發(fā)布時(shí)間：2018-04-28 00:25

  本文選題：黃土丘陵區(qū) + 草地�。� 參考：《西北農(nóng)林科技大學(xué)》2017年碩士論文

【摘要】：草地是陸地生態(tài)系統(tǒng)的重要組成部分,因此加強(qiáng)對(duì)草地生態(tài)系統(tǒng)的研究對(duì)于維護(hù)我國西北地區(qū)生態(tài)平衡,加強(qiáng)區(qū)域水土流失治理甚至對(duì)進(jìn)一步理清全球碳收支情況都具有重要的現(xiàn)實(shí)意義。本研究以陜北黃土丘陵區(qū)的茵陳蒿-鐵桿蒿草地生態(tài)系統(tǒng)為研究對(duì)象,在2012-2014年間基于渦度相關(guān)法對(duì)該草地的碳通量(NEP,凈生態(tài)系統(tǒng)生產(chǎn)力;GEP,總生態(tài)系統(tǒng)生產(chǎn)力;RE,生態(tài)系統(tǒng)呼吸)進(jìn)行觀測(cè),通過數(shù)據(jù)處理、質(zhì)量控制等過程獲得可靠的碳通量數(shù)據(jù),完成了對(duì)該草地碳通量在時(shí)間尺度變化特征的研究,并分析了其影響因素。另外,通過收集已發(fā)表的基于渦度相關(guān)法研究的文章,共篩選出包括本文研究站點(diǎn)在內(nèi)的15個(gè)中國草地站點(diǎn),分析中國草地碳通量空間變化特征,并初步探明影響其變化的因素。得出主要結(jié)論如下:(1)所測(cè)定的茵陳蒿-鐵桿蒿草地生態(tài)系統(tǒng)在2012-2014年均表現(xiàn)為碳匯,NEP呈現(xiàn)出在生長季出現(xiàn)最大值而春、冬季出現(xiàn)最低值的季節(jié)性變化特征,全年NEP分別為250.33 g Cm-2yr-1、339.94 g Cm-2yr-1、318.99 g Cm-2yr-1,其固碳能力高于我國溫帶典型草地。(2)三年全年GEP分別為433.2 g Cm-2yr-1、476.1 g Cm-2yr-1、453.7 g Cm-2yr-1,碳吸收能力較為一致(CV=4%),呈現(xiàn)季節(jié)性變化規(guī)律。全年RE分別為182.9 g Cm-2yr-1、136.2 g Cm-2yr-1、134.7 g Cm-2yr-1,月尺度的RE除生長旺期較大外,在生長初期和末期的呼吸強(qiáng)度相似,各月差異較小。(3)對(duì)單獨(dú)因素分析,日尺度NEP、GEP變化的影響因素主要為空氣溫度(Ta),日尺度RE的影響因素不明晰。NEP、GEP和RE在月尺度的影響因素最主要的是增強(qiáng)型植被指數(shù)(EVI),其次依次為空氣溫度(Ta)、降水量(P)和凈輻射(Rn)等。(4)在多因素共同作用下,日尺度NEP、GEP主要受到Rn、Ta、飽和水汽壓差(VPD)的影響,月尺度NEP受到Ta、EVI的影響,月尺度GEP受到Ta、VPD、EVI的影響。日尺度RE受到Ta和VPD的影響,月尺度RE只受到EVI的影響。Ta可以增強(qiáng)Rn對(duì)碳通量的影響作用,EVI也可以增強(qiáng)Ta的影響作用,而VPD則會(huì)減弱Rn和Ta的影響作用。(5)季節(jié)性干旱會(huì)導(dǎo)致草地NEP、GEP下降,RE受到的影響并不明顯。在干旱脅迫期NEP、GEP的影響因素主要為Ta和土壤含水量(SWC)。(6)中國草地生態(tài)系統(tǒng)的NEP、GEP、RE存在空間變化特征,與緯度呈現(xiàn)二次函數(shù)關(guān)系,當(dāng)緯度達(dá)到36-37°N時(shí),NEP、GEP、RE均為最高。(7)年均降水量(MAP)、年均溫(MAT)、EVI為影響碳通量空間變化的重要因素,其中MAP與GEP、RE為二次函數(shù)關(guān)系,與NEP關(guān)系不顯著;MAT與NEP、RE為線性關(guān)系,與GEP關(guān)系不顯著;EVI與NEP、GEP、RE均為線性關(guān)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 擄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.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：S812

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