高寒湿地温室气体释放对水位变化的响应

发布时间：2018-03-21 02:43

本文选题：青藏高原　切入点：高寒湿地　出处：《甘肃农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：在全球气候变化的背景下,温度变化和降水变化已引起青藏高原高寒湿地水位变化。青藏高原高寒草地生态系统对气候变化极其敏感,而高寒湿地生态系统是高寒草地生态系统的重要组成部分,研究高寒湿地温室气体释放与水位变化的关系,有利于深入了解草原生态系统受气候变化的影响及其对气候变化的响应,以及合理推测未来趋势,为推进国家气候变化应对行动,制定草原生态恢复的适应性管理政策提供科学依据。为了探讨水位变化对高寒湿地生态系统温室气体释放的影响,采用“中型实验生态系”的技术手段模拟全球变化中的水位降低,对青藏高原东部的若尔盖高原?红原县的高寒湿地生态系统进行研究。试验设置两个处理:自然水位WN(约土壤表面0.00 cm)和降低水位WD(自然下降至约土壤表面以下40.00cm),测定不同水位下高寒湿地生态系统CO2、CH4和N2O的释放量,并据此计算全球增温潜能(GWP),得出了以下结论:(1)水位变化对高寒湿地CO2、CH4和N2O三种温室气体释放有不同的影响:水位变化对高寒湿地CO2释放没有显著影响,WD处理和WN处理CO2累积释放量分别为23.52g·m-2和20.97g·m-2,没有显著差异,CO2释放速率与水位没有显著相关性;水位变化对高寒湿地CH4释放有显著影响,WD处理和WN处理CH4累积释放量分别为1.79g·m-2和0.86g·m-2,WD处理较WN处理减少了52.18%,CH4释放速率与水位呈极显著相关性,水位降低到一定程度,湿地会从CH4的释放源转变为CH4的吸收汇;水位变化是影响N2O释放的关键因素,WD处理和WN处理N2O累积释放量分别为6.72mg·m-2和-7.36mg·m-2,N2O释放速率与水位呈显著相关性,一定范围内的水位下降N2O释放将增加,高寒湿地水位进一步下降,N2O释放速率将减小。(2)高寒湿地生态系统CO2释放量与土壤溶解性有机碳(DOC)含量呈显著正相关关系,N2O释放量与土壤NO3--N含量呈显著正相关关系。(3)高寒湿地生态系统CO2释放量与温度有密切的关系,且降低水位提高了土壤呼吸对温度的敏感度;高寒湿地CH4释放受土壤温度影响显著,且降低水位提高了CH4释放量与温度的拟合度;高寒湿地生态系统N2O通量较小,且影响因素较多,温度对N2O通量的影响效果被其他影响因素掩盖,没有发现温度与高寒湿地生态系统N2O释放量之间存在明显的相关性。(4)同一时间尺度上,WD处理的GWP显著低于WN处理,说明高寒湿地水位降低有利于减弱温室气体的全球增温潜能。
[Abstract]:Under the background of global climate change, the changes of temperature and precipitation have caused the changes of water level of alpine wetlands on the Qinghai-Xizang Plateau, and the alpine grassland ecosystem of the Tibetan Plateau is extremely sensitive to climate change. The alpine wetland ecosystem is an important part of alpine grassland ecosystem. The relationship between greenhouse gas release and water level change in alpine wetland is studied. Contributing to an in-depth understanding of the effects of climate change on grassland ecosystems and their response to climate change, as well as reasonable projections of future trends, in order to advance national climate change responses, In order to study the effect of water level change on greenhouse gas release from alpine wetland ecosystem, The "medium Experimental ecosystem" is used to simulate the global change in the water level, the eastern part of the Qinghai-Xizang Plateau in the Zoige Plateau? Study on alpine wetland ecosystem in Hongyuan county. Two treatments were set up: natural water level WN (about 0. 00cm soil surface) and low water level WD (natural drop below about 40. 00cm) to determine alpine wetland ecology under different water levels. The emission of CO _ 2H _ 4 and N _ 2O from the system, Based on this, the global warming potential (GWPN) is calculated, and the following conclusions are drawn: the variation of water level has different effects on the release of three greenhouse gases, CO _ 2N _ 2 Ch _ 4 and N _ 2O in alpine wetland: the change of water level has no significant effect on CO2 release from alpine wetland and WN. The cumulative release of CO2 was 23.52 g 路m ~ (-2) and 20.97 g 路m ~ (-2), respectively. There was no significant difference between CO _ 2 release rate and water level. The water level change had significant influence on the CH4 release from alpine wetland. The cumulative release of CH4 in WD treatment and WN treatment were 1.79 g 路m -2 and 0.86 g 路m -2, respectively. Compared with WN treatment, the release rate of CH4 decreased by 52.18g 路m ~ (-2), and the water level decreased to a certain extent. The water level change is the key factor affecting the N2O release. The cumulative N2O emission of WD and WN treatments are 6.72 mg 路m ~ (-2) and -7.36 mg 路m ~ (-2) N _ 2O, respectively. There is a significant correlation between the water level and the water level. Within a certain range of water levels falling, N2O emissions will increase, The release rate of N2O in alpine wetland will be decreased further. 2) there is a significant positive correlation between the amount of CO2 released from alpine wetland ecosystem and the content of dissolved organic carbon (DOC) in soil. There is a significant positive correlation between the release of N2O and the content of NO3--N in soil. (3) the amount of CO2 released from alpine wetland ecosystem is closely related to temperature. Lowering water level increased the sensitivity of soil respiration to temperature, CH4 release from alpine wetland was significantly affected by soil temperature, and decreased water level increased the fit between CH4 emission and temperature, and N2O flux in alpine wetland ecosystem was small. The effect of temperature on N2O flux was masked by other factors. There was no obvious correlation between temperature and N2O emission from alpine wetland ecosystem. 4) the GWP of WWD treatment was significantly lower than that of WN treatment on the same time scale, which indicated that the decrease of water level in alpine wetland was beneficial to reduce the global warming potential of greenhouse gas.
【学位授予单位】：甘肃农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X171

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