模拟增温和围栏封育对青海湖北岸高寒草甸化草原生态系统碳交换影响

发布时间：2018-04-29 17:28

本文选题：模拟增温 + 围栏封育　；参考：《中国科学院研究生院(地球环境研究所)》2015年博士论文

【摘要】：碳循环是生物地球化学循环中主要的组成部分之一,是一个生命关键元素从外部环境进入到生物体再最终返回到外部环境中的过程。陆地生态系统碳循环不仅受到全球气候变化和人类活动的影响,同时,陆地生态系统碳循环也反馈于气候变化和人类活动。这一过程为地球上的生命体提供了物质循环与能量流动的驱动力,很多生命关键要素都参与其中。研究生态系统碳循环每个组分对全球变化是如何响应的,对我们更准确的理解碳循环与气候变化间的反馈有重要的意义。然而我们目前对生态系统碳循环对外界干扰的响应的理解还相对比较薄弱。我们采用了国际冻原计划所指定的开顶箱模拟增温实验(OTC)研究了青海湖北岸高寒草甸化草原生态系统碳循环对模拟增温的响应。同时我们也观测了生态系统碳循环过程对自由放牧和围栏封育的响应。OTC模拟增温显著地增加了土壤温度,但却降低了土壤湿度。三年的野外控制实验的结果表明,OTC模拟增温样地的土壤温度平均比对照样地的土壤温度高1.03 oC,而OTC模拟增温样地的土壤湿度要比对照样地的土壤湿度低3.7%。同时,模拟增温也显著地增加了地上生物量和地下生物量,与对照样地相比三年的模拟增温实验平均增加了地上生物量的17.4%,也平均增加了地下生物量的24.3%。模拟增温还显著地改变了群落的物种组成,与对照样地相比,模拟增温显著地增加了禾草科、豆科、和莎草科物种的重要性,但是降低了杂草科物种的重要性。各物种的生物量累积也发生了变化,与对照样地相比模拟增温分别增加了禾草科、豆科、和莎草科地上生物量的12.9%,27.6%,和21.5%,但对杂草地上生物量没有影响。土壤呼吸和生态系统呼吸对我们实验中的的增温(约1度)响应不显著。但是土壤呼吸和生态系统呼吸的组分对模拟增温有显著的响应。我们三年的野外观测表明,与对照样地相比,模拟增温显著地增加了地上植物呼吸的28.7%,和总植物呼吸的19.9%;与此相反,模拟增温降低了土壤异养呼吸的10.4%。模拟增温对地下植物呼吸没有显著地影响。同时,模拟增温也改变了不同生态系统呼吸组分对生态系统呼吸的贡献。与对照样地相比,模拟增温增加了地上植物呼吸和总植物呼吸对生态系统呼吸贡献的17.3%和8.4%;但是模拟增温降低了土壤呼吸和土壤异养呼吸对生态系统呼吸贡献的10.8%和19.0%。多元回归分析表明,土壤湿度在不同生态呼吸组分中都起着重要的作用,这表明土壤呼吸和生态系统呼吸对模拟增温的不敏感性可能和模拟增温导致的水分降低有关。另外模拟增温引起的地上植物呼吸和总植物呼吸与增温引起的地上生物量的增加显著相关,而模拟增温引起的土壤异养呼吸的降低和增温引起的微生物碳含量的降低显著相关。模拟增温分别增加了净生态系统碳交换和总生态系统碳交换的31.0%和18.7%。otc模拟增温引起的土壤温度和土壤湿度的改变不足以解释模拟增温引起的生态系统碳交换过程。然而,模拟增温引起的生态系统碳交换过程和模拟增温引起的植物功能群落的改变是密切相关的。我们的研究表明,otc模拟增温引起的群落结构的改变会明显的改变生态系统碳交换过程。与自由放牧样地相比,围栏封育显著地增加了土壤湿度的但降低了土壤温度。同时,与自由放牧样地相比,围栏封育也增加了地上生物量的40.5%,降低了土壤微生物碳含量,但对地下生物量没有影响。围栏封育显著地降低了土壤呼吸的23.35%,但围栏封育增加了净生态系统碳交换的47.37%,生态系统呼吸的36.55%,和总生态系统碳交换的33.14%。多元线性回归表明,围栏封育引起的土壤呼吸的降低和围栏封育引起的土壤温度和湿度的变化,以及围栏封育引起的土壤微生物碳的降低显著相关。围栏封育引起的净生态系统碳交换、生态系统呼吸、和总生态系统碳交换和围栏封育引起的生物量的变化显著相关。我们的研究表明围栏封育是一个有效的生态系统固碳方式。模拟增温显著地降低了土壤呼吸和生态系统呼吸的温度敏感性。我们的研究表明,模拟增温和生态系统碳循环间的正反馈作用可能没有我们之前预测的那么强烈。然而围栏封育增加了土壤呼吸和生态系统呼吸的温度敏感性,我们的研究表明尽管围栏封育是一种有效的生态系统固碳方式,然而围栏封育样地所固定碳在将来全球变暖的背景下更容易被分解。我们的研究结果表明模拟增温和围栏封育都会显著地影响到生态系统碳循环,当我们考虑到生态系统碳循环的过程的时候需要把这些因素引起的生态系统碳交换的变化考虑在内。同时,模拟增温和围栏封育间可能有一些交互作用,我们以后的研究应更多的关注于他们的交互作用。
[Abstract]:Carbon cycle is one of the main components of the biogeochemical cycle. It is a process that a vital element of life enters from the external environment to the organism and then returns to the external environment. The carbon cycle of the terrestrial ecosystem is not only affected by the global climate change and human activity, but also the carbon cycle of the terrestrial ecosystem. Climate change and human activity. This process provides the life body on the earth with the driving force of material circulation and energy flow, and many key elements of life are involved. It is important to study how each component of the carbon cycle responds to the global change, and it is important for us to more accurately understand the feedback between carbon cycle and climate change. However, we are still relatively weak in understanding the response of the ecosystem carbon cycle to external disturbances. We used the open top box simulated temperature increase experiment (OTC) designated by the international tundra program to study the response of the carbon cycle of the alpine meadow ecosystem on the North Bank of the Qinghai Lake to the simulated temperature increase. The response of the ecosystem carbon cycle to the response to free grazing and enclosure closure significantly increased the soil temperature, but decreased the soil moisture. The results of the field control experiments in three years showed that the soil temperature of the OTC simulated temperature increasing sample was 1.03 oC higher than that of the same soil, and the soil temperature of the simulated temperature increasing sample was three. The soil moisture content is lower than the soil moisture 3.7%., and the simulated temperature increase also significantly increases the aboveground biomass and the subsurface biomass. Compared with the control sample, the simulated temperature increase experiment in three years increases 17.4% of the aboveground biomass, and the average increase of the 24.3%. simulated temperature of the underground biomass also significantly changes the community. Compared with the control plots, the simulated temperature increase significantly increased the importance of the grasses, legumes, and the sedge species, but reduced the importance of the weeds species. The biomass accumulation of each species also changed. Compared with the control plots, the simulated warming was added to 12.9% of the grasses, legumes, and the sedge. 