夏琳琳,張 妍,李名鏡

1 北京師范大學(xué)環(huán)境學(xué)院, 環(huán)境模擬與污染控制國家重點聯(lián)合實驗室, 北京 100875 2 暨南大學(xué)環(huán)境學(xué)院,廣州市環(huán)境暴露與健康重點實驗室,廣東省環(huán)境污染與健康重點實驗室,廣州 510632

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城市碳代謝過程研究進(jìn)展

夏琳琳1, 2,張 妍1,*,李名鏡1

1 北京師范大學(xué)環(huán)境學(xué)院, 環(huán)境模擬與污染控制國家重點聯(lián)合實驗室, 北京 100875 2 暨南大學(xué)環(huán)境學(xué)院,廣州市環(huán)境暴露與健康重點實驗室,廣東省環(huán)境污染與健康重點實驗室,廣州 510632

碳代謝過程分析是城市代謝研究的重要環(huán)節(jié),而通過土地利用/覆蓋的空間調(diào)整優(yōu)化城市碳代謝過程已成為區(qū)域可持續(xù)發(fā)展的關(guān)鍵。利用城市代謝思想,本文綜述了城市碳代謝過程核算、碳代謝網(wǎng)絡(luò)模擬、碳代謝過程與土地利用/覆蓋變化關(guān)系分析、碳代謝空間格局演替等方面的內(nèi)容,并指出了當(dāng)前研究中存在著空間屬性表達(dá)缺乏、核算/模擬結(jié)果較難直接應(yīng)用于實踐調(diào)控、自然和社會經(jīng)濟(jì)代謝過程難以并重考慮等問題。在此基礎(chǔ)上,提出了此領(lǐng)域未來發(fā)展預(yù)期：(1)基于土地流轉(zhuǎn),將碳排放/碳吸收垂向流映射到碳存量變化的水平流,以“存量”變化推導(dǎo)出網(wǎng)絡(luò)“流量”分布,實現(xiàn)節(jié)點、流互動關(guān)系的空間表達(dá),構(gòu)建時空維度碳代謝網(wǎng)絡(luò)模型；(2)強(qiáng)調(diào)自然節(jié)點在城市碳代謝網(wǎng)絡(luò)中的重要作用,形成社會經(jīng)濟(jì)節(jié)點與自然節(jié)點并重的生態(tài)網(wǎng)絡(luò)模型,有效服務(wù)于城市規(guī)劃及設(shè)計。

城市碳代謝；生態(tài)網(wǎng)絡(luò)；土地利用/覆蓋變化；空間分析

類比生物體新陳代謝過程,城市代謝是指城市吞吐、消納物質(zhì)和能量的過程,其研究為理解城市可持續(xù)發(fā)展提供了有效的工具與手段。自1965年Wolman首次明確了城市代謝的概念,并開展了假想的百萬人口城市代謝分析之后[1],一些學(xué)者應(yīng)用城市代謝的思想,開展了單一物質(zhì)流或元素的代謝過程研究。同時,隨著全球氣候變化愈加重要,面對著碳排放量的居高不下,碳作為城市代謝過程的關(guān)鍵要素不斷受到人們的關(guān)注[2-3]。城市碳代謝過程的研究十分復(fù)雜,早期開展的流量核算是研究基礎(chǔ),而從“網(wǎng)絡(luò)”視角模擬與分析碳代謝過程,為進(jìn)一步探求其內(nèi)在作用機(jī)理及運行規(guī)律提供了技術(shù)方法支撐。在此基礎(chǔ)上,開展的土地利用/覆蓋變化與碳代謝過程的關(guān)聯(lián)研究,可將碳代謝的研究結(jié)果落實到土地上,并賦予其空間屬性,為低碳城市的規(guī)劃與設(shè)計、碳減排提供科學(xué)支持。本文將從4個方面對碳代謝過程的研究情況進(jìn)行梳理,即碳代謝過程核算、碳代謝網(wǎng)絡(luò)分析與模擬、碳代謝過程與土地利用/覆蓋變化的響應(yīng)關(guān)系分析,以及碳代謝過程空間格局研究,這4個方面的研究進(jìn)展充分體現(xiàn)了城市碳代謝過程整合社會經(jīng)濟(jì)和自然組分、融合時間與空間維度的雙重屬性特征。

