Knowledge Resource Center for Ecological Environment in Arid Area
| 青藏高原不同草地下垫面CO2通量变化特征及其分布研究 | |
| 其他题名 | Study on CO2 Flux Variation Characteristics and Distribution over the Different Grassland surface of the Tibetan Plateau |
| 朱志鹍 | |
| 出版年 | 2015 |
| 学位类型 | 博士 |
| 导师 | 胡泽勇 ; 马耀明 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 陆地生态系统碳收支及其循环过程的研究一直都是全球变化研究中的热点问题。草地生态系统是全球分布最广的生态系统类型之一，它的碳收支状况对全球碳核算起着重要的作用。青藏高原平均海拔4000m以上，是对全球变化响应敏感的地区。高原地区草地面积约占48%，开展对青藏高原典型草地生态系统CO2通量时空变化特征的研究，对于探明高寒草地生态系统的碳源汇状况、碳循环过程具有重要意义。 本文依托中国科学院青藏高原研究所纳木错圈层相互作用综合观测研究站（以下简称纳木错站，英文简称NAMORS）、阿里荒漠环境综合观测研究站（以下简称阿里站，英文简称NASDE）和中国科学院寒区旱区环境与工程研究所那曲高寒气候环境观测研究站（以下简称那曲站，英文简称NaPlaCE），基于涡动相关技术对高寒草原、荒漠草原、高寒草甸生态系统的CO2通量进行长期连续观测，对观测数据进行了严格的质量控制和质量评价，分析了CO2通量的日变化、季节变化和年变化特征及其影响因子，获得了以下研究结果： 1.利用EdiRe和TK3两种软件计算湍流通量，发现结果非常一致，TK3计算的感热、潜热、二氧化碳通量略低些，但即便对较难测量精确的潜热通量和CO2通量，差异也在7%以内。 2.高寒草原、高寒草甸和高寒荒漠草地的CO2通量存在相似的日变化、季节变化特征。生长季节6~9月，CO2通量呈现单谷的吸收模式，三种草地月平均的CO2日最大吸收速率分别为-3.9 、-5.3、-3.7μmol m-2 s-1，高寒草甸明显要高于其他两种草地类型。这三种草地生态系统在生长季表现为明显的碳汇，在生长季6~9月份，这三种草原碳吸收量由高到低分别为高寒草甸（123.34 g C m-2）>荒漠草原（105.66 g C m-2）>高寒草原（58.54 g C m-2）。但是从全年来看，纳木错高寒草原为弱小的碳源，2008和2009年碳排放量分别为23.2和38.3 g C m-2；而高寒草甸生态系统为明显的碳汇，年吸收量为41.3 g C m-2，但碳吸收量明显少于高原东部海拔相对较低的草地和纬度相近的平原地区的草地生态系统。 3.纳木错高寒草原生态系统日累积NEE与地上生物量有着明显的线性关系，2007年生长季这种线性关系为NEE = (-0.005±0.0018) ×AGB + (0.1230 ± 0.1752 ), R2=0.54；2008年生长季NEE = (-0.0073 ± 0.0027) × AGB + (0.0533 ± 0.2049), R2=0.52。超过50%的NEE日累积量的变化可以由地上生物量的变化来解释，与世界其他草地研究结果一致。从RE与GPP的日累积量来看，两者有着非常好的相关关系，这三种草地生长季，GPP可以解释50%以上的RE的变化。在降水较为充沛的年份，生长季的光合作用明显主导着呼吸作用（R2>0.73）。全年RE占GPP的比重较高，这表明生态系统通过光合作用固定的碳，大部分通过呼吸作用消耗掉。 4.利用Michalis-Menten光响应方程，拟合得到高寒草原、高寒草甸、荒漠草原三种草地的生长旺盛期的α值分别为-0.0370、-0.0255、-0.010 ?mol CO2· ?mol-1 photons。阿里荒漠草原在生长季各月，NEE主要受到PAR控制（生长季各月R2在0.63以上）。高寒草原NEE则受到在土壤水分和PAR的共同影响，在土壤水分适宜时，NEE和光合有效辐射（PAR）有较好的直角双曲线关系，表观光量子效率α可以达到0.0370 ?mol CO2· ?mol-1 photons。当土壤含水量较低时，α绝对值也明显减小，且NEE和光合有效辐射的关系也变得不显著。有云情况时，生态系统碳吸收增加的并不明显。 5.生态系统的呼吸作用同时受到温度和土壤水分的影响。高寒草原和高寒草甸的温度敏感性Q10值均高于2.0，表明高寒草地生态系统对未来气候变暖的敏感性。高寒草原的Q10值随着土壤水分的降低而减小，表明土壤水分调节高寒草原CO2排放过程，旱季不利于其排放，并降低温度敏感性。 6.那曲高寒草甸生长季昼夜温差与NEE呈负相关关系，NEE = -0.16 ? 0.04 (Tmax-Tmin) -2.62 ?0.49, R2=0.14, P< 0.001，这表明昼夜温差大有利于该草地生态系统的碳累积；而其他两个站草地昼夜温差和碳累积没有明显的关系。 7.对高寒草原来说，雨季来的较早且降水比较丰沛的年份，生长季碳吸收量要明显高于降水较少年份。降水的季节分配和年际变化对草地生态系统的碳收支状况有着重要的影响。生长季末期的降水会提高生态系统的呼吸作用，消耗固定的碳，对生态系统碳收支有重要影响。 |
| 英文摘要 | Grasslands are one of the most widespread ecosystems in the world. They cover nearly one fifth of the Earth’s land surface. Therefore, they play an important role in the total carbon exchange between the biosphere and the atmosphere. The northern grassland ecosystems in particular, may behave as a significant carbon sink, balancing the carbon budget of the global terrestrial ecosystem. The Tibetan Plateau, with an average elevation of over 4000 m, is the highest grassland plateau in the world. The area of alpine grassland is 48% of the plateau. Assessing the carbon dioxide (CO2) flux and its environmental controls in these ecosystems will not only contribute to an improved understanding of the basic carbon cycle processes, but will also provide important information for quantifying the carbon budget of the terrestrial region The net ecosystem carbon dioxide (CO2) exchange (NEE) between the atmosphere and an alpine steppe, alpine meadow and alpine desert ecosystem was measured by the Eddy Covariance (EC) method. The results show that: 1. There was no significant difference between the results calculated by EddiRe and TK3 software. The H, LE and CO2 flux calculated by TK3 were a little less than EddiRe. But the difference was no more than 7%. 