城市典型植物冠层异质性对叶片和冠层 碳收支的影响
文献类型：学位论文
| 作者 | 王晓琳 |
| 学位类别 | 博士 |
| 答辩日期 | 2016-06 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 胡聃 |
| 关键词 | 冠层异质性，叶片碳收支，冠层碳收支，尺度转换，城市 crown heterogeneity, crown carbon budget, leaf carbon budget, scale up, urban |
| 其他题名 | Dynamic spatial patterns of crown affect carbon budget of leaf traits and canopy in typical urban plant |
| 学位专业 | 生态学 |
| 中文摘要 | 植被冠层部分的碳收支占整个植株的大部分，冠层碳收支的估算对初级净生产力的估计具有重要作用。目前普遍认可、使用最多的估算方法是用单叶生理生态指标外推到冠层的方法，因此估算的核心问题是叶片指标的尺度放大问题。树木和作物冠层的时间和空间异质性对尺度放大提出很大挑战。目前，尺度放大方法模型极少考虑冠层内部生态因子时、空异质性互作问题以及冠层叶片功能的动态适应过程，造成了冠层叶片碳收支空间变异的研究结论不一致。为此，本研究选取典型植物研究了冠层水平生态因子时空变异特征及冠层叶片结构和功能指标的空间异质性特征，并充分利用冠层异质性，使用冠层生态分区（CEZ）方法研究了冠层水平上叶片形态和功能对环境的响应过程及主导因素，估算了冠层昼夜碳收支总量。典型植物冠层生态因子昼夜时空变异研究结果表明：1）冠层水平生态因子具有明显的昼夜时间变化，并受天气条件影响；2）冠层水平光辐射强度和气温的昼夜动态具有明显的空间垂直变异，但空间变异在特定的时间、特定的冠层位置表现出来，不同天气条件下空间异质性特征也不同；3）冠层内部空气湿度和大气CO2浓度无明显的垂直变化。基于此，本研究定量描述了冠层异质性，即对冠层生态因子空间变异进行了生态分区：晴天四区模式，阴天另一种四区模式。 CEZ提供了一个系统的田间开放条件下冠层研究体系，即在一个CEZ内部冠层水平生态因子在统计上是相对稳定的，无空间异质性；在CEZ之间存在显著差异的生态因子梯度，可以作为冠层水平叶片环境响应研究的梯度。基于CEZ分区，我们研究了冠层水平叶片碳收支的空间分布和昼夜动态特征，并分析了叶片碳收支影响因子的相对贡献率及其冠层空间差异。结果表明：1）生态因子对碳收支指标昼夜变化有显著的独立贡献率；气温在晴天条件下对碳收支指标昼夜变化贡献率最大，而光强对阴天条件下碳收支指标昼夜变化贡献率最大；3）生态因子（光强和气温）和叶片形态结构（叶厚度、比叶重、单位面积含氮量和含碳量）对碳收支指标空间变异没有显著的独立贡献率，各影响因子之间的交互贡献率较高。采用CEZ分区方法，本研究基于叶片指标外推估算了冠层光合作用产量，估算结果显示，用功能特性相对稳定的功能区表达异质性特点，有效减少了冠层碳收支总量估算的误差，弥补了以往估算方法的部分不足。 晴天和阴天天气条件下冠层生态分区不同、叶片对环境因子的响应不完全一致，昼夜碳收支总量也有差异，散射光比重差异是这些差异的主要原因之一。为此，我们研究了叶片近、远轴面气体交换指标对直射光和散射光的差异，进一步探索了异面叶（日本晚樱）和等面叶（高粱）在叶片水平对直射光和散射光响应的背腹侧适应、以及田间条件下光合作用对晴天和阴天的光适应调控策略。结果表明，直射光和散射光的光质差异、气孔敏感性差异以及叶片的光吸收差异使其在叶片光合碳同化速率中的作用存在差异。而叶片近、远轴面气孔密度、叶肉细胞光化学活性等差异，使叶片近、远轴面对直射光和散射光的响应不同。田间条件下，等面叶通过对不同光的利用调节整体光合作用，而异面叶调节作用较弱。叶片对直射光和散射光的响应研究有助于理解在单叶水平上不同类型叶片近、远轴面对光环境的响应特征，并为等面叶光能利用效率在晴天和阴天的差异提供了数据支持。 |
| 英文摘要 | Carbon budget of plants is crucial to the ecosystem carbon balance. Canopy carbon budget accounts for most of the plant gas exchange, and is the most commonly studied component. The calculation of available carbon budget in plant crown is essentially a scaling problem. The leaf gas-exchange response to ecological factors, has been studied in great detail and is generally well understood. The major outstanding issue is how to scale the short-term leaf-level response of gas-exchange upto crown level. Understanding temporal and spatial heterogeneities of ecological factors and leaf traits on a crown scale is a prerequisite for accurately and quantitatively predicting carbon budget of a crown. With this in mind, we developed an ecological technique of spatial zoning of crown based on the diurnal variations of light intensity (I), air temperature (T), air relative humidity (RH) and CO2 concentration (Cair). So the temporal and spatial heterogeneities of them on a crown scale were clarified: i) there was no statistically significant horizontal differentiation of hourly T, I, RH and Cair whether under sunny or cloudy weather condition; ii) the vertical differentiation of crown ecological factors only appeared in T under sunny condition and I under both weather conditions; iii) crown spatial heterogeneity of T was observed only in a special period（9:00 to 15:00 for a day）, but that of I could be observed during 6:00 to 18:00 at a diurnal scale ; iv) different