1 碳代謝過程核算

碳代謝過程核算以城市代謝為基本框架,追蹤碳在整個城市生態(tài)系統(tǒng)中的流動過程,其研究可以很好地理解城市碳元素的流轉(zhuǎn)過程及其環(huán)境影響[4]。早期的碳核算研究可以追溯至1969年,研究者將工業(yè)、居民消費、交通等活動產(chǎn)生的碳排放納入到美國物質(zhì)流核算框架體系中,同時還考慮了林業(yè)和水域的碳匯[5]。此后,一系列碳流核算框架不斷發(fā)展,使得追蹤城市碳流動的研究更加有據(jù)可循。1993年ICLEI[6]發(fā)起了城市碳減排計劃,重點核算了能源消耗產(chǎn)生的碳排放,開啟了城市尺度碳核算的先河；1998年WRI/WBCSD[7]從理論上提出了城市外部電力、熱力輸入以及跨界交通、廢棄物處置等活動產(chǎn)生的間接碳排放的核算思路與方法；2006年IPCC[8]也建立了燃料缺省碳排放因子體系,為城市碳核算研究提供了可參考的經(jīng)驗系數(shù)。

基于這些研究框架,一些學(xué)者針對不同城市、不同社會經(jīng)濟(jì)活動開展了碳核算研究,如Los Angeles County、Greater Prague等10個城市資源能源消耗、交通電力增加、建成區(qū)設(shè)計等活動的碳排放[9],Barcelona港口城市交通運輸活動的碳排放[10],以及廈門市居民住宅區(qū)能源消耗的碳排放[11]。還有一些研究在考慮社會經(jīng)濟(jì)活動碳排放過程的基礎(chǔ)上,分析了從大氣圈到生物圈的自然碳吸收過程,如Baccini[12]除考慮Swiss Lowland食品加工、工業(yè)貿(mào)易、能源轉(zhuǎn)化、居民消耗和廢物管理等社會經(jīng)濟(jì)活動的碳排放外,還考慮了農(nóng)業(yè)活動的碳排放,并關(guān)注農(nóng)田和森林的碳吸收過程；Kellett 等[13]在核算溫哥華建筑和機(jī)動車能源消費碳排放的同時,考慮了植被的碳儲量；Zhang等[14]全過程核算了北京自然活動產(chǎn)生的生物代謝流和社會經(jīng)濟(jì)活動產(chǎn)生的技術(shù)代謝流。同時,還有學(xué)者解析核算了社會經(jīng)濟(jì)系統(tǒng)內(nèi)部商品、服務(wù)傳遞過程中隱含的碳元素流動,但這些研究僅將自然視為一個組分,沒有深入剖析自然環(huán)境內(nèi)部的碳代謝過程[15-16]。

從以上研究不難看出,目前城市碳代謝核算研究大多關(guān)注局部過程,或集中于碳排放、碳吸收的重要代謝路徑,或集中于社會經(jīng)濟(jì)過程弱化自然過程。對于一個完整的城市碳代謝過程而言,不僅應(yīng)當(dāng)包括社會經(jīng)濟(jì)組分的碳排放,還應(yīng)包括自然組分的碳排放與碳吸收,以及社會經(jīng)濟(jì)、自然組分內(nèi)部的碳流轉(zhuǎn),如圖1所示。只有利用城市代謝方法追蹤生態(tài)系統(tǒng)的碳流動的全過程,才能有效服務(wù)于城市低碳規(guī)劃及設(shè)計。

圖1 城市碳代謝過程核算的發(fā)展[9,16-17]Fig.1 The accounting development of urban carbon metabolism

