本文選題：光化學(xué)反射指數(shù) + 光能利用率��； 參考：《南京大學(xué)》2016年博士論文

【摘要】：植物的光合作用是獲取太陽(yáng)能并轉(zhuǎn)化為化學(xué)能的重要進(jìn)程。通過(guò)光合作用,陸地生態(tài)系統(tǒng)的總初級(jí)生產(chǎn)力成為全球陸地碳通量最大的組成部分,且表現(xiàn)出顯著的時(shí)空變化。遙感技術(shù)具有較廣的空間覆蓋能力,結(jié)合光能利用率模型,有助于提升估算總初級(jí)生產(chǎn)力的能力。一旦獲得準(zhǔn)確的植被冠層吸收的光合有效輻射,光能利用率就成為估算總初級(jí)生產(chǎn)力的關(guān)鍵參數(shù)。光能利用率的變化由眾多限制光合作用進(jìn)程的因素決定,準(zhǔn)確估算光能利用率對(duì)于利用遙感數(shù)據(jù)和光能利用率模型估算區(qū)域和全球尺度的總初級(jí)生產(chǎn)力起到至關(guān)重要的作用。一種有效的方法是利用遙感手段獲得的光化學(xué)反射指數(shù)(PRI=(R531-R570)/(R531 + R570),R531和R570分別為531和570m處的反射率)。但是,冠層尺度光化學(xué)反射指數(shù)的應(yīng)用受到很多非生理因素的影響。為了拓展光化學(xué)反射指數(shù)在監(jiān)測(cè)光合作用特征研究中的應(yīng)用,需要系統(tǒng)地考慮這些因素的影響。本研究針對(duì)影響冠層尺度光化學(xué)反射指數(shù)應(yīng)用的主要因素,包括以下研究?jī)?nèi)容：1)建立自動(dòng)的多角度高光譜觀測(cè)系統(tǒng),以獲取連續(xù)的冠層多角度光化學(xué)反射指數(shù)數(shù)據(jù)；2)利用生長(zhǎng)季內(nèi)多角度觀測(cè)數(shù)據(jù),計(jì)算冠層尺度光化學(xué)反射指數(shù)的算術(shù)平均值,評(píng)估光化學(xué)反射指數(shù)監(jiān)測(cè)光能利用率變化的能力,并分析影響光化學(xué)反射指數(shù)與光能利用率相關(guān)關(guān)系的外部(非生理)因素：3)區(qū)分陰葉和陽(yáng)葉,結(jié)合四尺度幾何光學(xué)模型,構(gòu)建兩葉光化學(xué)反射指數(shù)算法；4)評(píng)估兩葉光化學(xué)反射指數(shù)算法對(duì)提升光化學(xué)反射指數(shù)監(jiān)測(cè)光能利用率能力的效果,以及減少外部因素對(duì)光化學(xué)反射指數(shù)影響的效果。研究的主要內(nèi)容和結(jié)論歸納如下：1)本研究于2013年1月在江西省千煙洲生態(tài)網(wǎng)絡(luò)實(shí)驗(yàn)站通量塔上安裝了一套改進(jìn)的冠層自動(dòng)多角度高光譜觀測(cè)系統(tǒng)。在每15分鐘一個(gè)循環(huán)的觀測(cè)中,可獲得用于計(jì)算光化學(xué)反射指數(shù)的多角度光譜數(shù)據(jù),觀測(cè)天頂角為(37°,47°,57。)或(42°,52°,62。)及瞬時(shí)的太陽(yáng)天頂角,觀測(cè)方位角范圍是45。至325。(以北為原點(diǎn))。獲得的光譜數(shù)據(jù)經(jīng)白板校正和暗電流校正等預(yù)處理后,可用于計(jì)算冠層反射率和光化學(xué)反射指數(shù)。選取觀測(cè)天頂角小于63。的所有不同角度的光化學(xué)反射指數(shù),通過(guò)算術(shù)平均法求得冠層尺度每半小時(shí)的光化學(xué)反射指數(shù)；2)在亞熱帶針葉林,半小時(shí)的光化學(xué)反射指數(shù)和光能利用率均表現(xiàn)出明顯的日變化和季節(jié)變化,并隨著飽和水汽壓差、氣溫和光合有效輻射的增加而增加�？偟膩�(lái)說(shuō),光化學(xué)反射指數(shù)能夠捕捉到光能利用率的日變化和季節(jié)變化。然而,光化學(xué)反射指數(shù)與光能利用率的相關(guān)關(guān)系在整個(gè)生長(zhǎng)季中變化劇烈。最顯著的相關(guān)關(guān)系(R2=0.6427,p0.001)發(fā)生在7月份,最差的關(guān)系發(fā)生在5月份。整個(gè)生長(zhǎng)季中,光化學(xué)反射指數(shù)在晴朗或多云(晴空指數(shù)CI0.3)、飽和水汽壓差適中或較高(20 hPa)且溫度也較高(31℃)的情況下與光能利用率更為相關(guān)�？傊�,光化學(xué)反射指數(shù)對(duì)探測(cè)脅迫狀態(tài)下的光能利用率的變化具有較好的敏感性,且敏感性隨著環(huán)境的改善,即空氣水汽壓、溫度和土壤濕度條件良好的情況下而降低；3)為提高方向性光化學(xué)反射指數(shù)監(jiān)測(cè)光能利用率變化的能力,冠層被視為兩片大葉,即陽(yáng)葉和陰葉。以四尺度幾何光學(xué)模型為基礎(chǔ),各觀測(cè)角度的冠層反射可被分解為光照和陰影葉片及光照和陰影背景四部分。為了估算這四部分各自所占的比例,三種理論基礎(chǔ)不同的模型用來(lái)估算陽(yáng)葉比例并進(jìn)行了對(duì)比。最終,冠層反射率與葉片反射率的比值作為陽(yáng)葉比例,而陰葉比例通過(guò)四尺度幾何光學(xué)模型計(jì)算。進(jìn)而,陰葉和陽(yáng)葉的光化學(xué)反射指數(shù)可利用每15分鐘的多角度觀測(cè)數(shù)據(jù)通過(guò)最小二乘法擬合得到。根據(jù)陰葉和陽(yáng)葉的比例,以及陰葉和陽(yáng)葉的光化學(xué)反射指數(shù)反算得到模擬的光化學(xué)反射指數(shù),可以有效的捕捉到每15分鐘觀測(cè)周期內(nèi)不同角度觀測(cè)到的光化學(xué)反射指數(shù)的變化(70%,p0.05,n=5700);4)無(wú)論在半小時(shí)或日尺度,和通過(guò)一定時(shí)間段內(nèi)多角度觀測(cè)算術(shù)平均計(jì)算得到的冠層大葉光化學(xué)反射指數(shù)相比,區(qū)分陰陽(yáng)葉后計(jì)算的兩葉光化學(xué)反射指數(shù)與通量觀測(cè)得到的光能利用率的相關(guān)關(guān)系都得到了顯著提升(60%)。在7至9月份的干季,日平均的兩葉光化學(xué)反射指數(shù)與光能利用率的相關(guān)性顯著高于大葉光化學(xué)反射指數(shù)與其的相關(guān)性。最顯著的相關(guān)關(guān)系發(fā)生在7月(R2=0.785,p0.001)。在半小時(shí)尺度,兩葉光化學(xué)反射指數(shù)探測(cè)低到中度干旱脅迫影響光能利用率的能力顯著,但不能有效探測(cè)嚴(yán)重的大氣干旱和高溫脅迫。這可能是由于植物遭受嚴(yán)重脅迫時(shí),其他方式如光呼吸耗散光合作用無(wú)法固定的能量的比例增加,而冠層光化學(xué)反射指數(shù)無(wú)法探測(cè)到這種變化�？傮w來(lái)說(shuō),兩葉算法有效降低了一些非生理因素,如太陽(yáng)觀測(cè)幾何對(duì)光化學(xué)反射指數(shù)造成的外在干擾。
