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Threshold of climate extremes that impact vegetation productivity over the Tibetan Plateau

Science China Earth sciences 2024年第6期67卷 1967-1977页

作者： Zhenggang PIAO Xiangyi LI Hao XU Kai WANG Shuchang TANG Fei KAN Songbai HONG college of urban and environmental sciences Peking UniversityBeijing 100871China

Vegetation growth is adversely impacted by multiple climate extremes related to the water and thermal stress over the Tibetan Plateau(TP).However,it remains unknown at which stress level these climate extremes can trigger the abrupt shifts of vegetation response to climate extremes and result in the maximum vegetation response across *** fill this knowledge gap,we combined the hydrometeorological data and the satellite-derived vegetation index to detect two critical thresholds that determine the response of vegetation productivity to droughts,high-temperature extremes,and low-temperature extremes,respectively,during *** results show that the response of vegetation productivity to droughts rapidly increases once crossing -1.41±0.6 standard deviation(σ)below the normal conditions of soil *** crossing-2.98σ±0.9σ,vegetation productivity is maximum damaged by ***-temperature extremes,which have the two thresholds of 1.34σ±0.4σand 2.31σ±0.4σover TP,are suggested to trigger the strong response of vegetation productivity at a milder stress level than low-temperature extremes(two thresholds:-1.44σ±0.5σand-2.53σ±0.8σ).Moreover,we found the compounded effects of soil moisture deficit in reducing the threshold values of both high-and low-temperature *** on the derived thresholds of climate extremes that impact vegetation productivity,Earth System Models project that southwestern TP and part of the northeastern TP will become the hotspots with a high exposure risk to climate extremes by *** study deciphers the high-impact extreme climates using two important thresholds across TP,which advances the understanding of the vegetation response to different climate extremes and provides a paradigm for assessing the impacts of climate extremes on regional ecosystems.

关键词： Tibetan Plateau Climate extremes Thresholds Vegetation productivity

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Identification of rural courtyards’utilization status using deep learning and machine learning methods on unmanned aerial vehicle images in north China

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Building Simulation 2024年第5期17卷 799-818页

作者： Maojun Wang Wenyu Xu Guangzhong Cao Tao Liu college of Resource Environment and Tourism Capital Normal UniversityBeijing 100048China college of urban and environmental sciences Peking UniversityBeijing 100871China

The issue of unoccupied or abandoned homesteads(courtyards)in China emerges given the increasing aging population,rapid urbanization and massive rural-urban *** the aspect of rural vitalization,land-use planning,and policy making,determining the number of unoccupied courtyards is *** and questionnaire-based surveys were currently the main approaches,but these traditional methods were often expensive and laborious.A new workflow is explored using deep learning and machine learning algorithms on unmanned aerial vehicle(UAV)***,features of the built environment were extracted using deep learning to evaluate the courtyard management,including extracting complete or collapsed farmhouses by Alexnet,detecting solar water heaters by YOLOv5s,calculating green looking ratio(GLR)by *** precisions exceeded 98%.Then,seven machine learning algorithms(Adaboost,binomial logistic regression,neural network,random forest,support vector machine,decision trees,and XGBoost algorithms)were applied to identify the rural courtyards’utilization *** Adaboost algorithm showed the best performance with the comprehensive consideration of most metrics(Accuracy:0.933,Precision:0.932,Recall:0.984,F1-score:0.957).Results showed that identifying the courtyards’utilization statuses based on the courtyard built environment is *** is transferable and cost-effective for large-scale village surveys,and may contribute to the intensive and sustainable approach to rural land use.

关键词： unoccupied homesteads courtyard built environment inner courtyard management GLR solar water heaters machine learning algorithms

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Plant life form determines spatiotemporal variability and climate response of plant seed rain in subtropical forests

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Forest Ecosystems 2024年第2期11卷 193-201页

作者： Yuyang Xie Zehao Shen Xuejing Wang Liu Yang Jie Zhang MOE Laboratory for Earth Surface Processes Institute of EcologyCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China

