Effects of urbanization and forest type on species composition and diversity,forest characteristics,biomass carbon sink,and their associations in Changchun,Northeast China:implications for urban carbon stock improvement

Differences in forest attributes and carbon sequestration of each organ and layer between broadleaved and conifer forests of central and outer urban areas are not well-defined,hindering the precise management of urban forests and improvement of function.To clarify the effect of two forest types with different urbanization intensities,we determined differences in vegetation composition and diversity,structural traits,and carbon stocks of 152 plots(20 m×20 m)in urban park forests in Changchun,which had the largest green quantity and carbon density effectiveness.We found that 1.1-fold thicker and healthier trees,and 1.6-to 2.0-fold higher,healthier,denser,and more various shrubs but with sparser trees and herbs occurred in the central urban forests(p<0.05)than in the outer forests.The conifer forests exhibited 30–70%obviously higher tree aboveground carbon sequestration(including stem and leaf)and 20%bigger trees,especially in the outer forests(p<0.05).In contrast,1.1-to 1.5-fold higher branch stocks,healthier and more diverse trees were found in broadleaved forests of both the inner and outer forests(p<0.05).Plant size and dominant species had similarly important roles in carbon stock improvement,especially big-sized woody plants and Pinus tabuliformis.In addition,a higher number of deciduous or needle species positively affected the broadleaved forest of the central urban area and conifer forest of the outer urban area,respectively.These findings can be used to guide precise management and accelerate the improvement of urban carbon function in Northeast China in the future.

Examining the Spatiotemporal Dynamics and Determinants of Land Urbanization in Prefecture-level Cities,China

Examining the spatiotemporal dynamics and determinants of land urbanization is critical for promoting healthy urban development and the rational use of land resources.Based on the dataset consisting of land use change data and selected factors in 2010 and2020,this study used visual analysis to reveal the spatiotemporal dynamics of land urbanization across prefecture-level cities in China.Meanwhile,the driving forces underlying land urbanization were examined by using geographical detector technique.Following are the findings:1)we find that there exist notable spatial variances in land urbanization across prefecture-level cities.Currently,the differentiation in land urbanization between the northern and southern cities is more pronounced than that between the coastal and inland cities,or between the eastern and western cities.Prefecture-level cities located in central and western China have experienced the most rapid growth in land urbanization.Conversely,the growth rate in northeastern China is the lowest,while the velocity in eastern China remains relatively stable.By using spatial autocorrelation analysis,this study reveals that the land urbanization level in prefecture-level cities has significant spatial agglomeration.2)We further find that land urbanization in China is influenced by factors related to urban land supply and demand,and urban population growth,economic growth,land financial and political incentive have greater impact on land urbanization than other factors.3)We also find that the impacts of determinants on China’s land urbanization vary over time,the explanatory power of economic development increased,while the explanatory power of state forces declined.We argue that integrating the supply and demand factors of land urbanization can provide a more comprehensive understanding of the driving mechanisms underlying land urbanization in China and other transitional countries,and help decision-makers in these countries formulate more detailed and specific land urbanization policies.

Spatio-temporal Evolution Characteristics and Driving Forces of Winter Urban Heat Island:A Case Study of Rapid Urbanization Area of Fuzhou City,China

Under the influence of anthropogenic and climate change,the problems caused by urban heat island(UHI)has become increasingly prominent.In order to promote urban sustainable development and improve the quality of human settlements,it is significant for exploring the evolution characteristics of urban thermal environment and analyzing its driving forces.Taking the Landsat series images as the basic data sources,the winter land surface temperature(LST)of the rapid urbanization area of Fuzhou City in China was quantitatively retrieved from 2001 to 2021.Combing comprehensively the standard deviation ellipse model,profile analysis and GeoDetector model,the spatio-temporal evolution characteristics and influencing factors of the winter urban thermal environment were systematically analyzed.The results showed that the winter LST presented an increasing trend in the study area during 2001–2021,and the winter LST of the central urban regions was significantly higher than the suburbs.There was a strong UHI effect from 2001 to 2021with an expansion trend from the central urban regions to the suburbs and coastal areas in space scale.The LST of green lands and wetlands are significantly lower than croplands,artificial surface and unvegetated lands.Vegetation and water bodies had a significant mitigation effect on UHI,especially in the micro-scale.The winter UHI had been jointly driven by the underlying surface and socio-economic factors in a nonlinear or two-factor interactive enhancement mode,and socio-economic factors had played a leading role.This research could provide data support and decision-making references for rationally planning urban layout and promoting sustainable urban development.

