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过去十年中,在认识上的主要进展之一是关于碳、氮、硫、磷及其它元素生物地球化学循环之中的联系,从而说明了将生态圈分属大气圈、水圈、岩石圈等横断面的传统分法之不合理性。  相似文献   

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中国农业(种植业)的历史发展和地理分布   总被引:6,自引:0,他引:6  
赵松乔 《地理研究》1991,10(1):1-11
本文从种植起源与早期发展、化统农业的发展及现代农业区域开发等几方面论述了我国农业文化发展历史及其地域分布。  相似文献   

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一、区域的选择要执行 START,就需要确定一系列普遍同意的基本上覆盖全球的研究区域,这些研究区该符合所在区域的需要,以及满足全球变化研究计划(IGBP)、世界气候研究计划(WCRP)及其他计划的核心计划的研究需要。为此,参加贝拉焦(Bellagio)会议的代表制定了确定和选择代表性地区的一些原则,并依据这些原则研究了已经提出的一些地区,同时从中选出了几个在实施 START 时应优先考虑的区域。(一)区域选择的原则根据现实考虑,区域性研究网络(RRN)的建立应遵从一个优先顺序,特别是在早期阶段,要着重考虑少数发达国家在主要的全球变化计划中的研究活动。  相似文献   

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苏美全球变化研究计划专著的作者们,在概括阐述了国际地圈一生物圈计划的背景后得出结论:要充分了解全球变化,就必须对现今的景观进行比较精确的模拟,分析特定区域内人为变化的因果,评价社会可能对这些变化的新认识作出反应的条件,以及具有基于具体研究场所的大大加强的地理信息系统。苏联和美国的地理学家参加了全球变化研究的地理学途径,由国际科学联盟理事会倡议,在其国际地圈一生物圈计划中曾列入了关于研究世界环境重大变化的新项目。作为该项目的一部分,苏美地理学家审查了有关的地理学经验。  相似文献   

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滨海旅游是最传统的、主要的旅游形式,也是现代旅游增长最快的领域,在国内外均具有举足轻重的地位。全球变化很可能是由人类活动引起,并且影响着旅游业的发展。旅游业通过使用交通运输系统尤其是航空旅行、旅游目的地住宿餐饮等活动排放大量温室气体,对全球变化做出贡献。可持续滨海旅游以可持续的资源开发和管理为基础,在全球变化视角下,要达到这一目标,需要在滨海旅游模式与产品类型转变、旅游资源利用方式转变、利益相关者协作等方面对滨海旅游资源进行优化开发和有效管理:以绿色思维指导低碳旅游模式,发展生态旅游和替代性旅游等新型产品;提倡降碳减排、发展碳补偿和碳经济、制定碳排放标准、鼓励新型节油节能科技应用;鼓励社区参与,平衡利益相关者的收益和兴趣,尤其是探察当地社区居民、旅游者和政府工作人员对全球变化的看法、态度、责任感和共识。这些措施将在规划—管理—监督—评估动态模型中得到优化。由于相关研究的可用数据有限,本文所引用数据部分来自于对旅游整体的研究结果,是为不足之处。  相似文献   

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采用1982-2015年的GLASS-LAI (Global Land Surface Satellite-Leaf Area Index)遥感数据和CRU(Climatic Research Unit)气象数据,利用Mann-Kendall趋势法分析了过去34 a全球9种植被的叶面积指数(Leaf Area Index,LAI)时空变化特征;使用相关分析和逐步线性回归分别探讨了全球9种植被LAI与降水、温度的年际与月关系。结果表明:①全球植被总体呈现绿化趋势,其中变化较大的是草原、稀树草原、常绿阔叶林和多树草原;在植被生长的绿化和褐化趋势中,面积占比最大的植被类型均为草原,说明草原生态系统易受环境因素的影响。②从年际关系看,草原和开放灌丛的LAI与年均降水多呈正相关关系,而温度对不同纬度植被的LAI存在正负2种影响。其原因为温度升高对中低纬度的植被生长有抑制作用,而对高纬度地区植被生长有促进作用。③从年内关系看,南半球降水和温度共同作用于植被的生长;而北半球除常绿阔叶林的生长与温度关系更为紧密外,其它类型植被的生长主要受降水影响。④逐步线性回归结果表明,当月温度的升高对常绿阔叶林、混...  相似文献   

