13C, which is significantly higher than that of herbaceous (-27.49 per 1000). The delta 13C of evergreen shrubs (-25.82 per thousand) is significantly higher than that of deciduous shrubs (-26.92 per 1000). The delta 13C of perennial herbs (-26.83 per thousand) is significantly higher than the annual herb (-27.10 per 1000). The delta 13C of Gramineae (-26.46 per thousand) is significantly higher than that of non grasses (-26.96 per thousand). Comprehensive data show that delta 1 3C significant negative phase about annual mean precipitation (MAP) and annual mean temperature (MAT), and significant positive phase about latitude and elevation. There is a threshold for MAP on the scale change. If higher than this value [delta] 13C, there will not be a significant change. The variation between the functional groups along the elevation is not consistent. The change of delta 13C between functional groups is only 1 per thousand. Range fluctuations, while environmental factors such as MAP and MAT have a severe impact on Delta 13C (over 4 per thousand on the scale). The delta 13C of most functional groups is consistent in response to environmental changes, but their rate of change in response to gradient changes is different. This kind of information can help us predict different functional groups. The changes in the distribution of the future environment.
Third, we analyzed the changes of nitrogen (N), phosphorus (P) and N:P in the leaves and roots of white thorn (Nitraria tangutorum). We found that in the region of this study, the leaves N and P in April were higher than those of the global and Chinese native species, but in August they were all lower than those in April. In April, white thorn showed N limitation. (average leaf N:P=11.13), and in August, the P restriction (average leaf N:P=38.78) was shown. The N and P in the leaves and roots were highly autocorrelation. In April, with the increase of drought stress, the N and P in the leaves and roots increased. The leaf N:P did not change along the drought stress, and the root N:P increased with the increase of drought. We recognized that the root N:P increased with the drought. Leaf N:P can reveal nutrient supply at different growth stages, while root N:P can explain whether soil nutrient is deficient.
The above results explain the internal causes of drought stress change from the water use efficiency and the chemical measurement of nitrogen and phosphorus respectively. The result of the change of water use efficiency with drought related factors will potentially affect the structure characteristics of the community. The result also supports the change of alpha value and the water use efficiency in the side. The individual characteristics, their water use efficiency and the quantitative changes of nitrogen and phosphorus stoichiometry with drought stress prove that the structure and function of the community are directly or indirectly controlled by the body shape and function and their interaction.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：Q945

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