根據(jù)政府間氣候變化專門委員會（IPCC）第六次評估報告顯示，2011年至2020年平均氣溫較工業(yè)化前增高1.09℃?！半p碳”行動是應(yīng)對全球氣候變暖的重要舉措，截至2021年4月，已有130多個國家和地區(qū)擬議了“零碳”或“碳中和”氣候目標(biāo)。碳中和一般從碳源（碳排放）和碳匯（碳固定）的角度進(jìn)行理解，包含了自然過程和人為過程。生態(tài)系統(tǒng)在固碳中發(fā)揮重要作用，國內(nèi)的森林大都處于幼年期，在樹木的適齡期內(nèi)，固碳作用可持續(xù)進(jìn)行，同時，還有不少可造林面積，加之草地、濕地、農(nóng)田土壤的碳大都處于不飽和狀態(tài)，因此，生態(tài)系統(tǒng)的固碳潛力巨大。而風(fēng)景園林作為城市生態(tài)系統(tǒng)的重要構(gòu)成，是城市中唯一有生命的具有碳匯功能的基礎(chǔ)設(shè)施，也是實現(xiàn)人口高密區(qū)碳中和的主要組成部分。

廣義的風(fēng)景園林，是城市區(qū)域內(nèi)包含森林、濕地、綠地、水體等要素的生態(tài)系統(tǒng)，其助力碳中和的途徑主要通過植被、土壤和水體的減源和增匯來實現(xiàn)。植物配置以適應(yīng)性、抗性、固碳能力較強(qiáng)的地帶性鄉(xiāng)土植物為主，綜合考慮植物壽命、規(guī)格、常綠與落葉配比、幼齡與老齡配比、群落相生相克、落地與架空等因素；土壤碳匯能力顯著強(qiáng)于植被碳匯，通過改良土壤肥力、生物活性和物理結(jié)構(gòu)，可充分發(fā)揮土壤的碳固持能力；水體質(zhì)量、水生植物配置、水下土壤等是水體碳匯需重點關(guān)注的內(nèi)容。從風(fēng)景園林空間布局而言，在“雙碳”政策和公園城市建設(shè)理念下，以生態(tài)建設(shè)目標(biāo)為引領(lǐng)，推進(jìn)綠地、林地、濕地等融合發(fā)展，優(yōu)化布局體系，持續(xù)增強(qiáng)生態(tài)系統(tǒng)的碳匯能力。從管控的角度，風(fēng)景園林建設(shè)和管理養(yǎng)護(hù)過程中要控制碳排放、降低能源消耗，以達(dá)到“低維護(hù)”目標(biāo)，尋求碳平衡；以科學(xué)表征為基礎(chǔ)，尊重自然規(guī)律，遵循高碳匯的作用機(jī)理。

本期專題“科技創(chuàng)新助力碳中和”，涵蓋宏觀規(guī)劃到微觀實踐的研討，進(jìn)一步厘清了碳中和目標(biāo)下風(fēng)景園林減碳增匯的基本邏輯以及技術(shù)需求。提出“雙碳”戰(zhàn)略是換跑道，而不是原道超車，需通過一系列顛覆性變革，在新一輪產(chǎn)業(yè)革命中獲得主角地位等革新思考；剖析碳中和背景下全球11個國家的30項相關(guān)規(guī)劃行動，構(gòu)建城市綠地適應(yīng)性規(guī)劃“目標(biāo)—策略—指標(biāo)”總體技術(shù)框架，提出“市域—城區(qū)—街區(qū)—地塊”四級管控層級，并差異化制定了多尺度精準(zhǔn)增效規(guī)劃策略和多層級評估管控指標(biāo)；基于自然的解決方案的綠色空間韌性—降碳協(xié)同范式與設(shè)計策略，提出全周期迭代演進(jìn)的動態(tài)適應(yīng)性范式和七項原則性策略；抽樣城市街道的行道樹，運用i-Tree Streets模型對街道空間的碳儲效益比、CO2吸收效益、節(jié)能效益等構(gòu)成的低碳綜合效益進(jìn)行評估測算，提出街道空間精細(xì)化改造提升建議。