2 碳代謝網(wǎng)絡(luò)分析與模擬

當(dāng)前,以“網(wǎng)絡(luò)”視角來分析與模擬碳代謝過程逐漸成為研究主流。城市碳代謝過程涉及到多類型代謝主體、多種傳遞路徑,各主體及路徑之間相互影響又形成了復(fù)雜的作用關(guān)系,這為構(gòu)建碳代謝網(wǎng)絡(luò)模型提供了可能。在采用生態(tài)網(wǎng)絡(luò)方法分析、模擬碳代謝過程中,形成了一系列指標(biāo)來表征主體、路徑、網(wǎng)絡(luò)整體的生態(tài)特征,例如通量、協(xié)同指數(shù)和營養(yǎng)級等[16- 18],為定量剖析系統(tǒng)結(jié)構(gòu)與功能提供了有效方法[19-20]。自Hannon[21]初次應(yīng)用生態(tài)網(wǎng)絡(luò)方法,分析模擬生態(tài)系統(tǒng)的結(jié)構(gòu)分布及各營養(yǎng)級之間的相互作用關(guān)系以來,該方法在描述系統(tǒng)內(nèi)部不同組分間物質(zhì)和能量流動等方面已愈發(fā)成熟[19,22]。生態(tài)網(wǎng)絡(luò)分析最早在自然生態(tài)系統(tǒng)中得到了廣泛的應(yīng)用[23-24],2009年Zhang等將該方法引入到城市水代謝分析中,開啟了采用生態(tài)網(wǎng)絡(luò)方法研究社會經(jīng)濟(jì)代謝過程的新方式。

當(dāng)前流量和效用分析在城市代謝中得到了初步應(yīng)用[25]。生態(tài)網(wǎng)絡(luò)流量分析方法可以探尋影響城市碳代謝的關(guān)鍵過程,如Zhang等[18]識別了工業(yè)、交通等28個社會經(jīng)濟(jì)部門之間的能源流動過程,構(gòu)建了北京城市網(wǎng)絡(luò)模型,并對其碳足跡進(jìn)行分析,研究指出社會服務(wù)、消費和重工業(yè)等部門為關(guān)鍵節(jié)點,還有學(xué)者基于土地流轉(zhuǎn)構(gòu)建碳代謝過程的網(wǎng)絡(luò)模型,指出交通與農(nóng)業(yè)之間的轉(zhuǎn)化為網(wǎng)絡(luò)關(guān)鍵路徑[26]。一些學(xué)者進(jìn)一步采用綜合流量分析,識別了間接效益對于代謝過程的影響,研究指出間接作用是削減碳足跡的關(guān)鍵[18]。關(guān)鍵節(jié)點和路徑的識別可以根據(jù)不同部門的排放特征,有針對性地提出碳減排建議[27]。生態(tài)網(wǎng)絡(luò)效用分析則可以定量模擬代謝主體之間的生態(tài)關(guān)系,并結(jié)合流量分析辨識網(wǎng)絡(luò)的生態(tài)層階結(jié)構(gòu)[28]。通過這種方式所判定的生態(tài)層階結(jié)構(gòu)已經(jīng)成為對城市生態(tài)系統(tǒng)的代謝障礙進(jìn)行診斷的有效途徑。就生態(tài)關(guān)系定量研究而言,一些學(xué)者重點分析了社會經(jīng)濟(jì)主體之間的關(guān)系構(gòu)成,如針對香港和維也納的碳代謝網(wǎng)絡(luò)模型,分析了工業(yè)、交通和農(nóng)業(yè)等經(jīng)濟(jì)部門之間的關(guān)系結(jié)構(gòu),認(rèn)為環(huán)境是被社會經(jīng)濟(jì)主體掠奪的主要對象[15-16]。此外,共生和競爭關(guān)系也是社會經(jīng)濟(jì)代謝主體間存在的生態(tài)關(guān)系類型,前者是可維持代謝過程的共生水平[29],后者則可以在一定程度上提高代謝效率[25]。就碳代謝網(wǎng)絡(luò)的生態(tài)層階而言,城市很難形成自然生態(tài)系統(tǒng)中常見的金字塔結(jié)構(gòu),系列研究表明,城市層階結(jié)構(gòu)可能會出現(xiàn)紡錘型、橄欖型等不同的結(jié)構(gòu)[18,30]。盡管如此,組織結(jié)構(gòu)合理的社會經(jīng)濟(jì)代謝過程仍有可能形成金字塔結(jié)構(gòu),如Lu等[31]針對北京市社區(qū)尺度的碳代謝過程構(gòu)建網(wǎng)絡(luò)模型,考慮環(huán)境和景觀對消費、能源和服務(wù)等部門的支撐作用,系統(tǒng)形成了較為規(guī)則的金字塔結(jié)構(gòu)。由于城市代謝過程中存量相對難以估算,這限制了存量分析方法在此領(lǐng)域的應(yīng)用,但仍有一些學(xué)者試圖解釋城市代謝過程的存量,主要通過輸入與輸出總量的差值來間接反映存量變化[23,32]。生態(tài)網(wǎng)絡(luò)分析的具體方法如圖2所示。