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Land surface emissivity is one of the important parameters in temperature inversion from thermal infrared remote sensing. Using MOD11C3 of Terra-MODIS L3 level products, spatio-temporal data sets of land surface emissivity in China for 10 years from 2001 to 2010 are obtained. The results show that the land surface emissivity in the northwest desert region is the lowest in China, with little seasonal variations. In contrast, there are significant seasonal variations in land surface emissivity in northeast China and northern Xinjiang, the Qing-hai-Tibet Plateau, the Yangtze River Valley and the eastern and southern China. In winter, the land surface emissivity in the northeast China and northern Xinjiang is relatively high. The land surface emissivity of the Qinghai-Tibet Plateau region is maintained at low value from November to March, while it becomes higher in other months. The land surface emissivity of the Yangtze River Valley, eastern and southern China, and Sichuan Basin varies from July to October, and peaks in August. Land surface emissivity values could be divided into five levels: low emissivity (0.6163-0.9638), moderate-low emissivity (0.9639-0.9709), moderate emis-sivity (0.9710-0.9724), moderate-high emissivity (0.9725-0.9738), and high emissivity (0.9739-0.9999). The percentages of areas with low emissivity, moderate-low emissivity and moderate emissivity are, respectively, about 20%, 10% and 20%. The moderate-high emis-sivity region makes up 40%-50% of China’s land surface area. The inter-annual variation of moderate-high emissivity region is also very clear, with two peaks (in spring and autumn) and two troughs (in summer and winter). The inter-annual variation of the high emissivity region is very significant, with a peak in winter (10%), while only 1% or 2% in other seasons. There is a clear association between the spatio-temporal distribution of China’s land surface emissivity and temperature: the higher the emissivity, the lower the temperature, and vice versa. Emis-sivity is an inherent property of any object, but the precise value of its emissivity depends very much on its surrounding environmental factors.  相似文献   

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长江口悬沙浓度变化的同步性和差异性(英文)   总被引:1,自引:0,他引:1  
The sediment discharge from the Yangtze River Basin has a stepwise decreasing trend in recent years. The impounding of the Three Gorges Reservoir exacerbated this decreasing trend and affected the change of the suspended sediment concentration(SSC) in the Yangtze River Estuary through the transmission effect. The SSC data of the Yangtze River Estuary during 1959–2012 showed that:(1) The SSC in the South Branch of the Yangtze River in the estuary and in the off-shore sea area displayed decreasing trends and decreased less towards the sea. At the same time, the difference in decreasing magnitude between SSC and sediment discharge became bigger towards the sea.(2) For the North Branch the preferential flow did not change much but the SSC tended to decrease, which was mainly caused by the decrease of SSC in the South Branch and China East Sea.(3) Due to the decreased runoff and the relatively strengthened tide, the peak area of the SSC in the bar shoal section in 2003–2012 moved inward for about 1/6 longitude unit compared with that in 1984–2002, and the inward-moving distance was in the order of flood season > annual average > dry season.(4) In the inlet of the South Passage, the SSC decreased mainly because the increase caused by resuspension and shore-groove exchange was less than the decrease caused by the sharp SSC decrease in the basin and the sea areas. The reverse was true in the middle section, where the SSC showed an increasing trend.(5) In the inlet of the North Passage, under the combined influence of decreased flow split and sediment split ratios, the decreased SSC in the basin and the sea area and decreased amount of resuspension, the SSC displayed a decreasing trend. In the middle section, because the increased amount caused by sediment going over the dyke was markedly more than the decreased amount caused by external environments, the SSC tended to increase. Holistically, the sharp decrease in sediment discharge caused synchronized SSC decreases in the Yangtze River Estuary. But there were still areas, where the SSC displayed increasing trends, indicating synchronicity and difference in the response of SSC to the sharp decrease in sediment discharge from the basin.  相似文献   