27.6%, and 21.5%, but had no effect on the aboveground biomass. Soil respiration and ecosystem respiration did not respond significantly to the temperature increase (about 1 degrees) in our experiments. But soil respiration and ecosystem respiration had a significant response to simulated temperature increase. Our three year field survey showed that the simulated temperature increased significantly compared with the control sample. At the same time, 28.7% of the plant respiration and 19.9% of the total plant respiration were increased. On the contrary, the simulated temperature increase reduced the 10.4%. simulated temperature increase of soil heterotrophic respiration not significantly affecting the respiration of the plant. Meanwhile, the simulated temperature increase also changed the contribution of different ecosystem respiration components to the ecosystem respiration. Simulated warming increased the contribution of plant respiration and total plant respiration to ecosystem respiration by 17.3% and 8.4%, but the 10.8% and 19.0%. multivariate regression analysis of soil respiration and soil heterotrophic respiration to ecosystem respiration showed that soil humidity played an important role in different ecologic respiratory components. It is indicated that the insensitivity of soil respiration and ecosystem respiration to simulated temperature increase may be related to the water reduction caused by simulated temperature increasing. In addition, the increase of aboveground biomass caused by plant respiration and total plant respiration is significantly related to the increase of aboveground biomass caused by simulated temperature increasing, and the decrease of soil heterotrophic respiration and increasing temperature induced by simulated temperature increase. The reduction of carbon exchange in the net ecosystem and the carbon exchange of the total ecosystem, respectively, increased the soil temperature and soil moisture content caused by the 31% and 18.7%.otc simulation increases in the net ecosystem. The system carbon exchange process is closely related to the change of plant functional community caused by simulated temperature increasing. Our study shows that the changes in the community structure caused by the OTC simulated temperature increase will obviously change the carbon exchange process of the ecosystem. The soil moisture content is significantly increased but the soil temperature is reduced significantly compared with the free grazing plots. At the same time, compared with the free grazing land, the enclosure was also increased by 40.5% of the aboveground biomass, reducing the soil microbial carbon content, but having no effect on the soil biomass. The enclosure closure significantly reduced the soil respiration by 23.35%, but the enclosure was increased by 47.37% of the net ecosystem carbon exchange, 36.55% of the ecosystem respiration. 33.14%. multiple linear regression of the ecosystem carbon exchange showed that the decrease of soil respiration caused by enclosure and the change of soil temperature and humidity caused by enclosure closure, as well as the decrease of soil microbial carbon caused by enclosure closure were significant. The net ecosystem carbon exchange, ecosystem respiration, and total ecology caused by enclosure closure were caused by enclosure closure. Our study shows that enclosure closure is an effective ecosystem carbon fixation method. The simulated temperature increase significantly reduces the temperature sensitivity of soil respiration and ecosystem respiration. Our study shows that the model increases the positive and negative effects of the carbon cycle in the ecosystem. Feeding may not be as strong as we had previously predicted. However, fence closure increases the temperature sensitivity of soil respiration and ecosystem respiration. Our study shows that although enclosure is an effective ecosystem carbon fixation, the fixed carbon in enclosure is more likely to be more vulnerable to future global warming. Our results show that both simulated warming and fence closure have a significant impact on the ecosystem carbon cycle. When we consider the carbon cycle of the ecosystem, we need to take into account the changes in the carbon exchange caused by these factors. We should pay more attention to their interaction in future research.

【学位授予单位】：中国科学院研究生院(地球环境研究所)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：S812

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