KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 古尔班通古特沙漠南缘不同生活型植物昼夜气孔导度和蒸腾特征 | |
| Alternative Title | The characteristics of stomatal conductance and transpiration of different plants in southern fringe of the Gurbantonggut Desert,China |
| 孟德坤 | |
| Subtype | 硕士 |
| Thesis Advisor | 马剑英 |
| 2020-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 理学硕士 |
| Keyword | 气孔导度 蒸腾速率 昼夜节律 水分利用效率 荒漠区 stomatal conductance transpiration rate circadian rhythm water use efficiency desert |
| Abstract | 植物叶片通过气孔与外界环境进行物质交换，在水分损失和光合碳固定之间进行权衡。 对于所有陆地植物来说，光合作用固定 CO2 不可避免会导致蒸腾水分散失。 一直以来， 植物水分利用模型预测植物在夜间无碳吸收时会关闭气孔。荒漠植物的生长和生存主要受水力条件的影响，许多植物（除 CAM 植物）在黄昏和夜间气孔闭合不完全，不仅不能固定碳，而且损失一定量的水分， 了解荒漠地区植物昼夜气孔行为和调控机制可以更加深入地分析荒漠植物夜间气孔开放的作用。 研究荒漠植物夜晚蒸腾与环境因子的关系，明确植物与大气的水分运输过程，对预测气候变化背景下植物与大气之间的碳循环和水循环具有重要意义。本研究通过测定古尔班通古特沙漠南缘不同生活型植物的气体交换参数、 稳定性碳同位素组成和土壤生态化学计量特征等指标， 研究昼夜条件下不同生活型植物的气体交换特征及水分利用效率， 揭示不同生活型植物的水分利用能力和昼夜气孔调节机制。结果表明：（1） 荒漠植物均存在夜晚气孔打开和夜间蒸腾失水现象。所有植物在雨后的夜晚气孔导度均大于雨前的气孔导度， 水分条件是荒漠植物表达其夜间气孔打开作用潜力的关键控制因子。部分植物可能存在水分胁迫，但依旧保持一定的夜晚气孔导度和蒸腾作用，在水分充足的条件下， 夜晚气孔导度和蒸腾失水量增大。（2） 不同植物的气孔导度和蒸腾速率日变化过程相似，上午时段随光强增强而增大，而下午时段受温度和水分限制的影响，气孔导度和蒸腾速率有减小趋势。 尽管植物的气孔导度和蒸腾速率在夜晚有缓慢增大的趋势，但并未如昼夜节律假说提到的那样在黎明时段达到最大值，根据植物夜晚气孔导度与白天气孔导度比值的结果，只有灌木昼夜气孔导度的差异最小，与假说预期的结果相符。（3） 尽管植物在白天和夜晚都可以调控气孔，但白天和夜晚气孔控制机制存在差异。环境变量中大气 CO2 浓度、土壤水分、温度和湿度等都对昼夜气孔调控具有重要的影响。驱动植物昼夜蒸腾失水的因素不止环境变量， 植物昼夜气孔导度除受环境因子影响外，可能还与植物自身特性有关。（4）水分匮乏是荒漠区最主要的环境特征， 高效利用水分事关植物生存和繁衍。研究区代表性 C4 植物的夜晚气孔导度与其长期水分利用效率呈正相关关系， 尽管夜间由气孔打开引起的蒸腾失水增加了植物的水分损耗，但夜晚蒸腾抑制了植物水力再分配， 黎明前的气孔启动可以促进植物在清晨时段增大气孔导度，加速了碳同化速率，从而了提高白天（尤其是清晨） 植物光合水分利用效率。研究区代表性 C3 和 C4植物中存在显著的夜间气孔导度和蒸腾作用， 这些观察结果与最适气孔理论并不一致。植物气孔对陆地生态系统的碳通量和水通量有很强的影响，而夜间气孔行为将导致估计植物水分利用效率和生态系统碳水循环方面存在较大偏差。 研究结果对于预测全球变化背景下陆地大气相互作用和碳循环是至关重要的。 |
| Other Abstract | For all land plants, photosynthetic fixation of CO2 inevitably leads to the loss oftranspiration water. Stomata serve as a pathway for plant leaves to exchange materialwith the environment and make a trade-off between water loss and carbon fixation.Plant water use models predict that plants will close stomata when they have nocarbon uptake at night. The growth and survival of plants in arid regions are mainlyrestricted by water. Stomata of many plants (except CAM plants) close incompletelyat dusk and night, which not only fails to fix carbon, but also loses a lot of water.Therefore, studying the day and night stomatal behavior and regulation mechanism ofplants in desert will shed light on the role of desert plants at night. Further exploringthe relationship between desert plant day and night transpiration and environmentalfactors can improve the understand of the process of water and heat transfer betweendesert plants and the atmosphere, which is of great significance for predicting thecarbon cycle and water cycle between plants and the atmosphere under thebackground of climate change.This study by measuring the Gurbantonggut Desert south margin, different lifeforms of gas exchange parameters, stable carbon isotopic composition and soilecological characteristics of stoichiometric indicators, such as day and night studyunder the condition of different gas exchange characteristics of plant life-form andwater use efficiency, and reveal different day and night life of plant water use abilityand stomatal regulation mechanism. The results show that:(1) At night, stomata opening and transpiration loss were found in desert plants.Stomatal conductance of all plants at night after rain was higher than that before rain,and water condition was the key controlling factor for desert plants to express theirstomatal opening potential at night. Some plants may have water stress, but stillmaintain a certain stomatal conductance and transpiration at night, under the condition of sufficient water, stomatal conductance and transpiration loss at night increased.(2) Similar to the diurnal variation process of stomatal conductance andtranspiration rate of plants, stomatal conductance and transpiration rate increased withthe increase of light intensity in the morning, but decreased with the influence oftemperature and water restriction in the afternoon. Although plant stomatalconductance and transpiration rate has the tendency of increase with the slow at night,but not such as circadian rhythm hypothesis mentioned peaked at dawn time,according to plant stomatal conductance at night and the result of stomatalconductance ratio during the day, day and night only shrubs stomatal conductanceminimize differences, consistent with the hypothesis the expected result.(3) Although the stomata of plants can be regulated in both day and night, thestomatal control mechanism is different in day and night. Atmospheric CO2concentration, soil moisture, temperature and humidity all have important effects onstomatal regulation. Environmental variables are not the only factors that drive waterloss during diurnal transpiration of plants.(4) Water scarcity is the most important environmental feature of desert areas,and efficient water use is related to plant survival and reproduction. Representative C4plants in the study area the night of the stomatal conductance and water use efficiencywas positively related to relationship, although the transpiration of water loss causedby stomatal opening night increased plant moisture loss, but the night transpirationinhibits plant hydraulic redistribution and predawn stomatal priming could lead tohigh stomatal conductance early on the subsequent morning, thus improving thedaytime (especially in the early morning) plant photosynthetic water use efficiency.Significant nocturnal stomatal conductance and transpiration were observed inrepresentative C3 and C4 plants in the study area, and these observations wereinconsistent with optimal stomata theories. Stomata has a strong influence on thecarbon and water fluxes of terrestrial ecosystems, and stomatal behavior at night willlead to a large deviation in the estimation of plant water use efficiency and ecosystem carbon and water cycle. This is crucial for predicting the terrestrial atmosphereinteractions and carbon cycles in the context of global change. |
| Subject Area | 生态学 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15438 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 孟德坤. 古尔班通古特沙漠南缘不同生活型植物昼夜气孔导度和蒸腾特征[D]. 北京. 中国科学院大学,2020. |
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