目前,碳代謝過程的生態(tài)網(wǎng)絡(luò)分析與模擬研究中,大多關(guān)注于社會經(jīng)濟(jì)活動對城市碳代謝過程的影響,較少考慮自然環(huán)境或不同自然主體的屬性差異,如在碳代謝網(wǎng)絡(luò)模型構(gòu)建中或?qū)h(huán)境統(tǒng)歸為一個節(jié)點[15],或?qū)h(huán)境劃分為外部和內(nèi)部環(huán)境[16],或?qū)h(huán)境劃分為本地環(huán)境和外部景觀[31],均忽略了自然環(huán)境內(nèi)部組分的屬性差異。但也有較少研究試圖在城市碳代謝過程中區(qū)別環(huán)境內(nèi)部的不同屬性,如Zhang等[26]和Xia等[17]在北京城市碳代謝網(wǎng)絡(luò)分析與模擬研究中,初次將不同屬性的自然代謝主體(林地、草地等)納入到生態(tài)網(wǎng)絡(luò)模型中,并指出不同自然代謝主體對流量、關(guān)系結(jié)構(gòu)的貢獻(xiàn)都存在差異,但目前對自然主體參與碳代謝過程的研究還相對粗略,同時,由于數(shù)據(jù)的高度聚合也給不同社會經(jīng)濟(jì)活動的空間映射研究帶來一定的困難,從而導(dǎo)致碳代謝過程的空間分析并不充分。

圖2 生態(tài)網(wǎng)絡(luò)分析方法及在城市碳代謝研究中應(yīng)用[18,26,31-32]Fig.2 Application of ecological analysis in urban carbon metabolism

3 碳代謝過程與土地利用/覆蓋變化響應(yīng)關(guān)系

土地利用/覆蓋變化對碳生物地球化學(xué)循環(huán)過程的影響已成為僅次于化石能源燃燒的第二大因素,通過土地利用/覆蓋變化調(diào)整來促進(jìn)區(qū)域低碳發(fā)展已成為世界各國研究的重點[33]。城市作為碳排放的重點地區(qū),約有1/3碳排放來自于土地利用變化[8],因此,從土地利用/覆蓋角度探討城市碳代謝過程的研究可有效指導(dǎo)城市規(guī)劃和設(shè)計的實踐[34]。

國外學(xué)術(shù)界早在1977年便開始了LUCC與陸地生態(tài)系統(tǒng)碳循環(huán)的關(guān)系研究,得出土地整理是導(dǎo)致大氣CO2含量增加的重要結(jié)論[35]。各國學(xué)者開展了生物群落層次上的自然生態(tài)系統(tǒng)研究[36- 38],如森林生態(tài)系統(tǒng)[39-40]和草地生態(tài)系統(tǒng)[41-42]等,認(rèn)為“還林還草”活動可以有效增加碳吸收,而森林的“碳失匯”過程[43-44],以及草地和森林轉(zhuǎn)化為農(nóng)田[45]等過程也間接增加了碳排放。這些研究識別了不同自然生態(tài)系統(tǒng)的屬性差異,為城市尺度的研究奠定了基礎(chǔ)。隨著研究技術(shù)的發(fā)展,城市尺度碳收支的核算從實地調(diào)查、資料收集估算[46-47],發(fā)展為結(jié)合經(jīng)驗數(shù)據(jù)的模型模擬[48-49],以及3S技術(shù)遙感估算[50-51]。為了實現(xiàn)不同的研究目的,研究者采用多手段多技術(shù)結(jié)合的方式使城市尺度的碳收支估算更加準(zhǔn)確,如模型與遙感結(jié)合[52-53],實地調(diào)查和模型模擬結(jié)合[54-55]、實地調(diào)查和遙感結(jié)合[56-57]估算碳通量。

