未来不同气候变化情景下我国玉米产量的初步预测   总被引：21，自引：0，他引：21  

熊伟  杨婕  林而达  许吟隆 《地球科学进展》2008,23(10):1092-1101

玉米是我国重要的粮食和饲料作物,研究气候变化对我国玉米产量的影响有重要意义。采用区域气候模式与CERES Maize模型相结合的方法,模拟了基准气候（BS,1961—1990年）和A2、B2两种温室气体排放方案下2011—2100年我国雨养和灌溉玉米产量,初步预测了未来不同气候情景下玉米产量的变化状况。结果表明,如果保持现有的玉米生产状况,气候变化将导致我国玉米主产区的玉米单产普遍降低,总产下降,给玉米生产带来一定经济损失。A2气候变化情景对我国玉米产量的负面影响要大于B2情景。CO2肥效作用可以在一定程度上缓解这种负面影响,其缓解作用对雨养玉米更明显。未来全国玉米主产区的雨养和灌溉玉米的稳产风险及低产出现的概率将会增大,总产的年际波动更剧烈。由于目前研究结果是未考虑农业生产的适应措施而得出的,可能会高估气候变化的负面影响。  相似文献   

从地球系统科学角度浅析中国地貌若干问题研究的新进展   总被引：10，自引：3，他引：7       下载免费PDF全文

杨小平  师长兴  李炳元  朱秉启 《第四纪研究》2008,28(4):521-534

以地球系统中各圈层的相互作用为主线,分析总结了我国沙漠地貌过程、流水地貌过程、冰川地貌过程及风沙地貌过程等领域研究的部分进展。由于我国沙漠地理位置的特殊性,其形成和演变与岩石圈构造变动即青藏高原隆升有着紧密的联系,所以,对我国沙漠形成、演变的研究能为探讨青藏高原隆升历史提供重要佐证。近30年来,有关我国沙漠形成时代的认识更新较快。新的沉积记录显示,我国西北地区的沙漠在中新世时就已经出现了,但沙漠沙丘大规模扩展可能是在中更新世才开始的。既使在晚更新世以来,我国沙漠地区的气候也有过明显波动、沙漠地貌的特征也发生过显著变化。沙漠通过为沙尘暴提供物源,对全球变化产生驱动作用。从地表过程来看,风沙地貌的形成演变不仅受风力作用,而且受流水、湖泊等多种地貌动力过程的影响,地貌类型是各种动力过程共同作用的缩影。古冰川地貌曾是最早发现的第四纪气候变化的证据。随着新的测年技术的出现,学术界对我国第四纪古冰川地貌演化过程有了较系统、全面的认识。流水地貌过程应该是地球上作用区域最广的一种地貌动力过程,对流水地貌过程的认识目前正在向微观和宏观深入。  相似文献   

