Exploring spatio-temporal variations of habitat loss and its causal factors in the Shenzhen River cross-border watershed     

《Applied geography (Sevenoaks, England)》2013

Understanding the mechanisms that underlie habitat loss is fundamental to nature conservation. Habitat loss and its related factors are location dependent, but their spatial variations across geographical space are poorly understood. This research attempts to explore the spatio-temporal variations of human and biophysical factors of habitat loss in the Shenzhen River watershed, a border region shared by the Hong Kong Special Administrative Region (SAR) and Shenzhen in China. Habitat loss was quantified through the comparison of historical land cover maps in 1988/1998/2008, derived from the Landsat imagery. The different degree of habitat loss is further considered by referring to loss of ecosystem services during habitat alteration or destruction processes. In order to examine how influencing factors change with space, the model of geographically weighted regression (GWR) was employed. The GWR model was proved to be effective in revealing a spatially varying relationship, and has better performance compared with the global regression model. The results also provided the detailed site information of the different roles of the related factors across the different locations. Various factors, especially the human-related ones, played a significant role in determining both the “rate” and “location” of habitat loss, and the influences also varied during the entire study period. These results could provide comprehensive information for future habitat conservation and cross-border watershed management.  相似文献   

Physical and biological development of a newly breached managed realignment site,Humber estuary,UK     

《Marine pollution bulletin》2008,56(10-12):564-578

As part of the Humber flood defence upgrade works (Urgent works) undertaken by the Environment Agency, the Paull Holme Strays site was identified as one of twelve potential managed realignment sites within the Humber catchment. The site was breached in September 2003, creating 80 hectares of new intertidal habitat. Initial accretion monitoring commenced in December 2003 with annual surveys of invertebrate colonisation commencing in October 2004. The present study gives details of the physical development of the newly created mudflat within the site, together with invertebrate colonisation and benthic community change over time. Comparisons between the newly created habitat and the existing mudflat outside the old sea wall are made.The macrofaunal communities found within the area as a whole are considered to be characteristic of the area with low species diversity, high abundance and small body size. The community within the managed realignment site is still in an early successional stage with low abundance and diversity in comparison with other sites within this part of the Humber. However the community biomass increased considerably between 2004 and 2005. Colonisation within the managed realignment site is still primarily concentrated in the areas around the two breach sites and is thought to be restricted in other areas due to infrequent tidal inundation.  相似文献   

A combined luminescence and radiocarbon dating study of the Ili loess,Central Asia     

《Quaternary Geochronology》2012

Similar to the loess in the Chinese Loess Plateau (CLP), the loess deposits in the Ili basin of Central Asia arid area play an important role in understanding the climate and environmental changes. However, in contrast to the intensively investigated loess deposits in the CLP, the Ili loess is still insufficiently known and poorly understood. The geochronology study of the Ili loess remains controversial. In order to examine the potential of optically stimulated luminescence (OSL) dating for the Ili loess, we carry out a combined luminescence and radiocarbon dating study on a 6.9 m loess section in the south margin of the Ili basin. Polymineral fine grains were investigated by post infrared (IR) OSL using a Multiple-Aliquot Regenerative-dose (MAR) protocol. Radiocarbon dating of organic carbon were carried in a 3 Megavolt (MV) multi-element Accelerator Mass Spectrometry (AMS). The results indicate that the OSL ages are in agreement with the observed stratigraphy in the field, which is well correlated with that of the CLP, but the AMS ¹⁴C ages are much younger than the OSL and assumed stratigraphical ages. Thus, the OSL dating technique may provide an absolute chronology in this loess section. Further methodological approaches and more samples analysis will lead to the improvement of this chronology for high-resolution paleoclimatic interpretation.  相似文献   

Comparative dating of recent peat deposits using natural and anthropogenic fallout radionuclides and Spheroidal Carbonaceous Particles (SCPs) at a local and landscape scale     