from the past results of study achieved in the international literatures, T and I are not continuously and exponentially decreased with vertical crown depths, but decreased by a discrete spatial gradient pattern consisting of different CEZs. Based on the 4-CEZs gradient patterns of ecological factors and leaf traits observed in this study, the temporal and spatial heterogeneity of photosynthetic rates (Pn) and respiration rate (Rd) for crown leaf and the influencing factors was investigated, we achieved the following conclusions: i) temporal heterogeneity of Pn and Rd on a diurnal scale was directly affected by the temporal and spatial heterogeneities of T and I; ii) T, I and RH had significant independent contributions to temporal heterogeneity of Pn and Rd under sunny condition while only I had significant independent contribution under cloudy condition; iii) spatial heterogeneity of Pn and Rd on a crown scale was influenced by some ecological factors (T and I) and leaf structural traits, but variations of Pn and Rd was affected more by the joint rather than the independent contributions, and carbon concentration per leaf area (Ca) had the highest total contribution (Independent + Joint) among all influencing variables both under sunny and cloudy conditions. Including the change of weather conditions and differences of distribution of spatial areas or CEZs at a crown scale in the analysis of crown ecological functioning can reduce the estimation errors of carbon budget for crown. The new technique of ecological zoning for crown ecological factors and the 4-CEZs gradient patterns under different weather conditions developed and established in this study can provide a better methodological platform for studying other species of tree and crown type, and effectively or powerfully identifies crown spatial heterogeneity. The diffuse fraction of incident light plays important roles in the difference of crown trait between two weather conditions. Thus, we investigated the response of leaf gas exchange to direct and diffuse light, and further studied the dorsoventral acclimation to direct and diffuse light in the open field conditions. Our results showed that light quality, stomatal sensitivity, and leaf absorption played important roles in the contribution of adaxial surface and abaxial surface to leaf integrated carbon assimilation. The response of leaf adaxial and abaxial surface to direct and diffuse light was greatly different because of the variation of stomatal density and primary photochemical activity. The isolateral leaves regulated the integrated carbon assimilation better than bifacial leaves by adjusting light use of two leaf surfaces. These results are helpful to understanding light response of adaxial and abaxial surfaces in isolateral bifacial leaves to direct and diffuse light, and provide data evidence for the difference of light use efficiency in sunny and cloudy days. |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/37022]  |
| 专题 | 生态环境研究中心_城市与区域生态国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 王晓琳. 城市典型植物冠层异质性对叶片和冠层 碳收支的影响[D]. 北京. 中国科学院研究生院. 2016. |
入库方式： OAI收割
来源：生态环境研究中心
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