关中地区的新石器古文化发展与古环境变化的关系   总被引：11，自引：2，他引：9       下载免费PDF全文

吕厚远  张健平 《第四纪研究》2008,28(6):1050-1060

气候环境变化作为影响或制约古文化发展、演化的重要因素,虽然经常受到质疑,但依然被越来越多的考古工作者,包括一些古气候学者所接受。关中地区是我国古代文明重要的发源地之一,为探讨气候环境变化与古文化演化之间可能存在的联系提供了条件。本文对已有很好研究基础的渭南全新世黄土剖面的孢粉、植硅体、蜗牛化石及磁化率和粒度记录进行综合分析,研究得出该区全新世以来有3次突出的气候温暖湿润期（9000～7300aB.P.,6800～5500aB.P.和4500～4300aB.P.）和3次明显而短暂的寒冷干旱期（7300～6800aB.P.,5500～5000aB.P.和约4000aB.P.）。温暖湿润气候期与关中地区的老官台（8000～7000aB.P.）、仰韶（7000～5000aB.P.）、龙山（5000～4000aB.P.）等文化繁盛期几乎是同步的,而发生在7300～6800aB.P.,5500～5000aB.P.及4000aB.P.前后的寒冷干旱气候环境,不是简单的气候冷暖变化,而是影响了生物、水、大气等表生地球系统的气候变化事件,改变了该区的植被类型和生物群落的变迁,这3次气候变化事件时间上大致对应了老官台-仰韶-龙山-夏商文化交替的时间。然而,根据目前的气候记录及时间分辨率还难以判断更次一级的气候环境变化与各文化期不同文化类型变化之间的关系。对关中地区泉护遗址植硅体的分析显示,4500aB.P.以来水稻含量的增加与气候变干的趋势并不一致,推测可能与古人利用渭河水资源种植水稻有关。研究认为关中地区气候环境变化与文化发展之间的关系,有一定的规律可寻,但是由于目前对古气候-古环境变化的幅度、详细的考古文化性质的认识不足,以及时间分辨率和年代学的限制,还无法确切说明什么程度的气候环境变化对哪些文化类型通过什么机制产生了何种程度的影响。  相似文献   

三峡水库建设前后10年库区景观空间格局动态变化研究——以重庆开县为例   总被引：2，自引：1，他引：1  

邵怀勇  仙巍  杨武年  周万村 《测绘科学》2008,33(6):176-178

在遥感和地理信息系统技术的支持下,以1992年和2002年TM图像为基础,采用斑块密度、斑块平均面积、景观形状指数、景观分离度指数、景观多样性指数、景观优势度指数、景观相对聚集度指数深入而全面地研究了三峡工程建设前后十年重庆开县景观空间格局的动态变化,本研究的开展旨在为库区生态环境保护提供科学依据。研究结果表明,十年间研究区景观空间格局发生了明显变化,草地、未利用地、旱地、果园和水田面积净减,森林、建设用地、灌木林和水域面积增加,退耕还林已初见成效。  相似文献   

Time-dependent stress change during failure of rocks     

V.T. Belikov  A.F. Shestakov 《Russian Geology and Geophysics》2008,49(5):350-356

The energy balance of a solid subject to fracture has been explored using heat and mass transfer equations with regard to the volumetric and superficial components. In the suggested model, brittle fracture of a cracked solid considered as a heterogeneous two-phase medium is described by an equation analogous to the Griffith’s criterion for propagation of a single crack. The derived equation is used, together with estimates of relative change in specific interface area, to study the respective change of free strain energy and pressure in rocks associated with failure.  相似文献   

A spectrophotometric measurement of soil cation exchange capacity based on cobaltihexamine chloride absorbance     

Delphine Aran  Armand Maul  Jean-Franois Masfaraud 《Comptes Rendus Geoscience》2008,340(12):865-871

Among numerous methods for cation exchange capacity (CEC) determination for soils and sediments, the cobaltihexamine chloride method is frequently used due to its ability to measure CEC at soil pH. After exchange with Co(NH₃)₆³⁺ ions, CEC is estimated via the measurement of the Co remaining in solution. The modified method proposed allows a more rapid determination of CEC based on the measurement of the absorbance at 472 nm of the cobaltihexamine chloride solution before and after exchange. This method has been applied to various soil's horizons from four sites, selected to cover a wide range of CEC and pH values. The model obtained allows one to calculate CEC from absorbance at 472 nm with 95% confidence intervals. As CEC is of relevant meaning in agronomical and environmental purposes, and more recently in ecotoxicological studies, this modified method can be proposed as a rapid test for CEC evaluation.  相似文献   

大连滨海湿地景观格局变化及其驱动机制   总被引：6，自引：0，他引：6  

姜玲玲  熊德琪  张新宇  张弘 《吉林大学学报(地球科学版)》2008,38(4)

