IMHE OpenIR  > 山地表生过程与生态调控重点实验室
川西高原高寒草甸温室气体排放对降水变化的响应
Alternative TitleThe Response of Greenhouse Gas Emissions to Precipitation Changes in an Alpine Meadow in the Western Sichuan Plateau
Language中文
谢青琰
Thesis Advisor高永恒
2016
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name硕士
Degree Discipline环境工程
Keyword人工模拟 降水 温室气体 高寒草甸 青藏高原
Other Abstract

随着全球变化问题的出现,不同时空尺度下的物质、能量、水分、养分循环等均发生了一系列变化,而这些变化又会反过来作用于地球表层系统(大气、水体、土壤、植被等),从而加剧全球变化的发展。大量的科学研究和实地观测表明,青藏高原的气候模式已发生不同程度的时空变化,其中降水强度和格局的改变(增加或减少)对青藏高原内部生态系统稳定性、养分物质的储存和运移、温室气体通量以及社会经济、居民生活等都带来影响。高寒草甸生态系统是青藏高原上广泛分布的天然草地类型,是陆地生态系统中一个十分重要的碳库,对于青藏高原乃至全球气候变化、温室气体排放以及碳的地球化学生物循环都具有重要意义。因此,在未来全球变化的大背景下,尤其是降水的变化,使得青藏高原高寒草甸生态系统温室气体排放模式发生改变,并且高寒草甸对于全球变化的贡献和在其中所扮演的角色也将相应的做出改变。本研究以青藏高原东部的高寒草甸生态系统为对象,通过野外模拟不同强度降水(增加200 mm,减少200 mm以及自然降水量作为对照),采用静态箱-气象色谱法观测了植物生长季内(5月~ 9月)高寒草甸温室气体排放通量的变化情况,初步明确了不同强度降水下高寒草甸温室气体排放的动态特征和变化规律,揭示高寒草甸生态系统对短期降水变化的响应机制,同时研究了在增加降水后,高寒草甸温室气体排放的日变化特征,以期为将来在全球变化的大背景下,对高寒地区生态系统温室气体排放进行评估与管理提供科学依据。主要有以下结果:(1)不同降水处理间的土壤温度、可溶性碳(DOC)、可溶性氮(DON)、铵态氮(NH4+-N)和硝态氮(NO3--N)含量均无显著差异。但在生长季刚开始的5月份,DOC、DON、NH4+-N和NO3--N含量分别为:101.5 mg·kg-1、28.1 mg·kg-1、2.2 mg·kg-1和25.5 mg·kg-1显著高于其他月份(P< 0.05)。其中DOC和DON含量在8月份达到最小值,分别为49.8和13.9 mg·kg-1,而NH4+-N和NO3--N含量在9月份达到最小值,分别为0.85和12.3 mg·kg-1;(2)降水的改变能够显著影响高寒草甸CO2和CH4排放通量。增加降水处理的CO2平均排放通量为460.6 ± 164.4 mg·m-2·h-1,显著高于减少降水处理(398.3 ± 141.7 mg·m-2·h-1)(P< 0.05)。增加降水处理的CH4平均吸收通量为-28.9 ± 14.1 μg·m-2·h-1, 显著小于对照(-37 ± 20.3 μg·m-2·h-1)和减少降水 (-42.9 ± 18 μg·m-2·h-1)两种处理(P< 0.05)。增加降水、对照和减少降水三种处理的N2O平均排放通量分别为10.83 ± 8.2、9.24 ± 5.9和9.67 ± 6.9 μg·m-2·h-1,三者之间差异不显著(P>0.05)。(3)不同降水强度下,CH4通量与土壤含水量相关性显著,增加降水处理下与土壤温度不显著相关,而减少降水处理与土壤5 cm和10 cm温度具有显著正相关性;增加降水处理的CO2通量和土壤含水量具有显著的负相关系,三种处理的CO2通量均与土壤5 cm和10 cm深度的温度呈正相关关系,并且与土壤DOC含量呈极显著负相关关系;增加降水和减少降水处理的N2O通量和土壤含水量均呈现出显著的正相关性,N2O通量整体上与土壤温度相关性不显著,但与土壤氮素呈显著性正相关关系;(4)生长季6月和7月份日变化观测表明,增加降水后可以显著减少高寒草甸对CH4的吸收通量,对照和增加降水处理的平均吸收量分别为-61.4和-29.9 mg·m-2·h-1;但对CO2排放通量的影响并不明显,对照和增加降水处理的平均排放量分别为190.7和188.4 mg·m-2·h-1;同时能够显著的提高N2O的平均排放通量,对照和增加降水处理的平均排放量分别为16.8和30.7 mg·m-2·h-1。