Impact of air pollution on urbanization:evidence at China’s city level

This paper investigates the effect and transmission mechanism of air pollution on urbanization based on data from China’s 107 cities during 2005–2018.In order to identify the impact of air pollution on China’s urbanization,we utilized night light data to represent the level of urbanization and used temperature inversion as an instrumental variable to mitigate endogeneity within the two-stage least squares framework.The results suggest that air pollution significantly slowed China’s urbanization process with economic growth acting as the transmission mechanism.The heterogeneity analyses revealed that air pollution had a greater negative impact on urbanization in northern regions than that in southern regions,and a greater negative impact in resource-oriented cities than that in non-resource-based cities.We also find that air pollution was to the detriment of urbanization in larger cities,which have more than 3 million residents,while it did not have a significant impact on Type II large cities,which have fewer than 3 million residents.

Local Climate Change Induced by Urbanization on a South China Sea Island

The South China Sea is a hotspot for regional climate research.Over the past 40 years,considerable improvement has been made in the development and utilization of the islands in the South China Sea,leading to a substantial change in the land-use of the islands.However,research on the impact of human development on the local climate of these islands is lacking.This study analyzed the characteristics of local climate changes on the islands in the South China Sea based on data from the Yongxing Island Observation Station and ERA5 re-analysis.Furthermore,the influence of urbanization on the local climate of the South China Sea islands was explored in this study.The findings revealed that the 10-year average temperature in Yongxing Island increased by approximately 1.11℃from 1961 to 2020,and the contribution of island development and urbanization to the local warming rate over 60 years was approximately 36.2%.The linear increasing trend of the annual hot days from 1961–2020 was approximately 14.84 days per decade.The diurnal temperature range exhibited an increasing trend of 0.05℃per decade,whereas the number of cold days decreased by 1.06days per decade.The rapid increase in construction on Yongxing Island from 2005 to 2021 led to a decrease in observed surface wind speed by 0.32 m s^(-1)per decade.Consequently,the number of days with strong winds decreased,whereas the number of days with weak winds increased.Additionally,relative humidity exhibited a rapid decline from 2001 to 2016 and then rebounded.The study also found substantial differences between the ERA5 re-analysis and observation data,particularly in wind speed and relative humidity,indicating that the use of re-analysis data for climate resource assessment and climate change evaluation on island areas may not be feasible.

Research on the Digital Economy's Impact on China's Economic Growth:Based on the Variations in Urbanization Levels Across China's Eastern,Central,and Western Regions and Sectoral Heterogeneity

This paper uses inter-provincial panel data from 2011 to 2017,a linear regression model,and a threshold model to conduct empirical analyses of the impact of the digital economy on China's overall economic growth and the three main sectors of industry.The paper then investigates the impact and effects the digital economy has had on the economic growth of the three main sectors of industry in China's eastern,central,and western regions.Finally,the paper investigates the most significant differences among the various regions and the threshold effects of urbanization levels on the relationship between the digital economy and economic growth.The findings indicate a significantly positive correlation between the digital economy and regional economic growth.Moreover,geographical factors notably influence this correlation.The digital economy exerts a positive effect on all sectors of industry.It may not substantially impact industrial development in regions with highly developed infrastructure.Regarding the other regions,the digital economy exhibits varying degrees of impact due to the differences in the specific indicators.The conclusion drawn by the threshold model is that the magnitude of the threshold effect correlates with geographic factors.No threshold effect was observed in the eastern region,while the threshold effect occurred in the central region when the urbanization levels for the provinces were below 0.6645.Similarly,the threshold effect was noted in the western region when the urbanization level was below 0.3931.Considering all of this,the study also offers policy recommendations that will help balance the regional development of digital economies,accelerate the digital transformation of traditional industries,enhance digital infrastructure construction,refine the formulation and implementation of data policy,and establish relevant incentive mechanisms.

The Implications of Urbanization Processes in Developed Countries for Africa

Urbanization is the inevitable path of national economic development,and the level of urbanization development in most African countries is still low.By analyzing five typical developed countries in the United States,Britain,France,Germany,and Japan,this paper discusses the promoting factors and problems of the rapid urbanization development in their specific years,as well as the experiences and lessons that Africa can learn,so as to prevent Africa from taking the detour in the urbanization process of Western developed countries and promote the balanced regional development of various African countries.