10.
引言在《全球碳循环的人为干扰》研究中,得出了一组方程,可描述碳的主要同位素和稀有同位素全球周转变化。  相似文献   

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大气中13C 变化的界限我们将认为,方程(24)和(25)中的所有经验数据,除Δδ13Ca 外,都是已知的,且精度较高。我们可把该式右部看做是Δδ13Ca的函数——在从17世纪开始的整个人为扰动时期内大气中13Ca 的相对含量变动量的变化。在方程(24)和(25)的实验数据中既有与时间无关的数值(σ,ζ,Kas*),又有随时间变化的数据(δ13C、Δxa)。从1958年起就开始有系统地测量随时间变化的数据。  相似文献   

13.
Based on the daily runoff data from 20 hydrological stations above the Bengbu Sluice in the Huaihe River Basin during 1956-2010, run test, trend test and Mann-Kendall test are used to analyze the variation trend of annual maximum runoff series. The annual maximum series (AM) and peaks over threshold series (POT) are selected to describe the extreme distributions of generalized extreme value distribution (GEV) and generalized Pareto distribution (GPD). Temporal and spatial variations of extreme runoff in the Huaihe River Basin are analyzed. The results show that during the period 1956-2010 in the Huaihe River Basin, annual maximum runoff at 10 stations have a decreasing trend, while the other 10 stations have an unobvious increasing trend. The maximum runoff events almost occurred in the flood period during the 1960s and 1970s. The extreme runoff events in the Huaihe River Basin mainly occurred in the mainstream of the Huaihe River, Huainan mountainous areas, and Funiu mountainous areas. Through Kolmogorov-Smirnov test, GEV and GPD distributions can be well fitted with AM and POT series respectively. Percentile value method, mean excess plot method and certain numbers of peaks over threshold method are used to select threshold, and it is found that percentile value method is the best of all for extreme runoff in the Huaihe River Basin.  相似文献   

14.
1960-2007年中国地表潜在蒸散发敏感性的时空变化(英文)   总被引:2,自引:0,他引:2  
Potential evapotranspiration (E0), as an estimate of the evaporative demand of the atmosphere, has been widely studied in the fields of irrigation management, crop water demand and predictions in ungauged basins (PUBs). Analysis of the sensitivity of E0 to meteorological factors is a basic research on the impact of climate change on water resources, and also is important to the optimal allocation of agricultural water resources. This paper dealt with sensitivity of E0 over China, which was divided into ten drainage systems, including Songhua River basin, Liaohe River basin, Haihe River basin, Yellow River basin, Yangtze River basin, Pearl River basin, Huaihe River drainage system, Southeast river drainage system, Northwest river drainage system and Southwest river drainage system. In addition, the calculation method of global radiation in Penman-Monteith formula was improved by optimization, and the sensitivities of Penman-Monteith potential evapotranspiration to the daily maximum temperature (STmax), daily minimum temperature (STmin), wind speed (SU2), global radiation (SRs) and vapor pressure (SVP) were calculated and analyzed based on the long-term meteorological data from 653 meteorological stations in China during the period 1960-2007. Results show that: (1) the correlation coefficient between E0 and pan evaporation increased from 0.61 to 0.75. E0 had the decline trends in eight of ten drainage systems in China, which indicates that "pan evaporation paradox" commonly exists in China from 1960 to 2007. (2) Spatially, Tmax was the most sensitive factor in Haihe River basin, Yellow River basin, Huaihe River drainage system, Yangtze River basin, Pearl River basin and Southeast river drainage system, and VP was the most sensitive factor in Songhua River Basin, Liaohe River basin, Northwest river drainage system while Rs was the most sensitive factor in Southwest river drainage system. For the nation-wide average, the most sensitive factor was VP, followed by Tmax, Rs, U2 and Tmin. In addition, the changes in sensitivity coefficients had a certain correlation with elevation. (3) Temporally, the maximum values of STmax and SRs occurred in July, while the maximum values of STmin, SVP and SU2 occurred in January. Moreover, trend analysis indicates that STmax had decline trends, while STmin, SU2, SRs and SVP had increasing trends.  相似文献   

