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植物功能性状对群落碳水通量的影响: 以黄土高原半干旱草地为例
Alternative TitlePlant Functional Traits Contribute to Community Carbon and Water Fluxes:A Case Study of Semiarid Grassland in Loess Plateau
王梦宇
Subtype硕士
Thesis Advisor傅伯杰 ; 吕楠
2018-06
Degree Grantor中国科学院生态环境研究中心
Place of Conferral北京
Degree Name理学硕士
Degree Discipline生态学
Keyword半干旱草地,碳水通量,土壤含水量,植物性状,功能多样性 Semiarid GrasslAnd, Carbon And Water Fluxes, Soil Water Content, Plant Trait, Functional Diversity
Abstract

      草地占全球陆地面积的近40%,具有巨大的固碳潜能,对于调节区域及全球碳收支和能量平衡发挥着重要作用,影响生态文明建设和社会经济发展。研究植物功能性状对草地碳水通量的影响,可以帮助我们理解生物多样性与生态系统功能关系的潜在机制,量化多样性对生态系统功能的影响,预测生态系统碳水通量并提高模型的精确度。通过调整植物群落的功能结构可以控制重要的生态系统功能,对区域的植被建设和生态管理提供了一定的理论基础和方法支持。

       本研究通过静态同化箱法测定黄土高原半干旱丘陵沟壑区5种典型草地群落生长季的碳水通量,包括生态系统净交换(Net ecosystem exchange, NEE)、生态系统呼吸(Ecosystem respiration, ER)、总生态系统生产力(Gross Ecosystem Productivity, GEP)和蒸散发(Ecosystem evaportranspiration, ET),同时测定环境参数和植物功能性状,并计算功能性状的群落加权平均值和功能离散度,分析环境条件和植物功能性状特征对草地生态系统碳水通量时间动态的贡献。

     研究结果发现:

    (一)不同类型草地的碳水通量在生长季变化趋势大致相同,整体均呈现单峰变化趋势,峰值一般出现在7月下旬。碳、水通量的时间动态与土壤水分含量的时间动态具有一致性的变化规律,表明草地碳水通量对土壤水分变化有较高的响应敏感性。

    (二)不同类型草地的碳通量存在显著差异,其中铁杆蒿的NEE、ER和GEP均高于其他群落,表现出较强的固碳能力;而5种类型草地的ET未表现出显著性差异。

    (三)影响生长季5种草地类型碳水通量的环境因子主要有土壤含水量、土壤温度、空气温度和相对湿度。环境因子对碳水通量的解释度达13.6 %~85.8 %,土壤含水量对碳水通量的解释度达5.9 %~63.1 %。

    (四)考虑功能性状指标后明显提高了4个碳水通量多元回归模型的解释度。比叶面积和叶片δ13C含量的群落加权平均值(CWM_SLA和CWM_Lδ13C)分别对NEE、ER、GEP和ET模型的解释度提高了18.0 %、6.3 %、8.0 %和30.5 %。

     (五)所有功能性状离散度参数(FDvar)对4个碳水通量变量的时间变异都没有显著影响。本研究的结果表明,碳水通量主要受群落中优势物种功能性状的影响,功能性状离散度在此的作用并不明显。因此,本研究结果支持生物量比假说,不支持互补效应假说。

Other Abstract

    About 40% of the global terrestrial area is covered by grassland, which has a huge potential for carbon sequestration and plays an important role in regulating regional and global carbon budgets and energy balances, further affecting the construction of ecological civilization and socioeconomic development. Studying the contributes of plant functional traits to grassland carbon and water fluxes can help us understand the underlying mechanisms of the relationship between biodiversity and ecosystem functions, quantify the impact of diversity on ecosystem functions, and improve the accuracy of prediction models. Ecosystem functions can be controlled by adjusting the functional structure of plant communities, which can provide certain theoretical foundations and methodological supports for regional vegetation construction and ecological management.

     In this study, we monitored carbon and water fluxes of five typical grassland communities in the semi-arid gully area of the Loess Plateau by using the closed chamber technique over a growing season, including net ecosystem exchange (NEE), ecosystem respiration (ER), gross ecosystem productivity (GEP) and ecosystem evapotranspiration (ET). environmental parameters and plant functional traits were measured simultaneously. Community weighted mean (CWM) and functional variance (FDvar) were calculated based on plant functional traits. Then analysed the contributions of environmental factors and plant functional traits to the dynamic of grassland carbon and water fluxes.

     The major findings of this dissertation are as follows:

     (1) The general variation trends of these flux variables were similar among the five types of grassland with the peak values occurred in late July. It was obvious that the dates with the highest fluxes were consistent with those of the highest soil water content, which indicated rapid responses of the fluxes to soil water content changes.

    (2) The mean NEE, ER, GEP over the growing season were significantly higher in ASA than in other communities, showing stronger carbon sequestration capacity. The mean ET of the main growing season had no significant difference among the five grassland types.

    (3) The environmental factors affecting the carbon-water flux of the five grassland types in the growing season mainly include soil moisture content, soil temperature, air temperature, and relative humidity. The interpretations of environmental factors to carbon and water fluxes were 13.6% to 85.8%, of which the soil water content accounted for 5.9 % to 63.1 %.

    (4) Inclusion of the plant trait measures greatly improved the degree of explanation in the multi-regression models. CWM values of specific leaf area (CWM_SLA) and leaf δ13C content (CWM_Lδ13C) improved the interpretations of net ecosystem exchange (NEE), ecosystem respiration (ER), gross ecosystem productivity (GEP) and evapotranspiration (ET) by 18.0 %, 6.3 %, 8.0 % and 30.5 %, respectively.

    (5) None of the FDvar indices were significantly correlated with the carbon and water flux variables in our study.

    The results of this study indicate that the carbon and water fluxes are mainly affected by the traits of dominant species in the community, but the effect of the functional variance at community level is not evident here. Therefore, we demonstrate the logic of biomass ratio hypothesis in explaining the relationships between traits and ecosystem processes, but did not support the hypothesis of complementary effects.

Pages75
Document Type学位论文
Identifierhttp://ir.rcees.ac.cn/handle/311016/41537
Collection城市与区域生态国家重点实验室
Recommended Citation
GB/T 7714
王梦宇. 植物功能性状对群落碳水通量的影响: 以黄土高原半干旱草地为例[D]. 北京. 中国科学院生态环境研究中心,2018.
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