哈萨克斯坦粮食价格形成机制分析   总被引：1，自引：0，他引：1  

李宁 《世界地理研究》2010,19(4):40-46,39

自2006年下半年以来,哈萨克斯坦同全球其他国家一样出现了粮食价格的持续上涨的现象,由食物价格上涨引发了消费物价指数的暴涨,引起了哈萨克斯坦国内的社会抢购粮食风潮和社会动荡。而哈萨克斯坦是世界第六大谷物出口国,第一大面粉出口国为什么会受到全球粮食危机的冲击,导致国内粮食价格快速且大幅度的上涨。本文通过对哈萨克斯坦粮食价格的波动指数的研究,表明了哈萨克斯坦粮食价格动具有特殊的规律性的显著特征,提出了哈萨克斯坦的粮食价格波动主要是受供求关系、自然灾害、国际市场传导、农业政策变化等因素影响。  相似文献   

中国东北地区林地面积变化的动态模拟   总被引：1，自引：0，他引：1  

邓祥征  姜群鸥  战金艳  何书金  林英志 《地理学报(英文版)》2010,20(4):495-509

There is plenty of forests in Northeast China which contributes a lot to the conservation of water and land resources, produces timber products, and provides habitats for a huge number of wild animals and plants. With changes of socio-economic factors as well as the geophysical conditions, there are dramatic changes on the spatial patterns of forest area. In this sense, it is of great significance to shed light on the dynamics of forest area changes to find the underlining reasons for shaping the changing patterns of forest area in Northeast China. To explore the dynamics of forest area change in Northeast China, an econometric model is developed which is composed of three equations identifying forestry production, conversion from open forest to closed forest and conversion from other land uses to closed forest so as to explore the impacts on the forest area changes from demographic, social, economic, location and geophysical factors. On this basis, we employ the Dynamics of Land System (DLS) model to simulate land-use conversions between forest area and non-forest cover and the land-use conversions within the sub-classes of forest area for the period 2000–2020 under business as usual scenario, environmental protection scenario and economic growth scenario. The simulation results show that forest area will expand continuously and there exist various kinds of changing patterns for the sub-classes of forest area, for example, closed forest will expand continuously and open forest and shrub will decrease a little bit, while area of other forest will keep intact. The research results provide meaningful decision-making information for conserving and exploiting the forest resources and making out the planning for forestry production in the Northeast China region.  相似文献   

Twenty years of change in the Fijian periphery: The case of the Kadavu Island     

Michael Sofer 《Singapore journal of tropical geography》2009,30(3):343-357

This paper reviews changes in the development and peripheralized status of the Fijian island of Kadavu from a 20‐year perspective. A combination of microgeographic studies in three villages and a mesogeographical analysis show that the conditions of internal dependency found in Kadavu in the early 1980s had not changed much: the pattern of cash crop production and trade remained almost entirely dependent on the yaqona (Pacific kava) beverage crop; shipping services provided by core agents had not improved; the island had experienced significant outmigration; and government initiatives to change the trend were limited. These elements perpetuate a core–periphery structure in Fiji that hampers the development of a self‐sufficient periphery. For Kadavu villagers, however, the benefits derived from the continued form of non‐capitalist production afford them a certain degree of autonomy vis‐à‐vis the market economy, which might be to their advantage under the ongoing conditions of peripheralization.  相似文献   

Interactions between freshwater input, light, and phytoplankton dynamics on the Louisiana continental shelf     

John C. Lehrter  Michael C. Murrell  Janis C. Kurtz   《Continental Shelf Research》2009,29(15):1861-1872

We examined the effects of freshwater flow and light availability on phytoplankton biomass and production along the Louisiana continental shelf in the region characterized by persistent spring–summer stratification and widespread summer hypoxia. Data were collected on 7 cruises from 2005 to 2007, and spatially-averaged estimates of phytoplankton and light variables were calculated for the study area using Voronoi polygon normalization. Shelf-wide phytoplankton production ranged from 0.47 to 1.75 mg C m⁻² d⁻¹ across the 7 cruises. Shelf-wide average light attenuation (k_d) ranged from 0.19–1.01 m⁻¹ and strongly covaried with freshwater discharge from the Mississippi and Atchafalaya Rivers (R²=0.67). Interestingly, we observed that the euphotic zone (as defined by the 1% light depth) extended well below the pycnocline and to the bottom across much of the shelf. Shelf-wide average chlorophyll a (chl a) concentrations ranged from 1.4 to 5.9 mg m⁻³ and, similar to k_d, covaried with river discharge (R²=0.83). Also, chl a concentrations were significantly higher in plume versus non-plume regions of the shelf. When integrated through the water-column, shelf-wide average chl a ranged from 26.3 to 47.6 mg m⁻², but did not covary with river discharge, nor were plume versus non-plume averages statistically different. The high integrated chl a in the non-plume waters resulted from frequent sub-pycnocline chl a maxima. Phytoplankton production rates were highest in the vicinity of the Mississippi River bird's foot delta, but as with integrated chl a were not statistically different in plume versus non-plume waters across the rest of the shelf. Based on the vertical distribution of light and chl a, a substantial fraction of phytoplankton production occurred below the pycnocline, averaging from 25% to 50% among cruises. These results suggest that freshwater and nutrient inputs regulate shelf-wide k_d and, consequently, the vertical distribution of primary production. The substantial below-pycnocline primary production we observed has not been previously quantified for this region, but has important implications about the formation and persistence of hypoxia on the Louisiana continental shelf.  相似文献   

