Evolution and Simulation of Spatial-temporal Heterogeneities in Ecological Background Quality of Changsha City

By GIS and ENVI,TM/ETM remote sensing images of five districts(Yuelu District,Furong District,Yuhua District,Tianxin District and Kaifu District) in Changsha City center in 2005,2010 and 2015 were interpreted.Moreover,distribution chart for ecological background factors in 2020 was simulated by using CA-Markov module in IDRISI.Using principal component analysis,evaluation model for ecological background quality of the city was established.Via circle analysi s,GS+semi variance function analysis,hot spot area analysis and grey correlation analysis,integrated analysis and evaluation on spatial heterogeneity evolution of ecological background quality in research region were conducted.Results showed that firstly Changsha overall has formed ecological pattern of landscape island city,but ecological background started to show the evolution trend of high heterogeneity and fragmentation under the construction land expansion,and ecological background quality of the city declined from 0.300,6 to 0.257,1 during 2005-2020.Secondly,ecological background quality of Changsha City had typical circle and axial gradient structure,and "eco tone" had the most violent evolution.Thirdly,spatial structure of ecological background quality had region,time and direction heterogeneities,and spatial heterogeneity of region was the most important.Fourthly,hot spot area distribution of ecological background quality evolution showed the "frog jump" trend of gathering in marginal zone and diffusing to peripheral zone.Fifthly,in driving factors of ecological background quality,industrialization rate had the highest grey correlation degree(0.842,1),and grey absolute correlation degree between ecological background quality in Yuelu District and industrialization rate was the highest(0.603,1).

Uncertainty evaluation of the coordinated development of urban human settlement environment and economy in Changsha city

The coordinated development of human settlement environment and economy is of vital significance to urban sustainable development and urban ecosystem health. Urban human settlement and economic systems exist in urban ecosystems, which are a structural complexity. Therefore the research is being challenged by some uncertain factors between human settlements and economic systems. However most of the researches were focused on its determinate objective aspects and qualitative analyses while less concern on the quanti- tative evaluation of coordinated development of urban human settlement environment and economy, especially little on its uncertain aspect. At present, the urgent task is to study the coordinated development of urban settlement environment and economy in terms of the effect of uncertainty. This study analyzed the uncertain characteristics, which would be confronted at different stages, such as confirming the index categories, their bound values, and their construction rate, etc. According to the actual urban conditions, many construction principles based on uncertainties are put forward and an indicating system for human settlement and economic evaluation is established. Moreover, the application of fuzzy mathematics presents a new method and a calculation model for the comprehensive assessment of the coordinated development of urban human settlement environment and economy. The application of the method and model in Changsha city of China showed that the assessment results can reflect not only the overall coordination degree of the city, but also the mode of interactive mechanism between urban economic system and human settlement environment.

Effect of human settlements on urban thermal environment and factor analysis based on multi-source data:A case study of Changsha city

In view of the lack of comprehensive evaluation and analysis from the combination of natural and human multi-dimensional factors,the urban surface temperature patterns of Changsha in 2000,2009 and 2016 are retrieved based on multi-source spatial data(Landsat 5 and Landsat 8 satellite image data,POI spatial big data,digital elevation model,etc.),and 12 natural and human factors closely related to urban thermal environment are quickly obtained.The standard deviation ellipse and spatial principal component analysis(PCA)methods are used to analyze the effect of urban human residential thermal environment and its influencing factors.The results showed that the heat island area increased by 547 km~2 and the maximum surface temperature difference reached 10.1℃during the period 2000–2016.The spatial distribution of urban heat island was mainly concentrated in urban built-up areas,such as industrial and commercial agglomerations and densely populated urban centers.The spatial distribution pattern of heat island is gradually decreasing from the urban center to the suburbs.There were multiple high-temperature centers,such as Wuyi square business circle,Xingsha economic and technological development zone in Changsha County,Wangcheng industrial zone,Yuelu industrial agglomeration,and Tianxin industrial zone.From 2000 to 2016,the main axis of spatial development of heat island remained in the northeast-southwest direction.The center of gravity of heat island shifted 2.7 km to the southwest with the deflection angle of 54.9°in 2000–2009.The center of gravity of heat island shifted to the northeast by 4.8 km with the deflection angle of 60.9°in 2009–2016.On the whole,the change of spatial pattern of thermal environment in Changsha was related to the change of urban construction intensity.Through the PCA method,it was concluded that landscape pattern,urban construction intensity and topographic landforms were the main factors affecting the spatial pattern of urban thermal environment of Changsha.The promotion effect of human factors on the formation of heat island effect was obviously greater than that of natural factors.The temperature would rise by 0.293℃under the synthetic effect of human and natural factors.Due to the complexity of factors influencing the urban thermal environment of human settlements,the utilization of multi-source data could help to reveal the spatial pattern and evolution law of urban thermal environment,deepen the understanding of the causes of urban heat island effect,and clarify the correlation between human and natural factors,so as to provide scientific supports for the improvement of the quality of urban human settlements.

