开垦对黄河三角洲芦苇湿地净生态系统CO2交换过程的影响
文献类型：学位论文
| 作者 | 杨利琼 |
| 学位类别 | 硕士 |
| 答辩日期 | 2013-05-28 |
| 授予单位 | 中国科学院大学 |
| 授予地点 | 北京 |
| 导师 | 韩广轩 |
| 关键词 | 涡度相关法 净生态系统CO2交换 开垦 芦苇湿地 黄河三角洲 |
| 学位专业 | 环境科学 |
| 中文摘要 | 滨海湿地由于其较高的CO2固定能力和较低的CH4释放过程，使其成为全球碳循环中的重要碳汇地区。而黄河三角洲滨海湿地是世界上受海陆作用共同影响的活跃地区之一，近年来，由于人类的不合理利用，黄河三角洲自然湿地被大面积的垦殖为农田，导致湿地生态系统碳循环的模式发生改变，从而影响其碳汇功能。目前，关于开垦对黄河三角洲滨海湿地净生态系统CO2交换过程的研究还鲜有报道，所以本研究通过涡度相关法，对黄河三角洲芦苇湿地生态系统和开垦多年的农田(棉花)净生态系统CO2交换 (NEE)进行了对比观测，以探讨该地区典型生态系统CO2交换的变化规律及其影响因子，揭示开垦对芦苇湿地生态系统CO2交换和碳汇功能的影响。结果表明: 1) 生长季中，湿地和农田生态系统NEE日平均值各月均呈明显的“U”型变化曲线，非生长季NEE变幅很小。在2011年，湿地于7月NEE日平均值达到极值(–0.44 ± 0.03) mg CO2·m–2·s–1，而农田生态系统在8月到达极值(–0.44 ± 0.04) mg CO2·m–2·s–1。夜间湿地生态系统排放最大值出现在7月，为(0.16 ± 0.01) mg CO2·m–2·s–1，而农田生态系统夜间排放最大值出现在8月，为(0.14 ± 0.01) mg CO2·m–2·s–1。在2012年，农田生态系统白天NEE的极值和夜间最大的排放值均于7月达到极值，分别为(–0.41 ± 0.01) mg CO2·m–2·s–1和(0.14 ± 0.01) mg CO2·m–2·s–1。2) 2011-2012年，黄河三角洲湿地和农田生态系统NEE、生态系统呼吸(Reco) 、生态系统总初级生产力(GPP)的季节变化均呈5~10月较高，1~4月和11~12月较低的分布。2011年，湿地生态系统日GPP和 Reco的极值分别为7月11日的–24.78 g CO2·m–2·d–1和8月9日的14.95 g CO2·m–2·d–1，而日NEE的极值出现在8月17日的–16.04 g CO2·m–2·d–1；农田生态系统日GPP和 Reco的极值分别为–27.81 g CO2·m–2·d–1(8月17日)和12.23 g CO2·m–2·d–1(7月29日)，而日NEE的极值出现在–18.99 g CO2·m–2·d–1(8月22日)。在2012年的农田生态系统中， GPP 、Reco和NEE日极值分别出现在–31.66(7月27日)、14.29 (7月25日) 和–19.18 g CO2·m–2·d–1(7月27日)。 3) 生长季白天两个生态系统NEE与光合有效辐射之间呈直角双曲线关系；非生长季NEE主要受土壤温度的影响；生态系统生长季夜间NEE受土壤温度和土壤体积含水量的共同影响；2011年湿地和农田生态系统呼吸温度敏感性参数(Q10)分别为2.30和3.78，而2012年生长季农田生态系统的Q10为3.03。在2011年，地上生物量对湿地和农田生态系统的NEE、Reco、GPP的相关性不显著(P>0.05)；而在2012年生长季的前期，地上生物量和叶面积指数(LAI)均与NEE、Reco、GPP的关系显著(P<0.05)。 4) 2011年生长季，黄河三角洲湿地和农田生态系统均表现为CO2的汇，总净固碳量分别为780.95和647.35 g CO2·m–2，开垦降低了湿地的碳吸收能力；非生长季，湿地和农田生态系统均表现为CO2的源，总释放量分别为181.90和111.55 g CO2·m–2。2012年生长季农田总净固碳量约为600.18 g CO2·m–2，而在非生长季，农田生态系统释放了115.79 g CO2·m–2。在2012年农田生态系统总净固碳量约为484.39 g CO2·m–2。就2011年全年而言，湿地和农田生态系统总净固碳量差异不大，分别为599.05和535.80 g CO2·m–2。 |
| 英文摘要 | Coastal wetlands play important role as natural carbon sinks in the global carbon cycle because of their higher rates of CO2 sequestration and lower CH4 emissions. As a typical coastal wetland, the Yellow River Delta is one of the most active regions of land-ocean interaction in the world. Unfortunately, it has been undergoing extensive and rapid development of agriculture over recent decades, which might change its carbon sequestration and budget. However, few studies to date have focused on reclamation effect of net ecosystem carbon exchange over coastal wetlands in the Yellow River Delta. Using the Eddy Covariance (EC) technique, we measured ecosystem CO2 exchange fluxes and their environmental and biological factors in reed wetland and cropland ecosystems. Our objective was to investigate the effects of wetland reclamation on ecosystem CO2 exchange dynamics and quantify CO2 exchange of the two ecosystems response to environmental and biological factors.Results showed: 1) The U type curve was showed in different months of growing season between wetland and cropland ecosystems while little change in non-growing season. During growing season in 2011, the maximum of the averaged daily CO2 uptake and release rate in wetland ecosystem