锡林郭勒半干旱草原生长季呼吸作用与碳交换研究

发布时间：2018-05-28 04:41

本文选题：半干旱草原 + 碳交换　；参考：《南京信息工程大学》2017年硕士论文

【摘要】：本文利用锡林浩特国家气候观象台的涡度相关湍流资料、土壤温湿度数据以及MODIS遥感数据,分析了 2010～2012年锡林郭勒半干旱针茅草原生态系统的呼吸过程及关键气候影响因子,比较了 4种不同的生态系统呼吸模型在该生态系统的适用性及敏感性系数,在此基础上讨论了该生态系统生长季的净碳交换(NEE)、呼吸作用(Reco)以及总初级生产力(GPP)的年际变化特征,最后验证了运用增强植被指数(EVI)反演GPP的可靠性,并将其作为生物因子引入以改进现有的呼吸模型。研究得到以下主要结论:(1)该半干旱区针茅草原生态系统的呼吸作用主要受到土壤温度和土壤含水量的共同影响,其中土壤含水量是生态系统呼吸的重要限制因子。2010年和2011年生长季降水量偏少,呼吸速率表现出与土壤含水量相近的变化趋势,土壤含水量的对其影响可分为三个区间来讨论(12%、12%～20%和20%); 2012年降水充沛,呼吸速率与土壤温度的变化趋势更为相关,且未出现随土壤含水量的增加呼吸速率的变化趋势出现分段的情况。(2)呼吸模型模拟结果及敏感性分析表明Q10模型表现优于其他三种连乘模型,能够解释锡林郭勒半干旱呼吸作用的64% (R2=0.64)。Q10模型因为其函数结构的优越性和在高温高湿度时对温度敏感,低温高湿时对含水量不敏感的特性,优于其他三种连乘形式的呼吸模型。但基于土壤温度和土壤含水量的呼吸模型无法反应植被生长状况对植被自养呼吸的影响,因此其对生态系统总呼吸的模拟能力存在一定局限。(3)使用Q10模型模拟的三年生长季的生态系统呼吸累积总量分别为157.32g C·m-2、138.75g gC·m-2 和 246.32g C·m—2。总初级生产力(GPP)累计总量分别为267.52 g C·m_2、207.57 g C·m—2和555.85 g C·m_2,净碳交换速率分别为-110.28 g C·m-2, -68.79 g C·m-2, -310.05 g C·m_2,该草原生态系统在这三年生长季中均表现出较为显著的碳汇功能。2010～2012年生长季中,土壤含水量的年际变化是影响该生态系统碳交换的重要环境因子,干旱胁迫对光合作用的影响大于呼吸作用。(4)增强植被指数EVI可以较好地反映地表植被生长状况,引入EVI指数作为生物因子对呼吸模型改进后,连乘形式的呼吸模型和Q10模型的模拟结果均有显著提升(R2提高约0.10),说明在呼吸模型中引入基于遥感数据的生物因子在区域尺度的呼吸过程碳交换评估中具有较好的应用价值。
[Abstract]:Based on the vorticity related turbulence data, soil temperature and humidity data and MODIS remote sensing data of the National Climate Observatory in Xilinhaote, this paper analyzed the respiration process and the key climatic factors of Cylingol semi-arid Stipa steppe ecosystem from 2010 to 2012. The applicability and sensitivity coefficient of four different ecosystem respiration models in the ecosystem were compared. On this basis, the interannual variation characteristics of net carbon exchange (GPP), respiration and total primary productivity (GPP) in the growing season of the ecosystem are discussed. Finally, the reliability of using enhanced vegetation index (EVI) to retrieve GPP is verified. It is introduced as a biological factor to improve the existing respiratory model. The main conclusions of the study are as follows: (1) the respiration of Stipa chinensis grassland ecosystem in this semi-arid area is mainly affected by soil temperature and soil water content. Soil water content is an important limiting factor for ecosystem respiration. The precipitation in 2010 and 2011 growth seasons is relatively small, and the respiration rate shows a trend similar to that of soil water content. The effect of soil water content on soil water content can be divided into three sections to discuss 20% and 20% of soil moisture content. In 2012, the precipitation was abundant, and the respiration rate was more related to the change trend of soil temperature. And there was no segmentation of respiration rate with the increase of soil moisture content. The simulation results and sensitivity analysis of Q10 model showed that Q10 model was superior to the other three continuous multiplication models. The Q10 model, which can explain the semiarid respiration of Xilinguole, is superior to the other three multiple respiration models because of its superiority in function structure and its sensitivity to temperature at high temperature and humidity, and insensitivity to water content at low temperature and high humidity. However, the respiration model based on soil temperature and soil moisture could not reflect the effect of vegetation growth on autotrophic respiration. Therefore, its ability to simulate the total respiration of ecosystem is limited to some extent.) the cumulative total respiration of ecosystem in the three years growing season simulated by Q10 model is 157.32 g C m-2138.75 g GC m -2 and 246.32 g C m -2, respectively. The accumulative total amount of total primary productivity is 267.52 g C m m -2 and 555.85 g C m 2 respectively. The net carbon exchange rate is -110.28 g C m -2, -68.79 g C m -2, -310.05 g C m 2, respectively. During the growing season from 2010 to 2012, The interannual variation of soil water content is an important environmental factor affecting carbon exchange in the ecosystem. Drought stress has more effect on photosynthesis than respiration. The enhanced vegetation index (EVI) can better reflect the growth of surface vegetation. After introducing EVI index as a biological factor to improve the respiratory model, The simulation results of even multiplicative respiration model and Q10 model have significantly improved R2 by about 0.10, which indicates that the introduction of biological factors based on remote sensing data into the respiratory model has a good application value in the assessment of carbon exchange during respiration at regional scale.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S812

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