Modeling the effects of land-use optimization on the soil organic carbon sequestration potential   总被引：3，自引：2，他引：1  

Jingtao Yao  Xiangbin Kong 《地理学报(英文版)》2018,28(11):1641-1658

Increasing soil organic carbon (SOC) sequestration is not only an efficient method to address climate change problems but also a useful way to improve land productivity. It has been reported by many studies that land-use changes can significantly influence the sequestration of SOC. However, the SOC sequestration potential (SOCP, the difference between the saturation and the existing content of SOC) caused by land-use change, and the effects of land-use optimization on the SOCP are still not well understood. In this research, we modeled the effects of land-use optimization on SOCP in Beijing. We simulated three land-use optimization scenarios (uncontrolled scenario, scale control scenario, and spatial restriction scenario) and assessed their effects on SOCP. The total SOCP (0–20 cm) in Beijing in 2010 was estimated as 23.82 Tg C or 18.27 t C/ha. In the uncontrolled scenario, the built-up land area of Beijing would increase by 951 km² from 2010 to 2030, and the SOCP would decrease by 1.73 Tg C. In the scale control scenario, the built-up land area would decrease by 25 km² and the SOCP would increase by 0.07 Tg C from 2010 to 2030. Compared to the uncontrolled scenario, the SOCP in 2030 of Beijing would increase by 0.77 Tg C or 0.64 t C/ha in the spatial restriction scenario. This research provides evidence to guide planning authorities in conducting land-use optimization strategies and estimating their effects on the carbon sequestration function of land-use systems.  相似文献   

Flexible Spatial Multilevel Modeling of Neighborhood Satisfaction in Beijing     

Jing Ma  Yu Chen  Guanpeng Dong 《The Professional geographer》2018,70(1):11-21

This article develops an innovative and flexible Bayesian spatial multilevel model to examine the sociospatial variations in perceived neighborhood satisfaction, using a large-scale household satisfaction survey in Beijing. In particular, we investigate the impact of a variety of housing tenure types on neighborhood satisfaction, controlling for household and individual sociodemographic attributes and geographical contextual effects. The proposed methodology offers a flexible framework for modeling spatially clustered survey data widely used in social science research by explicitly accounting for spatial dependence and heterogeneity effects. The results show that neighborhood satisfaction is influenced by individual, locational, and contextual factors. Homeowners, except those of resettlement housing, tend to be more satisfied with their neighborhood environment than renters. Moreover, the impacts of housing tenure types on satisfaction vary significantly in different neighborhood contexts and spatial locations.  相似文献   

基于地理标记照片的北京市入境旅游流空间特征   总被引：11，自引：1，他引：10  

秦静  李郎平  唐鸣镝  孙岩  宋昕芮 《地理学报》2018,73(8):1556-1570

城市作为现代旅游目的地的一种重要类型,在集聚旅游发展要素、塑造城市休闲空间、提升城市品质等方面具有突出作用。城市旅游流是城市旅游要素关联、空间组织的路径,对于城市交通组织方式、公共服务设施建设、休闲旅游产业布局等方面影响越来越大。本文立足城市内部微观尺度,以入境旅游流空间特征为研究对象,利用数据挖掘技术,通过Flickr API接口获取了2004-2015年北京市范围内全部带有地理信息的照片及其属性信息,通过构建的数据清洗方法控制初始数据质量,建立基础数据库,使用密度聚类（P-DBSCAN）、马尔科夫随机链等方法探索入境游客热点区域空间分布格局、流动空间特征。结果显示：① 北京市历史城区（2环之内区域）、中心城区（2环至5环之间区域）以及郊区（5环之外区域）的旅游热点区域（AOI）呈现出不同的空间特征,其中历史城区AOI呈现出与景区、休闲娱乐、餐饮购物等相关产业空间重叠的趋势,各热点区域边界模糊,复合连绵成片。中心城区AOI集聚与城市功能区密切相关,具有明确的城市功能取向。郊区AOI基本与旅游景点一致,没有向景区外部延伸;② 传统历史文化类AOI访问热度占有绝对优势,商业购物休闲AOI及现代城市功能AOI的影响力在逐渐增强;③ 强入境旅游流主要集中在历史城区内部AOI之间,以及中心城区的西北部与东部区域内部AOI之间,郊区AOI之间没有较强的旅游流,北京市入境旅游流整体呈现以历史城区为中心,放射性分布的框架;④ 各区域AOI之间均有较次一级旅游流联系,北京市入境旅游流形成了初步的网络结构。  相似文献   