從土地利用/覆蓋變化角度開展城市碳代謝過程研究需承接城市尺度的碳收支核算工作[12],如一些學(xué)者采用實地調(diào)查和模型結(jié)合的方式核算了碳代謝過程,并關(guān)注了土地利用/覆蓋變化中碳存量增加和減少的過程[58]。城市碳代謝過程與土地利用/覆被變化的關(guān)系研究結(jié)合了城市代謝的思想,更加注重診斷“代謝障礙”,治愈“代謝疾病”,如街區(qū)尺度的可持續(xù)城市規(guī)劃設(shè)計[59],以及針對城市擴(kuò)張的土地利用/覆蓋優(yōu)化布局[56]等。相對于群落層次的自然生態(tài)系統(tǒng)研究,城市碳代謝過程與土地利用/覆蓋變化響應(yīng)關(guān)系的研究還需考慮到社會經(jīng)濟(jì)活動對城市碳代謝過程的影響,包括人工管理活動增加植被碳吸收能力[60],人類干擾造成自然組分的減少[61]以及自然景觀的破碎化[4,62]。從土地利用/覆蓋變化角度探求碳代謝過程的動態(tài)變化規(guī)律的研究示意圖見圖3,在該理論框架下,分析自然和社會經(jīng)濟(jì)代謝活動與土地過程之間的脅迫與響應(yīng)關(guān)系將是未來研究的重點。

圖3 城市碳代謝與土地利用/覆蓋變化響應(yīng)關(guān)系分析示意圖[9,32]Fig.3 The corresponds between urban cabon metabolism and land use/cover change

4 碳代謝過程的空間格局

碳代謝過程空間格局的研究現(xiàn)狀,應(yīng)用與發(fā)展見圖4。隨著城市結(jié)構(gòu)在減緩碳排放方面的作用日益重要,研究者開始進(jìn)行碳收支的空間分異研究[63-64]。城市化導(dǎo)致了土地利用/覆蓋變化,進(jìn)而形成了復(fù)雜的城市空間結(jié)構(gòu)[65],并通過自然植被的破碎化影響著城市環(huán)境[66],導(dǎo)致了碳收支的空間差異[67]。不同城市之間,城市內(nèi)不同區(qū)域之間都存在顯著的碳收支分布格局差異。不同城市的碳排放貢獻(xiàn)定量核算表明,中國和亞洲等地的城市表現(xiàn)為碳源,而其他區(qū)域正在或?qū)⒂商荚崔D(zhuǎn)變?yōu)樘紖R[55],而不同城市林地的碳匯核算表明碳吸收空間分布也存在差異[64],以美國城市為例,其中北部、西北部城市碳匯較大,而西北部城市碳匯則較小[68]。就城市內(nèi)部而言,研究者根據(jù)自然組分的變化確定碳通量差異,將城市不同區(qū)域劃分為綠地區(qū)、貧民區(qū)和建成區(qū)[69]。還有學(xué)者以城市中心為標(biāo)尺分析碳排放和碳吸收的空間格局差異,即距離城市中心越近碳排放越大,碳吸收越小[70]。在以上研究基礎(chǔ)上,有學(xué)者從代謝視角展開空間格局研究,發(fā)現(xiàn)碳代謝過程的空間格局呈現(xiàn)出相似的特性,即顯著的空間梯級變化特性,如Helsinki的碳吸收在空間上呈現(xiàn)多中心梯級遞減[56],北京城市碳代謝過程研究同樣顯示出較為顯著的空間梯級變化,碳排放呈現(xiàn)單中心梯級遞減,碳吸收則呈現(xiàn)多中心梯級遞減[32]。