Recent urbanization increases exposure to humid-heat extreme events over populated regions of China

目前对于高温的研究主要侧重于干热,针对湿热的研究相对较少,但它通常会造成更大的社会影响,尤其对人体健康的威胁.已有研究证实,当环境湿球温度超过35℃时,它会破坏人体正常生理代谢,进而威胁人体健康.本研究指出在过去四十年,中国区域日最高湿球温度几乎没有超过35℃,但部分地区日最高湿球温度超过了30℃,主要集中在中国的人口密集区,包括华东,华南和四川盆地等.进一步分析发现,中国区域近期的快速城市化加剧了极端湿热事件的社会影响,城市地区暴露于极端湿热事件的范围的增加速率明显大于其他地区,这也意味着快速城市化使得人口密集区暴露于极端湿热事件的风险明显增加.初步估算指出,自2000年以来,中国区域暴露于极端湿热事件的人口数以每年每天约3100人次的速率显著增加.

Effects of Urbanization on the Quantity Changes of Microbes in Urban-to-rural Gradient Forest Soil

Three typical rural-suburban-urban artificial wetlands Pinus elliottii forest in Nanchang City were selected as research objects to mensurate the soil nutrient content.And the annual average values and seasonal changes of microbes in forest soil were analyzed.The results showed that soil bulk density,total phosphorus （TP） and pH increased,while soil organic carbon （SOC）,total nitrogen （TN） declined with rural-to-urban gradient.At different eco-boundary,annual average values showed that actinomycetes quantity bacteria quantity fungi quantity.Total microbe number was urban suburb rural areas.The number of bacteria and fungi was urban suburbs rural areas,but the number of actinomycetes was suburb urban rural areas.Eco-boundary,season and microbes actinomycetes and fungi reached an extreme significant level （P 0.001）.Bacteria in soil at different eco-boundary had significant effects,but season had no significant effect on bacteria.Eco-boundary and season had a very significant interaction on actinomycetes and fungi （P 0.001）,but they had no significant interaction on bacteria （P 0.05）.Eco-boundary showed significantly positive correlation with actinomycetes and fungi （P 0.001）,but season had no significant corelation with microbes.In conclusion,urbanization process caused the physical-chemical properties changes of forest soil and affected the amount of soil microbes obviously.

Study on the Urbanization-based Restructuring of Urban Spaces in Meizhou City of China

By introducing the urbanization history of Meizhou City,major problems of its spatial structure were summarized as small scale of urban areas and incomplete hierarchical structure;poor cohesive force of central city,imbalanced regional spatial ratio;disorderly development of urban spaces;and fierce competition for space.Then spatial restructuring of Meizhou City was discussed from the following 3 perspectives:optimizing hierarchical structure of space,planning in advance to construct a central city with more than 1 million residents;establishing the traffic hub of Guangdong,Fujian and Jiangxi;improving spatial structure of industries.It was to enhance sustainable social and economic development of the local area,break the dualistic structure and realize the overall development of urban and rural areas,and also narrow the urban-rural gap.

Urbanization Level Analysis of Chongqing 1 Hour Economic Circle Based on AHP and GIS

With Chongqing 1 Hour Economic Center as an example, AHP was adopted to comprehensively analyze factors influencing the economic development of all districts and counties of Chongqing City, economic development scores were calculated and urbanization level of each district and county was comparatively analyzed. The results showed that the economic development level and the urbanization level of almost all districts and counties were not coordinated, then the reasons were briefly elaborated and corresponding countermeasures and suggestions were proposed.

Integration and Symbiosis between Traditional Folk Culture and Urban Space during Urbanization in China

By taking the residential environment change in Tai'an City of Shandong Province over the past 30 years for example, the paper had introduced characteristics of traditional residential culture and their influence on the urban residential spatial pattern, and explained the mutual effect and guidance between the establishment of new residential concepts and the extension of city context. It had pointed out that the government planning and development should be considered from historical and cultural perspective rather than economic perspective. Through the analysis of problems at each level, it had proposed that urban construction should pay attention to historical inheritance, and characteristic livable city construction should lay stress on the coordinated development between urban economy and historical culture.

Analysis of the Response and Driving Forces of Urban Landscape Pattern during Urbanization of Zhangjiagang City in China

By taking Zhangjiagang City as the research object, with the guidance of 3S (GIS, GPS and RS) and the theory of landscape ecology, based on the remote sensing images from 1991 to 2006, land use maps and social-economic statistical data, by combining with gradient analytical method, eight landscape pattern metrics had been selected to analyze the urbanization of Zhangjiagang City and urban landscape pattern change characteristics at different stages of urbanization. The results showed that the urbanization of Zhangjiagang City could be divided into two stages which were the urbanization of Zhangjiagang City from 1991 to 2001 and the suburbanization of Zhangjiagang City from 2001 to 2006 based on landscape metrics' change characteristics. During urbanization, the response was obvious in the urban center of Zhangjiagang City, and urban landscape pattern changed greatly. During suburbanization, the response was obvious in the rural area of Zhangjiagang City and rural landscape pattern changed greatly. The urbanization of Zhangjiagang City conformed to the urbanization mode based on population theory and extension theory. Urbanization firstly affected the urban center, and then extended to its surrounding areas, and further influenced widespread rural areas. During suburbanization, agricultural land had decreased and been seriously destroyed; thus, it should strengthen the protection of agricultural land.