were (0.44 ± 0.03) and (0.16 ± 0.01) mg CO2·m–2·s–1, respectively, while the maximum of the averaged daily CO2 uptake and release rate in cropland ecosystem were (0.44 ± 0.04) and (0.14 ± 0.01) mg CO2·m–2·s–1, respectively. During growing season in 2012, the maximum of the averaged daily CO2 uptake and release rate in cropland ecosystem were (0.41 ± 0.04) and (0.14 ± 0.01) mg CO2·m–2·s–1, respectively.2) Analyses of NEE, ecosystem respiration (Reco) and gross primary productivity (GPP) in 2011 and 2012, showed that During the growing season, the values of GPP, Reco and NEE were higher during the peak growing season (from July to September) and lower during the initial (from January to June) and late (from October to December) month. In 2011, The extreme values of GPP, Reco, NEE over wetland ecosystem were –27.81(July 11), 14.95(August 9), –16.04(August 17) g CO2·m–2·d–1 , respectively, while in cropland ecosystem, the extreme values of GPP, Reco, NEE were –28.81(August 17), 12.23(July 29), –18.99(August 22) g CO2·m–2·d–1, respectively. In 2012, the cropland’s extreme values of GPP, Reco, NEE were –31.66(July 27), 14.29(July 25) and –19.18(July 27) g CO2·m–2·d–1, respectively. 3) Daytime NEE values were strongly correlated with photosynthetic active radiation (PAR) in growing season; the NEE was strongly affected by the temperature of soil (Ts) in non-growing season. Volumetric soil moisture (SWC) and Ts were the main factors affecting the nighttime NEE in growing season; the temperature sensitivity of ecosystem respiration (Q10) were 2.30 (wetland) and 3.78 (cropland) during the growing season in 2011, while in 2012, the cropland ecosystem’s Q10 was 3.03; the wetland and cropland ecosystems had no significant correlation with NEE, Reco, GPP and aboveground biomass in 2011(P>0.05); but in 2012, the cropland ecosystem had significant correlation between NEE, Reco, GPP and aboveground biomass as well as leaf area index (LAI) during early growing season in 2012(P<0.05).4) During growing season in 2011, the wetland and cropland ecosystems were carbon sinks as they absorbed 780.95 and 647.35 g CO2·m–2, respectively, which meaned that the wetland reclamation can reduce its carbon sequestration ability. During non-growing season in 2011, both ecosystems expressed as the carbon sources releasing 181.90 (wetland ecosystem) and 111.55 (cropland ecosystem) g CO2·m–2, respectively. In 2012, the cropland ecosystem absorbed 600.18 g CO2·m–2 in growing season and released 115.79 g CO2·m–2 in non-growing season. Therefore, The cropland ecosystem in 2012 was a carbon sink with absorption of 484.39 g CO2·m–2. In 2011, the wetland and cropland ecosystems were both obvious carbon sinks with absorption of 599.05 and 535.80 g CO2·m–2, respectively, which differs little. |
| 学科主题 | 环境科学 |
| 语种 | 中文 |
| 公开日期 | 2013-08-14 |
| 源URL | [http://ir.yic.ac.cn/handle/133337/6377]  |
| 专题 | 中科院烟台海岸带研究所知识产出_学位论文 |
| 推荐引用方式 GB/T 7714 | 杨利琼. 开垦对黄河三角洲芦苇湿地净生态系统CO2交换过程的影响[D]. 北京. 中国科学院大学. 2013. |
入库方式： OAI收割
来源：烟台海岸带研究所
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