Spatiotemporal variation of seed rain reflects the response of plants in terms of their reproductive strategy to environmental *** this study,we collected seeds from four sites in the Dalaoling Nature Reserve,Hubei Province,China,between 2011 and 2014,measured seed output and seed mass as seed rain traits,and compared their interannual and elevational ***,we ran phylogenetic generalized mixed linear models(PGLMMs) to explore the effects of temperature and precipitation as well as interspecific differences on seed rain,and fitted the best regression models for seed rain *** of canopy and understory *** results showed no correlation between values of seed output and seed ***,the variation of the two traits showed significantly positive *** output of canopy species generally decreased with increasing elevation,and showed significant interannual difference;however,seed output of understory species and seed mass for both canopy and understory species did not show consistency tends along elevational or in interannual *** output was significantly affected by temperature and precipitation,while seed mass mainly varied due to interspecific *** explained more the variation of the seed output of canopy species than that of understory species,with R^(2) values of 43.0%and 29.9%,*** results suggested that canopy plants contributed more to the reproductive dynamics of the whole communities,and the canopy's buffer effect on the underground weakened the response of understory plants to weather variation in terms of their reproductive strategy.

关键词： Seed rain Seed output Seed mass Elevation Interannual variation Lifeform

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Innovation and Firm Co-ownership Network in China’s Electric Vehicle Industry

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Chinese Geographical Science 2024年第2期34卷 195-209页

作者： JIN Zerun ZHU Shengjun college of urban and environmental sciences Peking UniversityBeijing 100871China Laboratory for Earth Surface Pro-cesses of the Ministry of Education Peking UniversityBeijing 100871China

Firms are embedded in complex networks,where diverse ideas combine and generate new *** of firms are of-ten seen as critical external resources that have significant influence on firm *** current literature tends to focus on the rela-tionship between firms and their shareholders,while paying less attention to the connections between firms with the same *** article identifies two types of network spillover effects,intra-city network effect and inter-city network effect,by visualizing the co-ownership networks in China’s electric vehicle(EV)*** find that firms with the same shareholders,which are defined as co-owned EV firms,are more innovative than non-co-owned ***,there are two dominant types of firm co-ownership ties formed by corporate and financial institution *** corporate shareholders help exploiting local tacit knowledge,financial institutions are more active in bridging inter-city *** conclusion is confirmed at both firm and city *** paper theor-izes the firm co-ownership network as a new form of institutional proximity and tested the result *** policy consideration,we have emphasized the importance of building formal or informal inter-firm network,and the government should further enhance the knowledge flow channel by institutional construction.

关键词： firm co-ownership intra-city network inter-city network technological innovation electric vehicle China

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Spatiotemporal Characteristics of Atmospheric Brown Carbon Emission from Combustion Sources in China

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Chinese Geographical Science 2024年

作者： OUYANG Shuyu JIANG Ke XIONG Rui MEN Yatai LUO Zhihan XING Ran SHEN Guofeng college of urban and environmental sciences Peking University college of Ecology and Environment Zhengzhou University Institute of Carbon Neutrality Peking University

Atmospheric Brown Carbon(BrC) with strong wavelength-dependence light-absorption ability can significantly affect radiative forcing. Highly resolved emission inventories with lower uncertainties are important premise and essential in scientifically evaluating impacts of emissions on air quality, human health and climate change. This study developed a bottom-up inventory of primary BrC from combustion sources in China from 1960 to 2016 with a spatial resolution at 0.1° × 0.1°, based on compiled emission factors and detailed activity data. The primary BrC emission in China was about 593 Gg(500–735 Gg as interquartile range) in 2016, contributing to 7%(5%–8%) of a previously estimated global total BrC emission. Residential fuel combustion was the largest source of primary BrC in China, with the contribution of 67% as the national average but ranging from 25% to 99% among different provincial regions. Significant spatial disparities were also observed in the relative shares of different fuel types. Coal combustion contribution varied from 8% to99% across different regions. Heilongjiang and North China Plain had high emissions of primary BrC. Generally, on the national scale,spatial distribution of BrC emission density per area was aligned with the population distribution. Primary BrC emission from combustion sources in China have been declined since a peak of ～1300 Gg in 1980, but the temporal trends were distinct in different *** high-resolution inventory developed here enables radiative forcing simulations in future atmospheric models so as to promote better understanding of carbonaceous aerosol impacts in the Earth's climate system and to develop strategies achieving co-benefits of human health protection and climate change.