碳收支空間格局的研究通常以碳核算為基礎(chǔ),且基于不同核算方法,碳收支的空間表達(dá)方式也存在差異。通過遙感數(shù)據(jù)反演地表碳排放濃度[71]以及碳存量的空間分布[72]較為常見,該方法依賴于所能獲得的遙感數(shù)據(jù)精度。而在核算的基礎(chǔ)上結(jié)合GIS技術(shù)對確定邊界內(nèi)碳排放和碳吸收[73-76]進(jìn)行賦值的空間表達(dá)方法可操作性較強(qiáng),但對空間格局的細(xì)節(jié)特征表征不足。一些學(xué)者基于碳收支空間梯度研究,結(jié)合決策系統(tǒng),識別適合城市發(fā)展的最佳策略,如對芬蘭首都Helsinki[56]而言,區(qū)域保護(hù)主義的發(fā)展策略由于建設(shè)用地擴(kuò)張較少,因此對碳代謝格局的影響最小,而對于英國首都London而言,區(qū)域融合式的高效發(fā)展有助于提高區(qū)域植被覆蓋[57]。

目前,相關(guān)研究成果更加傾向于將碳排放/碳吸收空間分布作為環(huán)境表現(xiàn)的指標(biāo),評價不同城市發(fā)展策略對碳代謝空間格局的影響,不能很好地服務(wù)于政策制定。因此,未來研究應(yīng)當(dāng)更加注重碳代謝主體之間關(guān)系、結(jié)構(gòu)的空間解析,為城市空間調(diào)控提供關(guān)鍵信息,支持城市生態(tài)空間優(yōu)化與管理。

圖4 碳代謝過程空間格局研究的現(xiàn)狀、應(yīng)用與發(fā)展[32,56]Fig.4 Spatial pattern of carbon metabolism: current status, applications and prospects

5 未來研究方向

構(gòu)建和諧有效的城市生態(tài)網(wǎng)絡(luò)已然成為實現(xiàn)碳減排目標(biāo)、開展城市生態(tài)規(guī)劃與設(shè)計的重要任務(wù)[77]。當(dāng)前城市碳代謝過程研究大多通過不同部門消耗的物質(zhì)能源量來指導(dǎo)城市設(shè)計[9],而基于網(wǎng)絡(luò)思維所構(gòu)建的城市生態(tài)網(wǎng)絡(luò)著眼于路徑中“流”的核算,但還無法實現(xiàn)空間的直觀表達(dá),從而不能對城市空間進(jìn)行方向和幅度的調(diào)整。而景觀生態(tài)網(wǎng)絡(luò)研究雖能夠在空間上判定可能路徑,但無法確定真正的流量與流向,不能量化描述城市碳代謝過程[78]。兩類生態(tài)網(wǎng)絡(luò)的研究各有側(cè)重,前者傾向描述社會經(jīng)濟(jì)活動,后者則描述自然活動,結(jié)合兩者開發(fā)城市碳代謝過程空間網(wǎng)絡(luò)模型將是未來研究的重點。針對當(dāng)前城市碳代謝過程網(wǎng)絡(luò)分析強(qiáng)調(diào)社會經(jīng)濟(jì)節(jié)點的現(xiàn)狀,突出自然節(jié)點的貢獻(xiàn),將自然和社會經(jīng)濟(jì)活動等代謝主體置于網(wǎng)絡(luò)中同等重要的位置,充分考慮社會經(jīng)濟(jì)活動對自然節(jié)點的影響,以及自然節(jié)點對社會經(jīng)濟(jì)節(jié)點的資源供給與廢物接納作用,全面實現(xiàn)碳代謝過程結(jié)構(gòu)-功能-格局的定量模擬與調(diào)控。同時,為了賦予網(wǎng)絡(luò)空間屬性,將空間維度信息加入網(wǎng)絡(luò),基于土地流轉(zhuǎn),將碳排放/碳吸收等垂直流映射到碳存量變化的水平流,以“存量”變化推導(dǎo)出網(wǎng)絡(luò)“流量”分布,實現(xiàn)節(jié)點、流互動關(guān)系的空間表達(dá),最終構(gòu)建時空維度碳代謝網(wǎng)絡(luò)模型。在城市尺度上構(gòu)建鏈接人工組分和自然組分的碳代謝空間網(wǎng)絡(luò),通過控制關(guān)鍵代謝過程的空間整合優(yōu)化城市空間格局[79]。