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Global climate change will include changes in the size of precipitation events, which also could affect the greenhouse gases (GHGs, CO2, CH4 and N2O) budget. GHGs emission from ecosystems can influence the global energy balance, which may often cause variations in water availability across different terrestrial landscapes.In this research, the GHGs emission flux in the eastern Qinghai-Tibetan Plateau was measured with an artificially increased precipitation and a decreased precipitation by using the static chamber meteorological chromatography method in a plant growing season (from May to September). The changes in the dissolved organic carbon (DOC), dissolved organic nitrogen (DON), ammonia (NH4+-N), and nitrate (NO3--N) concentrations in the soil were determined in the same period. The main results were:(a) The soil temperature, DOC, DON, NH4+-N and NO3--N concentrations all indicated a declining trend during the growth season. In particular, the DOC concentration rapidly reduced from May to June. The different precipitation treatments did not significantly influence the soil DOC, DON, NH4+-N and NO3--N concentrations.(b) Under both increased precipitation (IP) and decreased precipitation (DP) experimental treatments, the alpine meadow functioned as the source of CO2 and N2O and as the CH4 sink. Compared to the control check (CK), the increased precipitation slightly enhanced the average CO2 emission flux by 4.2% (P>0.05) and increased average N2O emission flux by 17.2% (P>0.05), but it declined the average CH4 absorption flux by 21.9% (P<0.05). In contrast, the decreased precipitation decreased the average CO2 emission flux by 10.2% (P<0.05), slightly enhanced the average N2O emission flux by 4.6%(P>0.05), and increased the average CH4 absorption flux by 15.9%(P<0.05).(c) The CH4 absorption fluxes of the IP and DP treatments had a significant negative regression relationship with soil moisture. The CH4 absorption fluxes also had a significant negative regression relationship with the soil temperatures at 5 cm and 10 cm-deep in the CK and DP treatments. The CO2 fluxes only had a significant negative regression relationship with soil moisture in the IP treatment. The CO2 fluxes in all three treatments had a significant positive regression relationship with the soil temperatures at 5 cm and 10 cm-deep. The N2O fluxes had a significant positive regression relationship with soil moisture in the IP and DP plots. However, the N2O fluxes did not show a significant regression relationship with the soil temperatures, and in the DP plots, the N2O flux only had a positive regression relationship with the 5 cm-deep soil temperature. The CH4 absorption fluxes had a significant positive regression relationship with the soil DOC content in the IP plot, but the CO2 fluxes had significant negative regression relationships with the soil DOC content in all three experiment plots. The N2O fluxes had significant positive regression relationships with the soil DTN and DON contents in all three experiment plots, but only had a significant positive regression relationship with the soil NH4+-N in the DP plots and with the soil NO3--N in the CK and IP plots.(d) The diurnal change (growth season in June and July) experiments showed that increased precipitation reduced the CH4 absorption value and increased N2O emission flux in the alpine meadow, but had no significantly influence on CO2 emission flux. 

Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/18984
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
谢青琰. 川西高原高寒草甸温室气体排放对降水变化的响应[D]. 北京. 中国科学院大学,2016.
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