《Quaternary Geochronology》2013

Proxy records from recently accumulated peats provide valuable information about past environmental change, but they depend on high quality chronological information to calculate rates and timing of change. However, there is uncertainty in the accuracy and consistency of the methodologies used for dating recent peats. This study compares results from Spheroidal Carbonaceous Particles (SCPs) and natural and anthropogenic fallout radionuclides (²¹⁰Pb, ¹³⁷Cs and ²⁴¹Am) used to date three replicate cores from three contrasting sites. Data are used to test the consistency of dating techniques within and between sites, and to assess the impact of local conditions on geochronological results.There is broad consistency in results, but there is also a significant disagreement between dates in a number of cores, both within and between sites. A relatively dry site that had been affected by past burning and erosion showed the greatest consistency between methods and replicate cores. Wetter, less degraded sites showed least consistency. Using patterns of (dis)agreement between dating techniques we assess the potential causes of dating inaccuracy. The data support previous suggestions that ²¹⁰Pb is mobile in wetter conditions, and suggests that ²⁴¹Am can be considered an increasingly valuable radionuclide. Finally, our data suggest the current estimates for SCP-based ages in the region maybe incorrect and require further regional calibration.Using several techniques on replicate cores from three sites in the same area has provided a more robust evaluation of the likely reliability of individual techniques and the processes that may adversely affect them. We conclude that until advances are made in understanding the processes behind the variable quality of SCP and fallout radionuclide dating, using two or more dating techniques will greatly improve understanding of the validity of a peatland chronology, especially in wetter locations.  相似文献   

Shift-share Analysis on International Tourism Competitiveness - A Case of Jiangsu Province   总被引：5，自引：0，他引：5  

SHI Chunyun ZHANG Jie YANG Yang ZHOU Zhang 《中国地理科学(英文版)》2007,17(2):173-178

Shift-share analysis has been confirmed a useful approach in the study of regional economics and many kinds of extended shift-share models have been advanced and put into practice in economic studies, but few have hitherto been introduced and applied to the tourism research in China. Moreover understanding the spatially competitive relationship is of paramount importance for marketers, developers, and planners involved in tourism strategy development. Based on international tourism receipts from 1995 to 2004, this study aims at probing into the spatial competitiveness of interna- tional tourism in Jiangsu Province in comparison with its neighbors by applying a spatially extended shift-share model and a modified dynamic shift-share model. The empirical results illustrate that exceptional years may exist in the ap- plication of dynamic shift-share models. To solve this issue, modifications to dynamic shift-share model are put forward. The analytical results are not only presented but also explained by the comparison of background conditions of tourism development between Jiangsu and its key competitors. The conclusions can be drawn that the growth of international tourism receipts in Jiangsu mainly attributes to the national component and the competitive component and Zhejiang is the most important rival to Jiangsu during the period of 1995-2004. In order to upgrade the tourism competitiveness, it is indispensable for Jiangsu to take proper positioning, promoting and marketing strategies and to cooperate and integrate with its main rivals.  相似文献   

Evaluating the role of climate and tectonics during non-steady incision of the Yellow River: evidence from a 1.24 Ma terrace record near Lanzhou,China     

Baotian Pan  Huai Su  Zhenbo Hu  Xiaofei Hu  Hongshan Gao  Jijun Li  Eric Kirby 《Quaternary Science Reviews》2009,28(27-28):3281-3290

The competing roles of bedrock uplift and climatic change in the formation of fluvial terraces remain uncertain. Most of recent studies have attributed terrace formation to climatic changes and held that, even in tectonically active settings, climate variations control cycles of terrace planation and abandonment. Based on field investigations of loess-paleosol sequences, magnetostratigraphy and optically stimulated luminescence (OSL) dating, we develop a new chronology for a spectacular flight of terraces along the Yellow River near Lanzhou, China over past 1.24 Ma. All the terraces are strikingly similar in that they have several meters of paleosol developed directly above fluvial deposits on the terrace treads, suggesting that the abandonment of each terrace due to river incision occurs during the transition from glacial to interglacial climates. However, the ages of terraces cluster in two relatively short time periods (1.24–0.86 Ma and 0.13 Ma – present). During the intervening time between 0.86 Ma and 0.13 Ma, terraces either did not form or were not preserved. We suggest that this record indicates that rock uplift rates varied through time and influenced terrace formation/preservation. Thus, our results demonstrate the utility of deep chronologic records from fluvial terraces for deconvolving the effects of tectonics and climate on fluvial incision.  相似文献   