Epidemiologic survey and analysis of mild cognitive impairment amongst community senior citizens of Changsha City

Objective:The purpose of the current study was to conduct a mild cognitive impairment(MCI)prevalence survey among the community senior citizens of Changsha City and analyze possible relevant factors so as to perform early screening and intervention for MCI patients,and delay or prevent MCI from developing into Alzheimer’s disease(AD).Methods:Between April and September 2012,a total of 1764 community senior citizens in Changsha City were selected through multi-stage and random cluster sampling as study subjects.The following tables were used during the investigation to perform preliminary MCI screening for the subjects of this study:a general information survey;Mini-Mental State examination(MMSe);Montreal Cognitive Assessment(MoCA);Beijing version;global Deteriorate Scale(gDS);Clinical Dementia Rating(CDR)scale;and Activities of Daily Living(ADL)scale.Then,neurology specialists made diagnoses according to the actual status of subjects,survey findings,and clinical MCI diagnostic standards.The prevalence of MCI was calculated and the rates concerning senior citizens with different demographic characteristics were compared.Logistic regression analysis was used to analyze relevant factors that led to MCI,and comparing findings with those of other cities was conducted.Results:The MCI prevalence among senior citizens in Changsha City was 16.27%(287/1764).The MCI prevalence increased with age[for the 60,70,and 80 age groups,the prevalence was 9.79%(84/858),20.14%(149/740),and 32.53%(54/166),respectively,P<0.05].The more education received,the less the likelihood of developing MCI[the prevalence of illiteracy,those who went to pri-mary school,junior high school,senior high school,or technical secondary school,college,and un-dergraduates and above was 32.10%(26/81),18.40%(90/489),13.97%(70/501),15.29%(61/399),14.39%(19/132),and 12.96%(21/162),respectively,P<0.05].Bluecollar workers’chances of developing MCI was higher than white-collar workers[19.12%(187/978)and 12.72%(100/786),respectively,P<0.05].Living alone increased the likelihood of developing MCI than not living alone[21.59%(65/301)and 15.17%(222/1463),P<0.05].The logistic regression analysis showed that age,educational background,and marital status were in the regression(P<0.05).The MCI prevalence of Changsha did not differ from that Portugal,Singapore,Beijing,and Urumchi(P>0.05),but lower than Shanghai[35.78%(161/450)]and higher than Chengdu[2.35%(92/3910)](P<0.05).Conclusion:The prevalence of MCI among the community senior citizens of Changsha City is highly related to factors like age,educational background,and marital status.Prevention against these highrisk factors shall be carried out to delay cognitive decline for senior citizens.

化冰盐对灾后长沙城市森林植物的危害

2008年1月中旬至2月初,50年以来罕见的严重冰冻灾害,对长沙城市森林植物损害巨大[1]。抗冰救灾期间,为保交通,对市区范围"6纵15横"共21条主干道进行撒盐融冰,据有关部门统计,至2月4日,累计抛撒工业用盐近7000t,日均撒盐量达600t[2-3]。大量使用工业盐或氯盐类融雪剂化冰,对桥梁、公路及植物等产生的次生灾害国内外己有深刻的教训。为此,我们对长沙市主干道绿化带进行了跟踪调查,发现目前大面积花灌木死亡或生长不良的主要原因除遭受严重冻害之外,渗入绿化带土壤中的盐分已使土壤出现不同程度的盐碱化,对适宜酸性土生长的本土植物构成了不可低估的生态灾害。本文旨在为长沙城市森林灾后重建工作提出解决途径。

长沙城市森林树种冰冻灾害的调查与反思

2008年1月中旬至2月初,湖南遭遇50年以来罕见的严重冰冻灾害,大面积交通受阻,供电中断,给全省人民的生产生活带来严重影响。持续了20多天的冰冻,对长沙城市森林损害巨大,大量木竹倒伏、折枝、断干、翻蔸,其中栽植密度较大的景观林、生态林和湿地松、火炬松、桉树、香樟、桂花、广玉兰、毛竹、观赏竹类等常绿树种及古树名木受冰冻雪压尤为严重。通过对灾情的调查与反思,提出在我国南方城市森林建设中,要加强抗灾预警机制的建设,要重视选用抗冰冻雪压性能强的乡土树种。