滨州沿海蒸发量与海盐产量的关系研究   总被引：1，自引：0，他引：1       下载免费PDF全文

刘昭武  王凤娇  牛丽玲  王立静 《气象与环境学报》2009,25(1):31-34

海盐生产主要依靠自然蒸发,蒸发量预报对海盐生产有重要的指导作用。通过对1993—2007年滨州沿海蒸发量和海盐产量的分析,海盐产量的时间分布特征与净蒸发量基本一致,净蒸发量是影响海盐生产的决定性因素。分析蒸发量与气象要素之间的关系,分月建立了逐步回归方程,经检验可作为蒸发量的一种客观预报方法。  相似文献   

1988—2007年辽宁主要农业气象灾害分析   总被引：22，自引：6，他引：16       下载免费PDF全文

赵先丽  李丽光  贾庆宇  谢艳兵  周广胜 《气象与环境学报》2009,25(2):33-37

应用灰色关联分析方法,对1988—2007年辽宁主要农业气象灾害(旱灾、洪涝灾害、风雹灾和霜冻灾害)受灾面积与粮食总产量的关联度进行动态分析。结果表明：对于受灾除了干旱灾害呈上升趋势外,其他灾害都呈下降趋势;对于成灾,洪涝灾害和风雹灾害呈下降趋势,其他灾害呈上升趋势。旱灾对辽宁农业粮食生产造成的影响程度最大,其次是洪涝灾害、霜冻灾害和风雹灾害。  相似文献   

岩石圈内部第二深度空间金属矿产资源形成与集聚的深层动力学响应   总被引：9，自引：1，他引：8       下载免费PDF全文

滕吉文  杨立强  刘宏臣  闫雅芬  杨辉  张洪双  张永谦  田有 《地球物理学报》2009,52(7):1734-1756

中国的快速工业化发展和经济腾飞必须有大量金属矿产资源的支撑,在共享世界资源的同时,其根本出路在于立足本土．因此提出第二深度空间（500～2000 m）金属矿产资源的找矿勘探新理念．通过对国内外金属矿产资源地球物理勘探发展的概况分析和研究提出：①金属矿产资源的集聚和分布受控于地壳内部物质与能量的交换和其深层动力过程;②在地壳内部第二深度空间存在着丰富的矿产资源,包括大型和超大型矿床;③必须充分发挥高精度地球物理探测方法的效能,并进行综合技术集成．  相似文献   

东北草原区产草量和载畜平衡的遥感估算   总被引：6，自引：2，他引：4  

徐斌  杨秀春 《地理研究》2009,28(2):402-408

基于国内外相关研究进展,结合国家农业部草原遥感监测相关任务,依托大量的草原地面样方数据源,开展了东北草原区产草量和载畜平衡的遥感估算研究。主要结论有:(1)指数模型是进行草原区产草量遥感估算的优化模型,模型的估产精度达到80%以上;(2)2007年东北草原鲜产草量总计16916万吨,折合干草5094万吨;鲜重单产为4562kg/ha,折合成干重单产为1374kg/ha;(3)2007年东北草原区75%以上的牧区和半牧区县(旗)牲畜超载,牧区载畜平衡指标为32.23%,半牧区载畜平衡指标为48.51%。本文可为东北草原区的畜牧业发展规划提供科学依据。  相似文献   

企业信息技术应用与产业链空间变化——以中国服装纺织企业为例   总被引：2，自引：2，他引：0  

丁疆辉  宋周莺  刘卫东 《地理研究》2009,28(4):883-892

信息通信技术(ICTs)在经济活动空间重组过程中的作用逐渐被认同,然而不同的空间层级不同的部门其重组过程与特征表现各异,形成的观点和争论多样。企业作为最基本的经济单元在信息化浪潮中发生的变化成为一个重要研究议题。本文以服装纺织企业为研究案例,通过企业访谈获取资料,旨在探讨传统制造业在信息技术下的演变特征,尤其是在信息技术下基于时间成本的生产链空间组织的变化特征。本文主要对服装纺织企业具体的信息技术应用进行了剖析,分析了信息技术下不同发展程度企业生产链空间组织特征及其变化。结果发现服装纺织企业在信息技术下,其设计、生产、配送的周期快速缩减,证明了时间因素在信息技术导致生产链空间组织变革中的重要意义;同时发现信息技术对传统加工制造型纺织服装企业的影响主要表现为生产链某个环节管理功能的加强;而对于产业升级后的企业来说,信息技术对整个生产链空间组织的影响明显。  相似文献   

遥感物候学研究进展   总被引：19，自引：2，他引：17  

陈效逑  王林海 《地理科学进展》2009,28(1)

植物物候现象是环境条件季节和年际变化最直观、最敏感的生物指示器,其发生时间可以反映陆地生态系统对气候变化的快速响应.近年来,遥感物候观测因其具有多时相、覆盖范围广、空间连续、时间序列较长等特点,已成为揭示植被动态对全球气候变化响应与反馈的重要手段.文章在介绍植物物候遥感监测的数据集及其预处理方法的基础上.从植物物候生长季节的划分、植物物候与气候变化、植物物候与净初级生产量、植物物候与土地覆盖、植物物候与农作物估产等方面系统阐述了近5年来国内外遥感物候学研究的重要进展,并针对目前研究中存在的问题,提出近期遥感物候研究的主要方向:(1)发展一种更具普适性的物候生长季节划分方法;(2)通过开展植物群落的物候观测和选择合适的尺度转换方法,统一地面与遥感的空间信息;(3)定量分析植物物候变化对人类活动的响应机制;(4)选择适宜的数学方法和模型,实现各种不同分辨率遥感数据的融合;(5)通过动态模拟,预测植物物候对未来气候变化的响应.  相似文献