15.
川渝地区气温随地形、经度和纬度的变化(英文)   总被引:3,自引:1,他引:3  
Using the daily temperature data of 95 meteorological stations from Si-chuan-Chongqing Region and its surrounding areas, this paper adopted these methods (e.g., linear regression, trend coefficient, geographical statistics, gray relational analysis and spatial analysis functions of GIS) to analyze the relations of temperature variability with topography, latitude and longitude. Moreover, the rank of gray correlation between temperature variability and elevation, longitude, latitude, topographic position and surface roughness also was measured. These results indicated: (1) The elevation affected temperature variability most obviously, followed by latitude, and longitude. The slope of the linear regression between temperature change rate and elevation, latitude and longitude was 0.4142, 0.0293 and -0.3270, respectively. (2) The rank of gray correlation between temperature change rate and geographic factors was elevation > latitude > surface roughness > topographic position > longitude. The gray correla-tion degree between temperature change rate and elevation was 0.865, followed by latitude with 0.796, and longitude with 0.671. (3) The rate of temperature change enhanced with the increase of elevation. Especially, the warming trend was significant in the plateau and mountain areas of western Sichuan, and mountain and valley areas of southwestern Sichuan (with the warming rate of 0.74℃/10a during the 1990s). However, there was a weak warming trend in Sichuan Basin and its surrounding low mountain and hilly areas. (4) The effects of latitude on temperature change rate presented the specific regulation, which the warming rate of low-latitude areas was more significant than that of high-latitude areas. However, they were consistent with the regulation that the increasing of low temperature controlled most of the warming trend, due to the effects of terrain and elevation on annual mean temperature. (5) Ba-sically, temperature variability along longitude direction resulted from the regular change of elevation along longitude. It was suggested that, in Sichuan-Chongqing Region, special features of temperature variability largely depended on the terrain complexity (e.g., undulations, mutations and roughness). The elevation level controlled only high or low annual mean temperature and the range of temperature change rate in the macro sense.  相似文献   

16.
研究了两种优良固沙植物油蒿(Artemisia ordosica)和柠条(Caragana korshinskii)的光合生理、水分生理和根、茎、叶渗透调节物质的昼夜变化特征。结果显示:空气相对湿度在夜间大幅度回升,植物的昼夜叶温差高于气温差。植物日间呈光合作用,夜间呈呼吸作用,油蒿的光合速率和呼吸速率均高于柠条;日间光合作用出现的光抑制可在日落时迅速恢复。日间气孔导度和蒸腾速率呈现大幅度的波动,在夜间趋于低缓,油蒿日间的调节幅度高于柠条,且在夜间仍维持一定的气孔开度。油蒿根含水量和小枝水势始终高于柠条,但柠条在夜间的根系吸水能力高于油蒿。油蒿根、茎、叶的可溶性糖含量均高于柠条,在夜间叶片的可溶性糖可大量的传输至根部;柠条根、茎、叶的脯氨酸含量均高于油蒿,油蒿的根和叶片在夜间出现较高的脯氨酸累积。植物生理活动的夜间调整对增强午间抗逆性有一定的作用。  相似文献   