圖5 碳代謝過程的空間網(wǎng)絡(luò)模型Fig.5 The conceptual model of a city′s spatial carbon metabolism networkF1：有林地；F2：灌木林地；F3：疏林地；F4：其他林地；G1：高覆蓋草地；G2：中覆蓋草地；G3：低覆蓋草地；W1：河流；W2：水庫；W3：濕地；U：城鎮(zhèn)；R：農(nóng)村；T交通工礦；B1：沙地；B2：裸地；B3：裸巖石質(zhì)地；C1：水田；C2：旱地V1—V8為大氣圈與生物圈之間的碳交換過程,黃色虛線為生物圈中碳轉(zhuǎn)移過程

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A review of urban carbon metabolism

XIA Linlin1,2, ZHANG Yan1,*, LI Mingjing1

1StateKeyJointLaboratoryofEnvironmentalSimulationandPollutionControl,SchoolofEnvironment,BeijingNormalUniversity,Beijing100875,China2SchoolofEnvironment,GuangzhouKeyLaboratoryofEnvironmentalExposureandHealth,andGuangdongKeyLaboratoryofEnvironmentalPollutionandHealth,JinanUniversity,Guangzhou510632,China

Carbon metabolism is the key process of the urban metabolic system. The optimization of carbon metabolism through land use/cover change and spatial adjustment has been the focus of sustainable development in urban areas. Under the framework of urban metabolism, this paper includes a comprehensive review of carbon metabolic process accounting, ecological network analysis of urban carbon metabolism, the relationship between carbon metabolism and land use/cover change, and the spatial patterns of carbon metabolism. This paper summarizes the insufficiencies of current research, including insufficient spatial analysis of the network of carbon metabolism, limitations to practical application of carbon budget and modeling results, and the disparity between natural and social-economic activities in the same system. Finally, future needs in research are proposed: 1) A spatially explicit network model of urban carbon metabolism should be built within the perspective of land use/cover change. The model should investigate network flows, using carbon emission and sequestration accounting results, which could represented the carbon storage of the biosphere. Then, the flows between any two nodes of the network could be deduced by accounting for changes in storage. The spatial expression of the interaction between any two nodes could be explored using the model. 2) The model should also focus on natural activities in the urban metabolic system. The network model should include both natural and socio-economic nodes and should be constructed to support urban planning.

urban carbon metabolism; ecological network; land use and cover change; spatial analysis

國家重點研發(fā)計劃項目(2016YFC0503005)；新世紀(jì)優(yōu)秀人才支持計劃“生態(tài)模擬”(NCET- 12-0059)；國家自然科學(xué)基金創(chuàng)新研究群體項目“流域水環(huán)境、水生態(tài)和綜合管理”(51421065)；國家自然科學(xué)基金面上項目 “京津冀城市群能源-污染物代謝過程-格局-機(jī)理研究”(41571521)；中央高?；究蒲袠I(yè)務(wù)費專項資金“城市能量代謝過程及其碳足跡分析”(2015KJJCA09)；中美國際(地區(qū))合作交流項目(51661125010)

2016- 06- 15;

2017- 02- 21

10.5846/stxb201606151160

*通訊作者Corresponding author.E-mail: zhangyanyxy@126.com

夏琳琳,張妍,李名鏡.城市碳代謝過程研究進(jìn)展.生態(tài)學(xué)報,2017,37(12):4268- 4277.

Xia L L, Zhang Y, Li M J.A review of urban carbon metabolism.Acta Ecologica Sinica,2017,37(12):4268- 4277.