陕北黄土丘陵区草地生态系统碳通量及其影响因素研究

发布时间：2018-04-28 00:25

本文选题：黄土丘陵区 + 草地　；参考：《西北农林科技大学》2017年硕士论文

【摘要】：草地是陆地生态系统的重要组成部分,因此加强对草地生态系统的研究对于维护我国西北地区生态平衡,加强区域水土流失治理甚至对进一步理清全球碳收支情况都具有重要的现实意义。本研究以陕北黄土丘陵区的茵陈蒿-铁杆蒿草地生态系统为研究对象,在2012-2014年间基于涡度相关法对该草地的碳通量(NEP,净生态系统生产力;GEP,总生态系统生产力;RE,生态系统呼吸)进行观测,通过数据处理、质量控制等过程获得可靠的碳通量数据,完成了对该草地碳通量在时间尺度变化特征的研究,并分析了其影响因素。另外,通过收集已发表的基于涡度相关法研究的文章,共筛选出包括本文研究站点在内的15个中国草地站点,分析中国草地碳通量空间变化特征,并初步探明影响其变化的因素。得出主要结论如下:(1)所测定的茵陈蒿-铁杆蒿草地生态系统在2012-2014年均表现为碳汇,NEP呈现出在生长季出现最大值而春、冬季出现最低值的季节性变化特征,全年NEP分别为250.33 g Cm-2yr-1、339.94 g Cm-2yr-1、318.99 g Cm-2yr-1,其固碳能力高于我国温带典型草地。(2)三年全年GEP分别为433.2 g Cm-2yr-1、476.1 g Cm-2yr-1、453.7 g Cm-2yr-1,碳吸收能力较为一致(CV=4%),呈现季节性变化规律。全年RE分别为182.9 g Cm-2yr-1、136.2 g Cm-2yr-1、134.7 g Cm-2yr-1,月尺度的RE除生长旺期较大外,在生长初期和末期的呼吸强度相似,各月差异较小。(3)对单独因素分析,日尺度NEP、GEP变化的影响因素主要为空气温度(Ta),日尺度RE的影响因素不明晰。NEP、GEP和RE在月尺度的影响因素最主要的是增强型植被指数(EVI),其次依次为空气温度(Ta)、降水量(P)和净辐射(Rn)等。(4)在多因素共同作用下,日尺度NEP、GEP主要受到Rn、Ta、饱和水汽压差(VPD)的影响,月尺度NEP受到Ta、EVI的影响,月尺度GEP受到Ta、VPD、EVI的影响。日尺度RE受到Ta和VPD的影响,月尺度RE只受到EVI的影响。Ta可以增强Rn对碳通量的影响作用,EVI也可以增强Ta的影响作用,而VPD则会减弱Rn和Ta的影响作用。(5)季节性干旱会导致草地NEP、GEP下降,RE受到的影响并不明显。在干旱胁迫期NEP、GEP的影响因素主要为Ta和土壤含水量(SWC)。(6)中国草地生态系统的NEP、GEP、RE存在空间变化特征,与纬度呈现二次函数关系,当纬度达到36-37°N时,NEP、GEP、RE均为最高。(7)年均降水量(MAP)、年均温(MAT)、EVI为影响碳通量空间变化的重要因素,其中MAP与GEP、RE为二次函数关系,与NEP关系不显著;MAT与NEP、RE为线性关系,与GEP关系不显著;EVI与NEP、GEP、RE均为线性关系。
[Abstract]:Grassland is an important part of terrestrial ecosystem, so strengthening the study of grassland ecosystem can maintain the ecological balance in Northwest China. It is of great practical significance to strengthen regional soil and water loss management even to further clarify the global carbon budget. In this study, the ecosystem of Artemisia capillaris and Artemisia artemisia in the loess hilly region of northern Shaanxi was taken as the research object. Carbon fluxes (NEP, net ecosystem productivity, total ecosystem productivity, ecosystem respiration) of the grassland were observed in 2012-2014 based on vorticity correlation method, and reliable carbon flux data were obtained through data processing, quality control and other processes. The change characteristics of carbon flux in time scale were studied and the influencing factors were analyzed. In addition, through collecting the published articles based on vorticity correlation method, 15 grassland sites in China, including the research sites in this paper, were selected to analyze the spatial variation characteristics of grassland carbon flux in China. The factors that influence its change are preliminarily investigated. The main conclusions are as follows: (1) the ecosystem of Artemisia capillaris and Artemisia tenuifolia showed a seasonal variation of the maximum value in growth season and the lowest value in winter, and the annual average value of NEP in 2012-2014 was the highest in growth season and the lowest in winter. The annual NEP was 250.33 g Cm-2yr-1339.94 g Cm-2yr-1318.99 g Cm-2yr-1, and its carbon sequestration capacity was higher than that of typical grassland in temperate zone of China. The annual GEP was 433.2 g Cm-2yr-1476.1 g Cm-2yr-1453.7 g Cm-2yr-1 for three years. The annual RE was 182.9 g Cm-2yr-1136.2 g Cm-2yr-1134.7 g Cm-2yr-1. The respiration intensity in the early and late growth stage was similar, and the difference was small in each month. The main influencing factors of daily scale NEP GEP are air temperature, the influence factors of diurnal RE are unclear. The most important influencing factors of daily scale RE are enhanced vegetation index (EVII), followed by air temperature and precipitation (P). And net radiation (Rn), et al. 4) under the combined action of many factors, The diurnal scale NEP is mainly influenced by RN Ta, saturated water vapor pressure difference (VPDs), the monthly scale NEP is influenced by Taw EVI, and the monthly scale GEP is influenced by Tahwe VPD-EVI. Day scale RE is affected by Ta and VPD, and monthly scale RE is affected only by EVI. Ta can enhance the effect of rn on carbon flux. However, VPD could weaken the effects of rn and Ta. The main influencing factors of NEPN GEP during drought stress were Ta and soil water content (SWCN. 6) there were spatial variation characteristics of NEPGE-GEPN RE in grassland ecosystem of China, and there was a quadratic function relationship between NEPGE-GEP and latitude. When latitude reaches 36-37 掳N, the average annual precipitation is the highest. The annual mean temperature is an important factor affecting the spatial change of carbon flux. The relationship between MAP and GEPN RE is quadratic function, and the relationship with NEP is not linear. There was no significant linear relationship between GEP and RE.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S812

【参考文献】