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Analysis of China’s PM_(2.5)and ozone coordinated control strategy based on the observation data from 2015 to 2020

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Journal of environmental sciences 2024年第4期138卷 385-394页

作者： Liuwei Kong Mengdi Song Xin Li Ying Liu Sihua Lu Limin Zeng Yuanhang Zhang State Key Joint Laboratory of environmental Simulation and Pollution Control College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China

The coordinated control of PM_(2.5)and ozone has become the strategic goal of national air pollution *** the gradual decline in PM_(2.5)concentration and the aggravation of ozone pollution,a better understanding of the coordinated control of PM_(2.5)and ozone is urgently ***,we collected and sorted air pollutant data for 337 cities from 2015 to 2020 to explore the characteristics of PM_(2.5)and ozone pollution based on China’s five major air pollution *** results show that it is necessary to continue to strengthen the emission reduction in PM_(2.5)and ozone precursors,and control NO_(x) and VOCs while promoting a dramatic emission reduction in PM_(2.5).The primary method of curbing ozone pollution is to strengthen the emission control of VOCs,with a long-term strategy of achieving substantial emission reductions in NO_(x),because VOCs and NO_(x) are also precursors to PM_(2.5);hence,their reductions also contribute to the reduction in PM_(2.5).Therefore,the implementation of a multipollutant emission reduction control strategy aimed at the prevention and control of PM_(2.5)and ozone pollution is the only means to realize the coordinated control of PM_(2.5)and ozone.

关键词： PM_(2.5) Ozone Coordinated control Multipollutant reduction

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Life forms affect beta-diversity patterns of larch forests in China

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Plant Diversity 2024年第1期46卷 49-58页

作者： Wenjing Fang Qiong Cai Chengjun Ji Jiangling Zhu Zhiyao Tang Jingyun Fang School of Ecology and environmental Science Yunnan UniversityKunming 650091China Department of Ecology College of Urban and Environmental Sciencesand Key Laboratory for Earth Surface Processes of the Ministry of EducationPeking UniversityBeijing 100871China

Beta-diversity reflects the spatial changes in community species composition which helps to understand how communities are assembled and biodiversity is formed and maintained. Larch(Larix) forests, which are coniferous forests widely distributed in the mountainous and plateau areas in North and Southwest China, are critical for maintaining the environmental conditions and species diversity. Few studies of larch forests have examined the beta-diversity and its constituent components(species turnover and nestedness-resultant components). Here, we used 483 larch forest plots to determine the total betadiversity and its components in different life forms(i.e., tree, shrub, and herb) of larch forests in China and to evaluate the main drivers that underlie this beta-diversity. We found that total betadiversity of larch forests was mainly dependent on the species turnover component. In all life forms,total beta-diversity and the species turnover component increased with increasing geographic, elevational, current climatic, and paleoclimatic distances. In contrast, the nestedness-resultant component decreased across these same distances. Geographic and environmental factors explained 20%-25% of total beta-diversity, 18%-27% of species turnover component, and 4%-16% of nestedness-resultant component. Larch forest types significantly affected total beta-diversity and species turnover component. Taken together, our results indicate that life forms affect beta-diversity patterns of larch forests in China, and that beta-diversity is driven by both niche differentiation and dispersal limitation. Our findings help to greatly understand the mechanisms of community assemblies of larch forests in China.

关键词： Beta-diversity Species turnover Nestedness-resultant Geographic distance Climatic distance Larch forest

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A study on the impact of heritage protection on urban carbon emissions

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Science China(Technological sciences) 2024年第9期67卷 2675-2692页

作者： WANG Fang XUE PengCheng WANG ShunYi LIU YunHuai River Basin Habitats Research Center College of Architecture and Landscape ArchitecturePeking UniversityBeijing 100871China Shanxi Key Laboratory of Watershed Built Environment with Locality(peking university) Peking UniversityBeijing 100871China college of urban and environmental sciences Peking UniversityBeijing 100871China School of Computer Science Peking UniversityBeijing 100871China

A major goal of current international urban development and construction is to lower carbon *** exist between the preservation of historic cities and the development of low-carbon cities;however,the relationship between preservation of historic cities and carbon emissions remains *** study focuses on the cities in the“Yellow-Canal-Yangtze”watershed community,which includes the Yellow River Basin,Yangtze River Basin,and the Grand Canal region,and aims to verify the differences in CO_(2) emissions(CE)between historic and non-historic cities through multiple comparisons after ***,Ridge Regression was used to determine the impact and dimensions of the relevant variables associated with the preservation of historic cities on *** with national development goals,this study predicts changes in the CE of historic city preservation under different *** study found significant differences between historic and non-historic cities,as the total CE of historic cities is 2.42 times higher than that of non-historic *** dimension with the largest difference was the CE related to transportation,with aviation emissions of historic cities reaching 15.22 times higher than that of non-historic *** the preservation of historic cities has led to an overall increase in the CE,there is significant potential for CE reduction in land use,transportation infrastructure,and tourism development related to historic city *** the future,historic cities can contribute to China's carbon neutrality and the United Nation's development goals through the creation of larger historical preservation areas,more convenient public transportation,and more vibrant tourism.

