模拟增温对黄河三角洲滨海湿地土壤呼吸的影响

	模拟增温对黄河三角洲滨海湿地土壤呼吸的影响
	孙宝玉1,2
学位类型	硕士
导师	韩广轩 ; 甄晓杰
	2017-05-14
学位授予单位	中国科学院大学
学位授予地点	北京
关键词	增温土壤呼吸土壤盐分地表淹水滨海湿地黄河三角洲
其他摘要	土壤呼吸是土壤向大气碳输入的主要途径，在全球碳循环中发挥着重要作用。据预测，未来100年全球平均地表温度将上升0.3－4.8 ℃，温度的升高会影响土壤呼吸从而改变全球碳平衡。滨海湿地中的“蓝碳”是地球上最密集的碳汇之一，在应对气候变化方面起着重要作用。由于滨海湿地地下水位浅、淡咸水交互作用明显，增温一方面能够直接影响土壤呼吸，另一方面能够通过影响水盐动态间接影响土壤呼吸。因此，我们选择黄河三角洲滨海湿地为研究对象，采用红外辐射加热器模拟增温，研究了该地区环境因子、生物因子以及土壤呼吸的变化规律，同时探讨了土壤呼吸对增温的响应机制，最终定量评估了增温对黄河三角洲滨海湿地土壤呼吸的影响。根据土壤含水量不同，将全年分成3个时期（干旱期、湿润期、淹水期）。增温对土壤呼吸速率的影响在不同时期表现不同。干旱期，温度升高2.2 ℃，土壤呼吸速率降低了15.3%；湿润期，温度升高2.0 ℃，土壤呼吸速率提高23.9%；淹水期，增温对土壤呼吸速率无显著影响。全年尺度上，增温2.0 ℃，土壤呼吸提高11.3%。增温对土壤呼吸的影响是通过环境因素以及生物因素的改变实现的。不同时期（干旱期、湿润期、淹水期）环境因素对土壤呼吸速率的影响机制不同。干旱期，增温温引起的土壤盐分的升高限制了土壤呼吸；湿润期，由于不存在盐胁迫，温度的升高促进了土壤呼吸的产生；淹水期，长期土壤水分的过饱和状态影响了增温效果，使得土壤呼吸速率在增温与对照中无显著差异。而增温造成生物量的增加通过影响凋落物量等促进了土壤呼吸。不同时期的光合速率对土壤呼吸也产生了一定的影响。干旱期，增温造成的光合速率的下降降低了土壤呼吸，湿润期芦苇光合速率的提高刺激了土壤呼吸的产生，而在淹水期植被的光合作用以及土壤呼吸作用均受到积水限制，温度的升高对其影响不显著。相关分析表明无论增温还是对照，土壤呼吸速率均与土壤温度表现出较强的相关性，是其主导因子。然而不同时期（干旱期、湿润期、淹水期）由于土壤盐分的不同造成土壤呼吸速率对温度的响应不同。因此对土壤呼吸与温度的关系进行分阶段拟合：盐分限制阶段(土壤盐分含量> 5.0 ds·m^–1)方程为SR= 0.081e^0.117T（r² =0.69, p<0.001）；非盐分限制阶段(土壤盐分含量< 5.0 ds·m^–1)，方程为SR= 0.195e^0.106T（r² =0.89, p<0.001）。而对照小区全年与各个阶段的拟合效果相似，因此，其方程为：SR= 0.191e^{0.104 T}（r² =0.84, p<0.001）。模拟估算表明，干旱期增温使黄河三角洲滨海湿地土壤呼吸降低了21.6%，湿润期增温使土壤呼吸增加了51.5%，淹水期无明显差异；在全年尺度上，增温使土壤呼吸提高了32.7%。 ; Soil respiration (Rs) is the major efflux of carbon dioxide (CO₂) from terrestrial ecosystem to the atmosphere. Furthermore, increasing Rs caused by increasing temperature can result in significant changes in the global carbon balance. Climate change due to greenhouse gas emissions is predicted to raise the mean global temperature by 0.3–4.8°C in next 100 years. Therefore, the response of Rs to experimental warming is one of the key challenges in global change research. The "blue carbon" of the coastal wetland is one of the most intensive carbon sinks on the earth, plays an important role in tackling climate change. The coastal wetland has shallow underground water level and is affected by the fresh water and salt water. On the one hand, elevated temperature can directly increase the rate of Rs. On the other hand, elevated temperature can also indirectly influence Rs by affecting environmental factors (e.g., soil water, soil salt, soil physical and chemical properties) and biological factors (e.g., photosynthesis, litter decomposition). So we used a complete random block design with 2 treatments (control, warming), and replicated 4 times in a coastal wetland in the Yellow River Delta. All the warmed plots were heated by infrared heaters. We analyzed the variation of environmental factors, biotic factors and soil respiration, discussed the mechanisms in acclimatization of soil respiration to warming, and evaluated the effect of warming on soil respiration in a coastal wetland in the Yellow River delta. The effects of warming on soil respiration was different during different periods (the drought period, the wet period and the flooding period). The soil respiration in the control was higher than that in the warming during the drought period (2.2 ℃ soil temperature increased, 15.3% reduction in soil respiration), contrarily during the wet period(2.0 ℃ soil temperature increased, 23.9% simulation in soil respiration). During the flooding, there were no significant differences between the two treatments. During the whole year, warming simulated the soil respiration by 11.3%. The effects of warming on soil respiration had different mechanisms during different periods (the drought period, the wet period and the flooding period). During the drought period, soil respiration was decreased in the warming plot due to the increased soil salt content on the one hand. On the other hand, the high salt content desreased the soil respiration by limiting the photosynthesis of Phragmites australis. During the wet period, soil temperature is the main factor which affected the soil respiration directly and through simulating the photosynthesis indirectly. Whereas during the flooding period, there were no differences on soil temperature, soil salt content, photosynthesis and soil respiration between warming and control. At the same time, the increased biomass could stimulate the soil respiration. The predominant factor which affected the soil respiration was soil temperature through the related analysis no matter it was warming plot or control plot. However, the relationship between soil respiration and soil temperature was different during the different periods (the drought period, the wet period and the flooding period) due to the salt restriction. Under warming plot, when soil salt content >5.0 ds·m^–1, we developed the equation SR= 0.081e^0.117T(r² =0.69, p<0.001); When soil salt content <5.0 ds·m^–1, equation was SR= 0.195e^0.106T(r² =0.89, p<0.001. Under the control plot, the relationship between soil respiration and soil temperature was similar during the different periods, so the equations was SR= 0.191e^{0.104 T}(r² =0.84, p<0.001). According to the model, we got that warming increased the soil respiration of coastal wetland of the Yellow River delta by 32.7% (warming was 2174.6 g · m ^-2, control was 1660.0 g · m^-2) in 2015. The soil respiration was different during the different periods. During the drought period, warming decreased soil respiration by 21.6%. During the wet period, warming simulated soil respiration by 51.5%. There was no difference between warming and control during the flooding period.
文献类型	学位论文
条目标识符	http://ir.yic.ac.cn/handle/133337/21997
专题	中国科学院烟台海岸带研究所知识产出_学位论文
作者单位	1.中国科学院烟台海岸带研究所 2.中国科学院大学
第一作者单位	中国科学院烟台海岸带研究所
推荐引用方式 GB/T 7714	孙宝玉. 模拟增温对黄河三角洲滨海湿地土壤呼吸的影响[D]. 北京. 中国科学院大学,2017.

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