Patterns of species diversity and functional diversity of breeding birds in Hangzhou across an urbanization gradient

Given the rapid rise in human population and increasing urbanization,it is important to understand their potential impacts on biodiversity.From March 2007 to August 2007,we conducted bird surveys in 90 strip transects,each 3 km long and 100 m wide,along a gradient of urbanization in Hangzhou,China.This gradient spanned a range of urbanization levels including urban areas,rural-urban continuum areas,farming areas,mixed forest/farming areas and forested areas.We recorded 96 breeding bird species and classified them into nine functional groups based on nesting requirements.The nine functional groups consisted of canopy nesters,shrub nesters,canopy/shrub nesters,natural cavity nesters,building nesters,natural cavity/building nesters,ground nesters,water surface nesters and parasitic nesters.Species and functional diversities were estimated based on the Shannon-Wiener index.Environmental data of each transect as human disturbance,vegetation cover and building index were also measured,and a synthetic urbanization index of each transect was introduced based on these data.We used regression analyses to model the relationship of species abundance,species diversity,functional abundance and functional diversity with this synthetic index.The results show that urbanization significantly reduces species richness,species diversity,functional richness and functional diversity,but the specific patterns differed.The relationship between species abundance/species diversity and urbanization is linear.In contrast,the relationship between functional diversity and urbanization was quadratic.In other words,with increased urbanization,functional diversity declined only slightly at first but then dropped at an accelerating rate.This implies that,although moderate urbanization reduces species diversity of breeding birds,it affects functional diversity of breeding birds only slightly in Hangzhou.The regression analysis of species diversity and functional diversity suggests a quadratic relationship between species diversity and functional diversity,i.e.,a linear relationship between species diversity and functional diversity can only exist at low diversity levels across urbanization gradients and increasing species abundance does not lead to an increase in functional diversity at the highest diversity levels.

Development Mode for the Characteristic Urbanization of Rural Areas in Heilongjiang Province

By analyzing the urbanization of rural areas in Heilongjiang Province,the authors pointed out the existing problems:insufficient motive power of its subjects,low construction level,less prominent functional features of townlets,low scale merits,low efficiency of resource distribution and so on.According to the classification of its townlets,the following 4 modes were given for the rural urbanization of Heilongjiang:A.Motivated by Ecological Construction.It is to solve population problems through ecological migrants,enhance infrastructure construction of townlets,strengthen their capacity of concentrating and absorbing resources;B.Motivated by featured agriculture.It is to develop featured industries on the basis of featured resources with market as the orientation,create a favorable exterior development environment for featured agriculture with the help of government;C.Based on Competitive Tourist Products.It is to coordinate the development of tourism and townlets through scientific planning,design competitive tourism projects and build famous tourism towns;D.Driven by Trade and Processing Industry.It is to promote the capacity of these towns in developing foreign trade,improve policy environment and trade facilities.All these 4 modes are proposed on the basis of actual conditions to give more choices for the characteristic urbanization of its rural areas.

Spatial Pattern and Process of Urbanization in Karst Area——A Case Study in Guiyang City

ObjectiveKarst area is one of ecological fragile regions in China, where the economic and social development is lagged heavily. In recent years, with the constant development of the west regions, economy and society are developed rapidly and urbanization speed is accelerated. This study aims to investigate the spatial pattern and process of urbanization in karst area of Guiyang City, which has important significance for land management and urban planning in karst area. MethodBased on RS and GIS technologies, TM satellite images in 1986, 1995 and 2000 and CBERS-01 satellite image in 2006 were adopted to obtain the data of urban land utilization in Guiyang City in the four years. The spatial pattern and process of urbanization in Guiyang City were investigated using urbanization proportion index （UPI）, urbanization intensity index （UII） and absolute expansion intensity （AEI）. ResultThe urbanization process in Guiyang City was significant, exhibiting polygon-urbanization, line-urbanization and point-urbanization. From the perspective of spatial pattern, the urbanization in Guiyang City displayed the cluster development; from the perspective of urbanization process, the urbanization speed in some secondary central areas was higher than that of central areas. ConclusionThe spatial pattern and process of urbanization in karst area were unique and were mainly influenced by terrain, transportation, economy, society and so on.