关键词： CO_(2) emissions urban planning cultural heritage historic city “Yellow-Canal-Yangtze”watershed community

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Pollutant emissions from biomass burning:A review on emission characteristics,environmental impacts,and research perspectives

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Particuology 2024年第2期85卷 296-309页

作者： Ke Jiang Ran Xing Zhihan Luo Wenxuan Huang Fan Yi Yatai Men Nan Zhao Zhaofeng Chang jinfeng Zhao Bo Pan Guofeng shen college of urban and environmental sciences Peking UniversityBeijing100871China Beijing Key Lab Plant Resources Research and Development Beijing Technology and Business UniversityBeijing100048China college of Ecology and Environment Zhengzhou UniversityZhengzhou450001China Facultyof environmental sciences and Engineering Kunming University of Science and TechnologyYunnan Provincial Key Laboratoryof Soil Carbon Sequestration and Pollution ControlKunming650500China Institute of Carbon Neutrality Peking UniversityBeijing100871China

Biomass is one most abundant resource on the earth providing important energies in support of so-cioeconomic development in many *** of biomass fuels comprises to nearly 10%of the total energy from anthropogenic combustion processes:however,as the burning is usually incomplete,this process yields products of incomplete combustion posing consequently significant impacts on air quality,human health,and climate ***,we analyzed spatiotemporal characteristics in intentional and unintentional biomass burning from different sectors,discussed impacts of biomass burning emissions on indoor and outdoor air quality,and consequent influences on human *** global total con-sumption amount of biomass including both natural and anthropogenic sources was approximately 7900 Tg in 2019,with significantly large regional and sectorial discrepancies among ***,anthropogenic biomass burning amounts increased gradually,but notably in some developing countries like China residential consumption of biomass fuels,as one large sector of biomass use,decreased over *** biomass consumption needs to be accurately *** are relatively rich datasets of pollutant emission factors from biomass burning,including laboratory and field tests,but still large variations exit and contribute substantially to the uncertainty in emission *** pri-mary PM2.5,black carbon and organic carbon emissions from biomass burning were about 51,4.6,and 29 Tg,respectively,contributing to nearly 70%,55%,and 90%of the total emission from all sources,and emissions from the residential sector and open fires are major *** carbon emissions from biomass burning attracts growing interests but available studies adopted different methodologies challenging the comparability of those *** burning emissions polluted not only ambient air but more severely indoor air quality,adversely affecting human *** studies that should be emphasiz

关键词： Biomass burning Carbonaceous aerosol Emission Air quality Human health

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Your personal choices in transportation and food are important for lowering carbon emissions

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Frontiers of environmental Science & Engineering 2024年第6期18卷 27-32页

作者： Bruce Logan Fang Zhang Wulin Yang Le Shi Institute of Energy and the Environment The Pennsylvania State UniversityUniversity ParkPA 16802USA School of Environment Tsinghua UniversityBeijing 100084China college of environmental sciences and Engineering Peking UniversityBeijing 100871China college of environmental and Resource sciences Zhejiang UniversityHangzhou 310058China

There is a global need to reduce greenhouse gas emissions to limit the extent of climate change.A better understanding of how our own activities and lifestyle influence our energy use and carbon emissions can help us enable changes in activities that can lead to reductions in carbon *** we discuss an approach based on examining carbon emissions from the perspective of the unit C,where 1 C is the CO_(2)from food a person would on average eat every *** approach shows that total CO_(2)emissions in China,normalized by the population,is 22.5 C while carbon emissions for a person in the US is 43.9 C.A better appreciation of our own energy use can be obtained by calculating carbon emissions from our own activities in units of C,for example for driving a car gasoline or electric vehicle a certain number of kilometers,using electricity for our homes,and eating different *** this information,we can see how our carbon emissions compare to national averages in different countries and make decisions that could lower our personal CO_(2)emissions.

关键词： Carbon dioxide Climate change Daily energy Greenhouse gas

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