Measurement and Scenario Simulation of Effect of Urbanisation on Regional CO₂ Emissions Based on UEC-SD Model:A Case Study in Liaoning Province,China     

LI Fujia  DONG Suocheng  LI Shantong  LI Zehong  LI Yu 《中国地理科学(英文版)》2015,(3):350-360

Based on the logical causal relationship and taking Liaoning Province, China, which is the Chinese traditional industrial base and is in the stage of accelerated urbanisation, as a case study, this study builds the ′Urbanisation-Energy Consumption-CO2 Emissions System Dynamics(UEC-SD)′ model using a system dynamics method. The UEC-SD model is applied to analyse the effect of the urbanisation process on the regional energy structure and CO2 emissions, followed by simulation of future production and living energy consumption structure as well as the evolutionary trend of CO2 emissions of three urbanisation scenarios(low speed, intermediate speed and high speed) under the assumed boundary conditions in urban and rural areas of Liaoning Province, China. The results show that the urbanisation process can alter production and the living energy consumption structure and thereby change regional CO2 emissions. An increase in the urbanisation rate in case area will lead to regional CO2 emissions rising in the short term, but when the urbanisation rate approaches 80%, CO2 emissions will reach a peak value and then decrease. Comparison of different urbanisation rates showed that production and living energy consumption exhibit different directions of change and rules in urban and rural areas. The effect of urbanisation on CO2 emissions and energy structure is not direct, and urbanisation can increase the differences in energy and CO2 emissions between urban and rural areas caused by the industrial structure, technical level and other factors.  相似文献   

菲律宾海北部四国海盆全新世沉积物源分析     

韩卓尘  高抒  李艳平 《海洋学报》2015,37(2):11-24

对IODP333航次四国海盆北部地区C0011站位表层样品进行粒度和Sr-Nd同位素分析,并与前人发表的邻近海域同位素数据进行比较。经分离自生碳酸盐组分,四国海盆全新世沉积物呈现较好的陆源、火山源二端元组分特征。从地理位置看,四国海盆北部主要物质来源包括伊豆-小笠原海脊火山物质、日本列岛西南部的混合型沉积物以及由西向风或河流入海洋流输送而来的亚洲陆地沉积物,且日本列岛西南部对于该区域物质贡献最大。对四国海盆北部而言,与海盆中部沉积及日本海沉积相比,源自亚洲大陆的碎屑沉积物具有更多的贡献。沉积物中87Sr/86Sr与εNd、平均粒径的负相关关系反映了沉积物中陆源物质的相对贡献按时间顺序呈现增加、减小、增加、减少的多周期变化趋势。  相似文献   

基于TileStache的多源投影矢量数据瓦片生成技术研究   总被引：1，自引：0，他引：1  

王亚平  蒲英霞  刘大伟  宋雪涛 《地理信息世界》2015,(1):77-81

瓦片技术的出现改变了传统Web GIS的服务架构,提高了地图数据请求响应的效率。针对多种地图投影类型或地理坐标的矢量数据在瓦片划分过程中遇到的问题,本文基于OGR地理数据模型,设计了多投影数据转换Python模块,扩展至开源应用程序Tile Stache,得到适用于多源投影矢量地理数据的瓦片生成工具OTile Tool;从而实现矢量地理数据瓦片的快速生成,为网络地理信息系统提供了表达地理信息的Geo JSON格式瓦片数据。  相似文献   

基于地面三维脉冲激光扫描技术的变形监测若干问题研究     

郭献涛 《测绘学报》2021,50(4):568-568

在传统大地测量中,变形监测为控制网中稀疏监测点观测所驱动。近年来,随着地面激光扫描(terrestrial laser scanning,TLS)技术的迅速发展,该技术显示出应用于变形监测的巨大潜力,尤其是在危险和人员难以到达的灾害监测领域。由于TLS扫描测点的不可重复性,传统基于离散点的监测模式不再适用。为此,亟须研究与TLS技术相适应的变形监测新模式与变形提取新方法。  相似文献