實現(xiàn)碳中和是一項極具挑戰(zhàn)性的系統(tǒng)工程。從“達(dá)峰”到“中和”，控碳、減碳、低碳、中和是必經(jīng)的過程階段。“達(dá)峰”與“中和”之間是有鴻溝的，沒有系統(tǒng)性的社會變革，沒有顛覆性的技術(shù)革命，很難實現(xiàn)從量變到質(zhì)變的躍遷。當(dāng)前，“雙碳”目標(biāo)依賴自上而下的制度牽引已成為共識，如何切實推進(jìn)法律法規(guī)充分發(fā)揮其保障作用，任重而道遠(yuǎn)。

主編

2022年12月20日

The Basic Logic of Carbon Sink Capacity Construction of Landscape Architecture

According to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), the average temperature from 2011 to 2020 increased by 1.09℃ compared with pre-industrial period.The “double carbon” action is an important measure to deal with global warming.As of April 2021, more than 130 countries and regions have proposed “zero carbon” or “carbon neutrality” climate goals.Carbon neutrality is generally understood from the perspective of carbon sources (carbon emissions) and carbon sinks (carbon sequestration), including natural and man-made processes.Ecosystems play an important role in carbon sequestration.Most forests in China are in their infancy, and carbon sequestration can be carried out continuously in the right age of trees.At the same time, there is still a lot of afforestation area, and the carbon of grassland, wetland and farmland soil is mostly in the unsaturated state,so the carbon sequestration potential of the ecosystem is huge.As an important component of urban ecosystem, landscape architecture is the only living infrastructure with carbon sink function in the city, and also the main component of carbon neutrality in high-density population area.

Broadly speaking, landscape architecture is an ecosystem containing forest,wetland, green space, water and other elements in an urban area.Its contribution to carbon neutrality is mainly achieved through reducing the source and increasing the sink of vegetation, soil and water.The plant configuration is dominated by zonal native plants with strong adaptability, resistance and carbon sequestration ability.Factors such as plant life, size, ratio of evergreen to deciduous, ratio of young to old, community interaction and conflict, ground and aerial are considered comprehensively.Soil carbon sequestration capacity is significantly stronger than vegetation carbon sequestration capacity.Soil carbon sequestration capacity can be fully exerted by improving soil fertility, biological activity and physical structure.Water quality, aquatic plant configuration,underwater soil and so on are the key contents of water carbon sink.In terms of the spatial layout of landscape architecture, under the “double carbon” policy and the concept of urban park construction, the integrated development of green space, woodland and wetland should be promoted, the layout system should be optimized, and the carbon sink capacity of the ecosystem should be continuously enhanced.From the perspective of management and control, carbon emissions and energy consumption should be controlled and reduced during the construction, management and maintenance of landscape architecture, so as to achieve the goal of “l(fā)ow maintenance” and seek carbon balance.

The topic of this issue, “Scientific and Technology Innovation Promotes Carbon Neutrality”, covers the discussion from macro planning to micro practice, and further clarifies the basic logic and technical requirements of landscape architecture for carbon reduction and sink increase of landscape architecture under the goal of carbon neutrality.It was proposed that the “double carbon” strategy is to change the runway instead of overtaking the original road, and it needs to obtain the leading role in the new round of industrial revolution through a series of subversive changes.30 relevant planning actions in 11 countries were analyzed, and multi-scale precise efficiency planning strategies and multi-level evaluation and control indicators were differentiated.Based on the green space resilience and carbon reduction collaborative paradigm and design strategy of natural solutions, the dynamic adaptability paradigm and seven principle strategies of the whole cycle iterative evolution were proposed.Besides, the i-Tree Streets model was used to evaluate and calculate the comprehensive benefit of low carbon of street space by sampling street trees of urban streets, and the suggestions on refinement and improvement of street space were put forward.

Achieving carbon neutrality is a very challenging systematic engineering.From “peak” to “neutralization”, carbon control, carbon reduction, low-carbon and neutralization is the necessary process stage.There is a gap between “peak” and“neutralization”.Without systematic social change and subversive technological revolution, it is difficult to realize the transition from quantitative change to qualitative change.At present, it has become a consensus that the goal of “double carbon” relies on top-down institutional traction.It is still a long way to go to effectively promote laws and regulations to give full play to their safeguarding role.

Editor-in-Chief

December 20th, 2022