Research on Budding "Villages in Cities" during Urbanization Process in Lanzhou City of China——A Case Study of Chaijiahe Village,China

By introducing the theory of suburb urbanization,it was considered that budding villages in cities emerged with the close relation between city and suburb during rapid urbanization process.The paper had briefly analyzed development of villages in cities in China.By taking villages in Lanzhou City for example,it had studied geological location,appearance,spatial structure,economy and demographic feature of budding villages in cities.Furthermore,with Chaijiahe Village of Xiguoyuan Town as case study,empirical study had been conducted and development thought of Chaijiahe Village as budding village in city had been discussed.It emphasized that it should control the development scale of villages,economically and intensively utilize lands;develop industrialized high-efficiency agriculture and leisure agriculture,develop lily economy and explore the potential of characteristic industries;realize integration of urban and rural development;strive to develop education,improve villages' quality and cultivate villagers of new generation who possessed pioneering spirit and modern agriculture technology.On this basis,it summarized approaches to realize sustainable development of budding villages in cities.

Effect of urbanization on the abundance and distribution of Tree Sparrows (Passer montanus) in Beijing

With rapid urbanization occurring throughout China,the existence of Tree Sparrows (Passer montanus) in big cities is likely to be affected by a decrease in habitat and food availability.Can the urban Tree Sparrow adapt to these changes? To elucidate this question,we studied the effect of urbanization on the abundance and distribution of Tree Sparrows in Beijing.We found the abundance of the Tree Sparrow negatively correlated with an urbanization score.Sparrow abundance was very low in residential areas with high-rise buildings,commercial centers and main roads,while their numbers were significantly higher in parks,university campuses,low building residential and suburban areas.Environmental factors within the 50 m and 200 m scales were most suitable in predicting the distribution of Tree Sparrows during winter,while factors within 50 m and 400 m scales are suitable during the breeding season.During winter,the number of conifer trees and pedestrians were the major factors at the 50 m scale,while the area of high-rise buildings and vegetation become the predominant factors on a 200 m scale.Alternatively,during the breeding season the area of low buildings and the number of conifers and pedestrians were the main factors on the 50 m scale while the area of high-rise buildings and vegetation remained the most important factors on the 400 m scale.These results indicate that highly urbanized areas are not suitable habitats for the Tree Sparrow,although this species can adapt to human environments.Food and nest sites for urban birds should be considered in urban planning of big cities in developing countries.

China’s Urbanization Process and Outlook~

Starting JPom a low level China＇s rapid urOamzatlon ttas talcen on a targe scale over the past three decades. The urbanization of urban clusters has become a key driver of China＇s economic development. However, China＇s urbanization has been confronted with many issues, such as high resource and environmental costs, low level of citizenship for migrant workers, strong economic polarization and excessive dependence on land encroachment. In the near future, China＇s urbanization will enter a period of strategic transitioning, and the enhancement of the quality of urbanization will become a strategic priority. China＇s urbanization rate is projected to reach 60% by 2020 and 68% by 2030, eventually exceeding 80% by 2050. China＇s future urbanization must proceed from local realities, promote the balanced development of small, medium-sized and large cities and towns, optimize the spatial layout of urbanization, and follow a sensible pattern.

基于手机信令数据的广州市居民公园访问行为空间分异及其影响因素分析

加快推进城市公园建设是实现人与自然和谐共生的重要抓手。既有研究大多基于问卷调查数据和访谈资料分析城市居民的公园访问行为空间分异特征,研究结论的普适性和科学性有限。手机信令数据具有大样本、覆盖范围广、信息被动提供和动态实时性强等优点。利用手机信令数据精准刻画城市居民的公园访问行为,有助于开展城市公园的布局优化与品质提升工作。基于个体尺度的手机信令数据,本研究试图揭示广州市居民公园访问行为的空间分异特征并识别其影响因素,尤其关注城区居民和郊区居民的差别。结果表明:(1)城区居民的公园访问频率、公园访问时长和公园访问强度均高于郊区居民,前者的公园平均访问距离低于后者;(2)公园访问频率、公园访问强度、公园平均逗留时间和公园平均访问距离呈现高值集聚区/低值集聚区在城区连片分布,在郊区零星分布的空间特征;(3)公园访问行为受性别、年龄、时空约束性、社会经济地位、公园可达性、社区出行便利性和出行适宜性等因素的共同影响。本研究为相关政府部门精准开展城市公园的规划、建设与管理工作提供决策参考。