Landscape Dynamics and Driving Factors in Da＇an County of Jilin Province in Northeast China During 1956-2000     

Zongming Wang  Yubo Zhang  Bai Zhang  Kaishan Song  Zhixing Guo  Dianwei Liu  Fang Li 《中国地理科学(英文版)》2008,18(2):137-145

The landscape pattern of Da＇an County, Northeast China has undergone significant changes since the 1950s as a result of climatic change and human activities. The aim of this paper is to quantitatively study landscape pattern and its spatial dynamics of Da＇an County at the landscape level over the nearly 50-year span. Patch dynamics were examined according to land use and land cover change processes built from a series of images, as well as topographic maps, and temporal patterns built from landscape pattern metrics. The transition matrix of landscape patch types and changes of various landscape metrics were applied. The results showed that, from 1956 to 2000, the landscape within the study area had undertaken a complicated evolution in landscape structure and composition. The outstanding characteristic is that saline-alkali land increased and grassland decreased. As some smaller patches amalgamated, the heterogeneity of patch decreased. All those changes were the synthetic result of both climatic and anthropogenic influences, but the predominant factor was different in different parts. In the southern part of the study area, the landscape pattern changes resulted from the modification of climate obviously, while in the northern part, the landscape pattern changes were mainly caused by human activities, such as the conversion between farmland and saline-alkali land. This phenomenon showed that human activities played more important role in the north than in the south of Da＇an County.  相似文献   

Contribution of a pathway through the Arctic Ocean to the re cent reduction in the ice cover     

Motoyoshi Ikeda 《极地研究(英文版)》2008,19(2):212-217

The sea ice cover in the Arctic Ocean has been reducing and hit the low record in the summer of 2007. The anomaly was extremely large in the Pacific sector. The sea level height in the Bering Sea vs. the Greenland Sea has been analyzed and compared with the current meter data through the Bering Strait. A recent peak existed as a consequence of atmospheric circulation and is considered to contribute to inflow of the Pacific Water into the Arctic Basin. The timing of the Pacific Water inflow matched with the sea ice reduction in the Pacific sector and suggests a significant increase in heat flux. This component should be included in the model prediction for answering the question when the Arctic sea ice becomes a seasonal ice cover.  相似文献   

Environmental evolution of Gongwang Mountains during Holocene in northeastern Yunnan, China     

Wei ZHANG  Chuanchuan LI  Zhijiu CUI  Jinliang FENG . College of Urban  Environmental Sciences  Liaoning Normal University  Dalian  Liaoning  China. College of Environmental Sciences  Peking University  Beijing  China 《东北亚地学研究》2008,11(3):156-167

This paper presents the study on two continuous glacio-lacustrine sedimentary deposits, Laotanfang （3 597 m） and Shibantang （3 689 m） located on the southern and northern sides of Hulifang peak in Yunan, China. Environmental change indexes are constructed for each deposit, based on grain size, geochemical and pollen analysis, environmental magnetic susceptibility, and 14C dating. The study of climatic environmental change since the Holocene epoch in this region shows that the climate fluctuated at different stages during the early Holocene, that is, the climate was cool and wet during 8.4-7. 7r ka, cold and wet during 7.7-6. 5 ka, cold and dry during 6. 5-4.7 ka, cool and wet during 4.7-2. 1 ka, warm and wet during 2. 1-1.0 ka, and warmer and wet since 1 ka. These findings reflect the overlapping influences of the southwest and southeast monsoons in different times during the Holocene in the north part of southwestern China are in accord with other Holocene climate change models in this part of China.  相似文献   

江苏省环太湖地区土地利用结构演变与驱动力分析   总被引：6，自引：0，他引：6  

李闽  孙在宏  杨素静  乔伟峰 《地球信息科学学报》2008,10(2):136-141

本文以江苏省环太湖地区为研究区域,以1996～2007年快速发展时期为研究时段,对这一特定时空的土地利用结构变化及其驱动机制进行研究。文章以大量数据为基础,分析了区域内土地利用结构动态度、信息熵和均衡度。1996年以来,江苏省环太湖地区用地结构调整即以趋向均衡的速度逐渐变缓。从2004年开始,江苏省环太湖地区用地结构趋向合理、均衡化发展。文章揭示了土地利用结构与经济发展驱动因素、农业集约化因素、城市化因素、人口因素、政策因素这五个因素有关。  相似文献   

基于持久化的网吧管理系统数据库设计和实现     

徐多勇  李志蜀 《成都信息工程学院学报》2008,23(3):239-243

设计了一种健壮持久层体系结构,并运用该结构,根据对象/关系数据库映射（O/R Mapping）策略,设计和实现了基于持久化的网吧管理系统数据库。这种实现数据持久化的方案在C＋＋开发环境下,具有比较重要的应用价值。  相似文献   

同步N-策略多重休假的M/M/C/WV排队   总被引：1，自引：0，他引：1  

陈杰  朱翼隽 《成都信息工程学院学报》2008,23(5):557-561

考虑同步N-策略多重休假和工作休假M/M/c排队,简记为M/M/c（N-WV）。在休假期间,服务员并未完全停止工作而是以较低的速率为顾客服务。用拟生灭过程与矩阵几何解方法,给出了系统稳态队长和稳态条件等待时间的分布。此外,也得到了队长和等待时间的条件随机分解结构及附加队长和附加延迟的分布。  相似文献   

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玄松柏  邢乐林  何志堂  张世伟  李辉 《大地测量与地球动力学》2008,28(4):72-74

???FG5???????????????????????2008??1?????й??????????о?????3053????????????????????????о?????????????????FG5-214??FG5-232???н???????????????????????????????????????н????????????????????????????????????2~3????10 ^-8 ms ^-2??  相似文献   

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高永刚  郭金运  黄金维  岳建平 《大地测量与地球动力学》2008,28(1):45-49

??TOPEX/Poseidon????????????Χ???????ν??з??????ó?????:?????????????Χ???????????ε?????;????????????????????ζ??????????,?????????????????????????????????????????????  相似文献   

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邢乐林  李辉  何志堂  Dong Zhengyao  董正瑶  谈洪波 《大地测量与地球动力学》2008,28(6):38-42

2007??4???2008??6?￡???FG5/232??FG5/214????????????????????????????????????????5?ξ???????????????ι????????????С???2??10 ^-8 ms ^-2??????t??????????????????????С???????????????????????????????????????2007??12????????????2007??4??????5??10 ^-8 ms ^-2?????????????????????仯?????????????????????????????δ?????  相似文献   

基于NDVI城镇土地利用变化检测探讨   总被引：2，自引：0，他引：2  

万雪 《地理空间信息》2009,7(4):111-113

通过归一化植被指数（NDVI）结合影像差值,对经过辐射校正后的1993年和2005年武汉地区TM影像进行了土地利用变化检测,与监督法分类进行比较,得出NDVI更宜于实现变化信息探测和提取。  相似文献