北京典型行业微区位选址比较研究——以北京企业管理服务业和汽车制造业为例   总被引：5，自引：2，他引：3  

李佳洺  孙威  张文忠 《地理研究》2018,37(12):2541-2553

以微观企业数据为基础,采用核密度空间平滑和条件逻辑选择模型等方法,重点关注企业在城市内部微观尺度下的区位选择,并对北京典型现代服务业和制造业区位选择的差异进行对比分析。结果表明：① 北京中小型制造企业倾向于在集聚区分布,符合马歇尔式产业集群的特征,而服务业则是大型企业更倾向于集中布局;② 尽管微观尺度下多样化和上下游产业链对现代服务业和制造业依然有重要影响,但是与宏观尺度下不同的是对于现代服务业来说过度多样化并不利于其发展,对于制造业来说区域专业化劳动力规模而非专业化程度更为重要;③ 政府对地铁等公共设施布局选址将对现代服务业的微观区位产生重要影响。  相似文献   

超大城市生产性服务业空间分工及其效应分析——以北京为例   总被引：1，自引：1，他引：0  

宋昌耀  罗心然  席强敏  李国平 《地理科学》2018,38(12):2040-2048

为探究超大城市生产性服务业空间分工机理及效应,基于2006~2015年北京各区数据和地区相对专业化指数等方法分析北京生产性服务业空间分工特征,研究发现,北京生产性服务业呈现从中心到外围专业化程度提升、多样化程度下降的趋势,且动态来看,专业化水平都有所提升,空间分工趋势愈加明显;高级生产性服务业集聚在多样化地区,交通运输业分散在专业化地区,房地产服务业是多数地区的专业化产业。空间面板计量模型检验表明,北京各区之间生产性服务业空间溢出效应明显,联动协调发展水平较高;生产性服务业各细分产业的空间分工效应与产业特性高度相关,交通服务业呈现负向空间溢出,金融、科技、信息、房地产等服务业存在正向溢出,而商务服务业溢出效应不显著。  相似文献   

北京2009~2013年期间持续性大雾的类型、垂直结构及物理成因   总被引：2，自引：0，他引：2  

郭丽君  郭学良 《大气科学》2016,40(2):296-310

北京地区持续性大雾天气近几年呈显著增加趋势,但由于缺乏高时间分辨率的雾微物理和大气廓线数据,限制了对大雾垂直结构和物理成因的深入了解。本文基于美国Radiometrics公司生产的35通道MP-3000A型微波辐射计廓线仪(Microwave Radiometer Profiler,简称MWRP)及常规气象和卫星观测资料分析研究了2009~2013年期间北京地区13次大雾天气过程的类型、垂直结构特征及其产生的物理成因。按照雾产生的基本条件,将13次大雾天气主要划为平流雾和蒸发雾两类,辐射雾存在于持续性大雾过程中,不做单独划分。平流雾的平均雾顶高度不超过1.0 km,而蒸发雾的平均雾顶高度在0.5~1.5 km之间。平流雾主要是由来自西南和东南的暖湿平流移经北京地区冷下垫面后冷却降温过程产生,强逆温的形成有利于雾的持续发展。而蒸发雾是由本地区降水蒸发冷却形成,或是冷平流移经暖湿下垫面形成。按照微波辐射计连续观测的雾宏微观垂直结构特征,将13次大雾天气过程又划分为单一雾结构和云雾共存结构,并采用卫星和地面气象观测数据对部分典型雾个例进行了比较验证研究。结果表明,在13次大雾天气中,平流雾和蒸发雾各占69%和31%。由此说明北京地区持续性大雾天气主要是由暖湿平流过程和降水蒸发冷却过程造成,与天气过程的异常密切相关。单一雾结构仅占15%,而云雾共存结构占近85%,且持续三天以上的大雾天气基本具有云雾共存结构。  相似文献   