2. The CO2 flux of alpine steppe, alpine meadow and alpine desert has similar diurnal, seasonal variance. The diurnal amplitude of NEE varied substantially during the growing seasons. The maximum CO2 uptake rates of the grasslands were -3.9 、-5.3、-3.7 μmol CO2·m-2·s-1, respectively. The accumulated NEE from June to September were 123.34, 105.66 and 58.54 g C m-2 for alpine meadow, desert and steppe, respectively. The alpine meadow was a carbon sink and uptake 41.3 g C m-2 during the whole year. This indicated that the alpine meadow had lower carbon sequestration potential comparing with other grasslands. In contrast, the alpine steppe was a weak carbon source in 2008 and 2009 and released 23.2 and 38.3 g C m-2, respectively. 3. For the alpine steppe ecosystem, the daily NEE responded to AGB in a linear manner. In 2007, the relationship was NEE = (-0.005±0.0018) ×AGB + (0.1230 ± 0.1752 ), R2=0.54. In 2008, the relationship was NEE = (-0.0073 ± 0.0027) ×AGB) + (0.0533±0.2049), R2=0.52). Fifty-two percent of the NEE variance could be explained by the variance of AGB. The daily integrated RE and GPP has a good relationship. During the growing season, the GPP could explain more than 50% variance in RE. This indicated that the canopy photosynthesis controlling the substrate availability for the autotrophic and heterotrophic repiration through roots exudates. 4. Based on the Michalis-Menten equation, the apparent quantum yield (α) was derived. During the quick growing period, the α were -0.0370、-0.0255、-0.010 ?mol CO2· ?mol-1 photons for alpine steppe, meadow and desert ecosystem. The daytime NEE was strongly controlled by PAR in alpine desert (R2>0.63). The soil moisture and PAR influenced the NEE together. The lower α under low soil water condition was likely due to reduced carbon assimilation when the grass was under water stress. The α value could increase to 0.0370 ?mol CO2· ?mol-1 photons while the soil moisture was appropriate in August 2008. 5. The temperature and soil moisture determined the alpine steppe respiration. Q10 of the alpine meadow and steppe were both above 2, which indicated the alpine grassland systems were sensitivity to the global warming. The value of Q10 decreased with the soil moisture, which suggested it could regulate the CO2 release progress. Water stress may depress the temperature sensitivity. 6. The NEE has negative correlation with temperature difference between day and nigh. NEE = -0.16 ? 0.04 (Tmax-Tmin) -2.62 ?0.49, R2=0.14, P< 0.001. This indicate the high temperature difference could lead to more carbon uptake. Such correlation was not found in the other grasslands. 7. The alpine ecosystem could assimilate more CO2 during the growing season as the rainfall was enough. The seasonal allocation and variance of precipitation has obviously influence to the carbon balance. |
| 中文关键词 | 青藏高原 ; 高寒草地 ; 涡动相关 ; 生态系统CO2净交换 ; 总初级生产力 ; 环境影响因子 |
| 英文关键词 | Tibetan Plateau alpine grassland eddy covariance net ecosystem carbon exchange gross primary production environment factors |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 大气物理学与大气环境 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287530 |
| 推荐引用方式 GB/T 7714 | 朱志鹍. 青藏高原不同草地下垫面CO2通量变化特征及其分布研究[D]. 中国科学院大学,2015. |
| 条目包含的文件 | 条目无相关文件。 | |||||
| 个性服务 |
| 推荐该条目 |
| 保存到收藏夹 |
| 导出为Endnote文件 |
| 谷歌学术 |
| 谷歌学术中相似的文章 |
| [朱志鹍]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [朱志鹍]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [朱志鹍]的文章 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