[Abstract]:The photosynthesis of plants is an important process for obtaining solar energy and converting into chemical energy . Through photosynthesis , the total primary productivity of terrestrial ecosystems becomes the largest component of global terrestrial carbon flux , and shows significant spatial and temporal changes . In order to expand the application of light - chemical reflectance index in monitoring photosynthesis characteristics , the influence of these factors should be considered systematically in order to expand the application of light - chemical reflectance index in monitoring photosynthesis characteristics .
2 ) using multi - angle observation data in the growing season , calculating the arithmetic mean value of the optical chemical reflection index of the crown layer , evaluating the light energy utilization rate variation ability of the light chemical reflection index , and analyzing the external ( non - physiological ) factors influencing the relationship between the light chemical reflection index and the light energy utilization rate : 3 ) differentiating the female and male leaves , combining the four - scale geometric optical model , and constructing the two - leaf photochemical reflection index algorithm ;
4 ) To evaluate the effect of the two - leaf photochemical reflection index algorithm on the light energy utilization rate and to reduce the effect of external factors on the photochemical reflection index . The main contents and conclusions of the study are summarized as follows : 1 ) In January 2013 , a set of improved canopy automatic multi - angle hyperspectral observation system is installed on the flux tower of Qianfuzhou ecological network experiment station in Jiangxi Province . or ( 42 deg . , 52 deg . , 62 . ) and the instantaneous solar zenith angle , the observed azimuth range is 45 . to 325 . ( north is the origin ) . The spectral data obtained can be used to calculate canopy reflectance and photochemical reflection index after pretreatment with white board correction and dark current correction .
2 ) In the subtropical coniferous forest , the photochemical reflection index and the light energy utilization rate of half an hour show obvious diurnal variation and seasonal variation . In general , the correlation between the photochemical reflection index and the light energy utilization rate is more relevant in the whole growing season . In conclusion , the photochemical reflection index is more sensitive to the light energy utilization rate in the whole growing season .
3 ) In order to improve the ability of the index to monitor the change of light energy utilization rate , the crown layer is regarded as two big leaves , namely the male and female leaves . In the half - hour scale , the ability to detect low to moderate drought stress affects the utilization of light energy is remarkable , but it is not effective to detect severe atmospheric drought and high temperature stress . This may be due to the increase in the proportion of energy that cannot be fixed by other means such as photorespiration dissipation photosynthesis when plants suffer severe stress , and the canopy photochemical reflection index cannot detect this change . In general , the two - leaf algorithm effectively reduces some non - physiological factors , such as the external interference caused by the solar observation geometry to the photochemical reflection index .
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：Q945.11
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本文編號(hào)：1932801