17.
东莞地区土地利用变化预测的CBR和CA方法对比研究(英文)   总被引:3,自引:0,他引:3  
Many studies on land use change(LUC),using different approaches and models,have yielded good results.Applications of these methods have revealed both advantages and limitations.However,LUC is a complex problem due to influences of many factors,and variations in policy and natural conditions.Hence,the characteristics and regional suitability of different methods require further research,and comparison of typical approaches is re-quired.Since the late 1980s,CA has been used to simulate urban growth,urban sprawl and land use evolution successfully.Nowadays it is very popular in resolving the LUC estimating problem.Case-based reasoning(CBR),as an artificial intelligence technology,has also been employed to study LUC by some researchers since the 2000s.More and more researchers used the CBR method in the study of LUC.The CA approach is a mathematical system con-structed from many typical simple components,which together are capable of simulating complex behavior,while CBR is a problem-oriented analysis method to solve geographic problems,particularly when the driving mechanisms of geographic processes are not yet understood fully.These two methods were completely different in the LUC research.Thus,in this paper,based on the enhanced CBR model,which is proposed in our previous research(Du et al.2009),a comparison between the CBR and CA approaches to assessing LUC is presented.LUC in Dongguan coastal region,China is investigated.Applications of the im-proved CBR and the cellular automata(CA) to the study area,produce results demonstrating a similarity estimation accuracy of 89% from the improved CBR,and 70.7% accuracy from the CA.From the results,we can see that the accuracies of the CA and CBR approaches are both >70%.Although CA method has the distinct advantage in predicting the urban type,CBR method has the obvious tendency in predicting non-urban type.Considering the entire ana-lytical process,the preprocessing workload in CBR is less than that of the CA approach.As such,it could be concluded that the CBR approach is more flexible and practically useful than the CA approach for estimating land use change.  相似文献   

18.
The international conference on the urban environment was held on May 25-28, 2004 in Shanghai, China. It was co-sponsored by Montclair State University, USA and East China Normal University. A total of some 80 scholars and educators from China and across the world participated in this event. About 150 papers were presented and discussed during this conference. Professor Wang Jianpan, President of East China Normal University delivered the welcoming address. Dr. Susan Cole, Preside…  相似文献   

19.
The runoff of some rivers in the world especially in the arid and semi-arid areas has decreased remarkably with global or regional climate change and enhanced human activities.The runoff decrease in the arid and semi-arid areas of northern China has brought severe problems in livelihoods and ecology.To reveal the variation characteristics,trends of runoff and their influencing factors have been important scientific issues for drainage basin management.The objective of this study was to analyze the variation trends of the runoff and quantitatively assess the contributions of precipitation and human activities to the runoff change in the Huangfuchuan River Basin based on the measured data in 1960-2008.Two inflection points(turning years) of 1979 and 1998 for the accumulative runoff change,and one inflection point of 1979 for the accumulative precipitation change were identified using the methods of accumulative anomaly analysis.The linear relationships between year and accumulative runoff in 1960-1979,1980-1997 and 1998-2008 and between year and accumulative precipitation in 1960-1979 and 1980-2008 were fitted.A new method of slope change ratio of accumulative quantity(SCRAQ) was put forward and used in this study to calculate the contributions of different factors to the runoff change.Taking 1960-1979 as the base period,the contribution rate of the precipitation and human activities to the decreased runoff was 36.43% and 63.57% in 1980-1997,and 16.81% and 83.19% in 1998-2008,respectively.The results will play an important role in the drainage basin management.Moreover,the new method of SCRAQ can be applied in the quantitative evaluation of runoff change and impacts by different factors in the river basin of arid and semi-arid areas.  相似文献   

20.
Plant growth at northern latitudes is highly responsive to the climatic changes that have occurred over recent decades. However, the sensitivity of the phasing of the seasonal cycle of terrestrial ecosystems to a changing environment remains less widely understood. We present an investigation and comparative study of large-scale changes in seasonal cy-cling of both land surface temperature and plant growth. Our results have shown trends in-dicating a marked increased towards overall plant productivity by ~3% from 1982 to 2005, reduced trends in seasonal variation at low-mid latitudes by ~2%, increased trends in sea-sonal variations at mid-high latitudes by ~7%, and an earlier phase in northern terrestrial ecosystems (~1.1 days) in parallel with changes in the phasing of surface temperatures at northern latitudes over the 24 years in this study. These shifts in annual cycles of terrestrial vegetation appear to have a distinct geographical zonality and are dependent upon latitudinal changes in climatic variables. More conspicuous changes in overall vegetation productivity and the seasonal phase of ecosystems have been observed in Eurasia compared to North America, largely because of a more rapid rise in temperature. Our results state that changing climate boosts plant growth at northern latitudes, but also alters the phase and seasonal variations of the annual cycle of terrestrial ecosystems.  相似文献   

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