The rise of venture capital centres in China: A spatial and network analysis     

《Geoforum》2016

Due to the importance of venture capital (VC) firms in spurring regional economic growth, the geography of VC firms and VC investments have attracted a lot of attention. However, the spatial patterns of cross-regional VC flows have rarely been explored, particularly in the context of emerging economies. Drawing on a unique dataset on VC firms and investments related to domestic initial public offerings (IPOs), this study combines location analysis with network analysis to investigate the spatial patterns of VC activities in China. The results confirm that Beijing, Shenzhen and Shanghai are the leading VC centres in the country. Although Yangtze Delta Area hosts the largest number of investments, Beijing and Shenzhen have a considerable advantage over Shanghai in terms of the number of VC firms, investments, and the number of domestic VC-backed IPOs. Beijing and Shenzhen also appear more central than Shanghai in China’s VC networks, with Beijing-Shenzhen representing the most important city-dyad in terms of VC investment flows. The article explains how the dynamics of the VC centres is embedded in China’s institutional and cultural context, critical to understanding the evolution and geography of China’s VC industry.  相似文献   

北京平原地区第四纪地质研究新进展   总被引：2，自引：1，他引：1       下载免费PDF全文

蔡向民  张磊  郭高轩  尤世娜  方同明  吕金波  梁亚楠 《中国地质》2016,(3):1055-1066

北京平原地处山前冲洪积扇分布区,区内湖泊密布,河流纵横,沉积环境多样。由于第四系三维结构的复杂性,对第四系进行地层划分有一定的难度。前人根据不同的资料对北京平原第四系进行过地层划分,建立了泥河湾组、周口店组、马兰组等多个岩石地层单位。这些地层单位主要是依据沉积凹陷钻孔岩心中的孢粉、有孔虫、介形虫等化石和少量的古地磁数据划分的,实际上仍是年代地层单位。由于这些地层单位划分依据不统一,识别标志不清晰,因此难以得到广泛的共识。近十余年来,随着资料的积累和对第四系三维结构的认识提高,特别是古地磁测年技术的普及,为北京平原第四纪地层的划分奠定了基础。本文依据40余个钻孔的古地磁测试数据,初步厘定了下更新统底界、中更新统底界、上更新统底界3个等时面。依据工程地质勘察、水文地质钻孔、考古发掘和泥炭调查等资料编绘了平原区全新统等厚度图。  相似文献   

北京地区太古宙变质地层研究新进展          下载免费PDF全文

方同明  孙永华  刘鸿  程新彬  吴虎峻  尤世娜  吕金波 《中国地质》2016,(3):890-898

北京北部山区密云—怀柔地区广泛分布太古宙变质岩。该区经历多期地质构造作用,矿产丰富,一直以来受到国内外地质学者的广泛关注。通过对北京密云—怀柔地区太古宙变质岩石和年代学深入系统的研究,变质建造、变质作用条件、变形变质和同位素年代学等方面研究,提出本区变质表壳岩新的划分方案,在区内变质地层研究方面取得了新的进展。  相似文献   

Discovery of Cosmic Spherules from the Mesoproterozoic Strata and its Significance—in Case of the Ming Tombs Area, Beijing     

SONG Tianrui  ZHENG Ning  LIU Yongqing  KUANG Hongwei  PENG Nan  LI Chao  TANG Jigang  YAN Qinggao  GAO Linzhi  ZHU Zhicai  XIA Xiaoxu  WANG Yuchong 《《地质学报》英文版》2020,94(1):38-56

This study covers cosmic spherules derived from the Mesoproterozoic Dahongyu Formation in the Ming Tombs area, Beijing. The cosmic spherules include iron oxide cosmic spherules, carbonaceous chondrites, and atomic iron “steely bead”-shaped cosmic spherules. The mineral assemblage of silicon carbide, forsterite, zircon, and glass spherules and fragments were picked from melt-silicified carbonate of the Mesoproterozoic Dahongyu Formation (ca. 1625 Ma). Cosmic spherule assemblages are solely discovered from sedimentary rocks in China. Platinum group elements (PGE) were determined for the first time in cosmic spherules and associated minerals. PGE comparative observation between meteorite and cosmic spherules is presented in this study. It is recognized that an extraterrestrial meteorite impact event might have occurred in the Dahongyu Stage. The main evidence is a large number of iron cosmic spherules in silicified oncolitic limestone, and associated cosmic silicon carbide, glass spherules, and fragments, as well as the presence of forsterite. The impact-volcanic crater is characteristic of a big black shale block dropped into the bended silicified limestone.  相似文献