以2000年和2006年TM卫星影像为主要数据源,配合其它非遥感数据,在遥感与地理信息系统技术支持下,运用景观生态学原理,选取反映景观空间结构和景观异质性的指数,对大连地区湿地的整体景观格局和类型景观格局及其动态变化进行定量分析.结果表明:6年间,大连湿地面积减少了97.62 km2;整体景观多样性指数和均匀度指数降低,优势度指数增加;各类景观格局时间序列上也存在明显差异性变化.湿地景观格局指数的变化, 反映了移山填海工业园区的扩大及养殖业的大力发展等人为活动对景观格局的深刻影响.人为活动已成为大连市湿地景观格局变化的主要驱动因子.  相似文献   

An essay on the interactions between climate and society     

Michael H  GLANTZ  Qian YE 《Frontiers of Earth Science》2008,2(3):356-363

There has been increasing concern about the lack of involvement by social scientists and humanists in a global change program, although many social scientists are already directly involved in various aspects of research on environmental change, and their research interests are clearly central to a global change research agenda. Based on a historical review, the role of social science disciplines as well as social science institutes in an emerging multidecadal global change program is discussed. Both “plan of action” and “plan of inaction” are suggested to avoid potential pitfalls due to the rush development of a social science program into the existing global climate change problem.  相似文献   

Climate changing characteristics of Zhangye City in Heihe River basin during 1968–2005     

Mingji Li  Yuxia Ma  Peiji Shi 《Frontiers of Earth Science》2008,2(2):243-248

At present, researches on climate change of the Heihe River basin mainly focus on the relationship between basin climate change and regional water resources, regional desertification and dynamic climatic seasons of sandstorm, but less on climate change of oasis region, where there are more intense and frequent human activities. Based on data of precipitation, temperature, strong wind and dust events frequencies obtained from the six meteorological stations of Zhangye region in Heihe River basin, the features of climate change during 1968–2005 were carefully studied. Results show that the regional temperature rise rate exceeded the average level of China. The annual precipitation changed a little, but the precipitation had a slowly increasing trend in spring and winter. Frequencies of strong wind and sandstorm days show obviously descending trends, which had a close correlation with the regional temperature rise and the precipitation increase in spring and winter. Meanwhile, further human economic activities and exploitations to the oasis in the inland valley of arid regions also affected the climate change of this region, which has a sensitive and fragile eco-environment. __________ Translated from Journal of Desert Research, 2007, 27(6): 1048–1054 [译自: 中国沙漠]  相似文献   

Holocene climate reconstructions of Ulungur Lake (Xinjiang,China) inferred from ostracod species assemblages and stable isotopes     

Qingfeng JIANG  Ji SHEN  Xingqi LIU  Enlou ZHANG 《Frontiers of Earth Science》2008,2(1):31-40

In this paper, the data on the paleoclimatic and paleoenvironmental changes during the Holocene are presented and a discussion is made on a 225-cm-long sediment core from Ulungur Lake, located in Northwest China. The chronology is constructed from six AMS radiocarbon dates on the bulk organic matter. On the basis of the analysis of ostracod assemblages and the shell stable isotopes, the core is divided into three paleoclimatic and paleoenvironmental evolution stages: 9 985–5 250 cal.aB.P. stage is the wettest phase of the core section. The climate changed from moderate-dry to cool-wet, and then to warm-wet in turn, and the lake level rose accordingly, showing the characteristic of a high lake level. 5 250–1 255 cal.aB.P. stage was the driest phase of the core sediment. The climate turned from the early warm-dry to the late warm-wet and the lake level fell and rose again. Finally, the 1 255 cal.aB.P. stage was the medium stage of the section. The temperature was low and then increased after the 1920s and the climate was dry. The whole climatic and environmental evolution records of Lake Ulungur were not only in agreement with the sporopollen record of the same core but also in agreement with the record of environmental changes of adjacent areas. It responded to regional environmental changes and global abrupt climate events, following the westerly climate change mode on 100-year-scale, primarily with cold-wet and warmdry characteristics. __________ Translated from Quaternary Sciences, 2007, 27(3):382–391 [译自:第四纪研究]  相似文献