Studies of Cainozoic environmental change in Tasmania and coastal East Antarctica: a review     

Eric A. Colhoun 《The Australian geographer》1993,24(1):3-11

Observational studies on Cainozoic environmental changes in both Tasmania and East Antarctica have led to important modifications in the accepted interpretation of the history of glaciation for each area. Many contributors have played an important role in the processes of investigation leading to the present state of knowledge. A crucial role has been played by the integration of the methods of glacial geomorphology, stratigraphy, sedimentology and dating methods. From studies based on combinations of these approaches, a model of multiple glaciations has been developed to explain observed features in Tasmania. This model is complemented by studies of vegetation history, largely through pollen analysis. A less complete picture of the history of ice‐sheet fluctuations in East Antarctica is beginning to emerge from similar applications of cross‐disciplinary studies.  相似文献   

Relationships of Louisiana Colonial Land Claims with Potential Natural Vegetation and Historic Standing Structures: A GIS Approach*   总被引：1，自引：0，他引：1  

Peter B. Mires 《The Professional geographer》1993,45(3):342-350

Louisiana's French, Spanish, and British colonial administrations left a vivid imprint on the landscape in the form of unique cadastral survey systems. The collective distribution of these colonial land claims presents a picture of the colonial occupation of the state. Settlement shows up clearly along the waterways of the bayou state. Equally significant are the areas devoid of land claims. This paper discusses the compilation of the colonial Louisiana land claims map and demonstrates its utility to GIS-based historical geography and historic preservation. By merging this map with other digitized datasets such as potential natural vegetation and historic structures, the seemingly chaotic 18th century occupance of an extremely heterogeneous physical environment becomes patterned, and prior assumptions about the colonial settlement process may be tested with greater precision.  相似文献   

CLIMATE CHANGE AND NATURAL VEGETATION IN CHINA          下载免费PDF全文

Wang Futang  Zhao Zongci 《Acta Meteorologica Sinica》1994,8(1):1-8

The climate change scenarios due to the human activity for East Asia and China by 2050 have been estimated bymeans of a simple global social-economic-climate-impact model combined with seven GCMs.The climate change sce-narios present that the annual mean temperature might increase obviously,by about 1.4℃,and the annual total precipi-tation might increase by about 4% in whole China in comparison with the present climate.The change of the precipita-tion might be much smaller than that of the temperature.The potential impacts of human activity-induced climate change on natural vegetation in China were estimated us-ing the vegetation-climate model developed specially for Chinese vegetation types and different climate change scenariosderived from seven GCMs for 2050.All scenarios suggest a great change in natural vegetation although details of pre-dicted types vary among the scenarios.There will be a northward shift of the vegetation types,with increase in the arealextent of tropical rainforests and decrease of the cold temperate coniferous forest and tundra.Consequently,consideringthese changes and shifts,especially in combination with the likely negative balance of precipitation andevapotranspiration,the moisture stress,i.e.,less water availability arises,the possible influences of climate change onChinese agriculture is also assessed roughly in this paper.  相似文献   

沙坡头人工植被区和流动沙丘上热量平衡观测研究   总被引：9，自引：0，他引：9  

刘树华  辛国君  陈荷生  刘元波  冯金朝  刘立超 《气象》1994,20(1):9-12

采用流动沙丘上人工植被和裸露流动沙丘下垫面近地层微气象实测资料，应用波文比法，计算了近地层感热和潜热通量＾２），并与作者在防风林干旱裸田和湿润小麦植被农田的结果进行比较分析。结果表明：在雨季的沙坡头地区流动沙丘人工植被上净辐射通量较强，可达６００Ｗ。ｍ＾－２以上，而净辐射的７０％左右的能量用于地表的蒸散，而感热散失和土壤贮存能量各占１５％左右；裸露流动沙丘上由于地表反射率大而净辐射通量小于植被区，  相似文献   

长江中下游近百年气候冷暖变化对农业生态环境的影响          下载免费PDF全文

张养才  谈建国 《应用气象学报》1994,5(2):203-210

分别统计分析了上海、合肥、金华、武汉、长沙、南昌、吉安、衡阳等站生长季热量（﹥10 ℃积温及持续日数）和越冬期低温（﹤０℃负积温及极端最低气温）变化特征。运用谱分析方法，提出长江中下游地区气候冷暖变化的周期及长期波动趋势。同时，预测本世纪末，长江中下游地区气候冷暖波动对建立高产、优质、高效的现代农业可能是一种潜在威胁；指出在长江中下游地区农业生产过程中必须重视气候投入，突破传统农业经验，优化农业耕作轮作栽培制度，建设对气候变化具有强的调控功能的新的农业生态系统。  相似文献   

Derivation of vegetative variables from a landsat tm image for modelling soil erosion   总被引：1，自引：0，他引：1  

Steven M. De Jong 《地球表面变化过程与地形》1994,19(2):165-178

A study was carried out to assess the potential use of satellite thematic mapper (TM) images to produce maps of vegetation-related variables for erosion modelling. In a Mediterranean study area in southern France the (semi-)natural vegetation was described at 33 field plots using four quantitative methods: the Fosberg structural classification system, the cover and management factor of the Universal Soil Loss Equation, the leaf area index and the total percentage cover. After radiometric correction of the image, the spectral TM bands were processed following three different methods. Each method aimed at combining the data of the six spectral TM bands into a single band in such a way that the resulting image displayed optimal information on green vegetation cover. The algorithms used comprise the normalized difference vegetation index, the conventional ‘tasselled cap’ transformation and a locally tuned tasselled cap transformation. Only slight differences were found between the different methods to calculate spectral vegetation indices for this particular case. Furthermore, the correlations between the field variables and image-derived spectral indices are generally small. The largest correlations were found for the normalized vegetation index and the leaf area index (r + 0·71) and for the normalized vegetation index and Fosberg's structural vegetation classes (r + 0·76). However, Fosberg's method results in very general classes, which are of little use for soil erosion models. Furthermore, the spectral indices appeared to be sensitive for the vitality of the vegetation. Consequently, an area covered by a sensed, senescent vegetation will not yield a large value for the spectral index, but its soil is protected against splash erosion. This might lead to a misinterpretation of the soil protective cover when satellite images are used. A final conclusion is that a balance has to be found between the more accurate, but time-consuming field surveys to gather information on erosion-controlling factors and a certain loss of accuracy associated with the use of quick and easy remote sensing methods.  相似文献   

珠江三角洲全新世环境变化与文化起源及传播的关系   总被引：6，自引：2，他引：6  

翁齐浩 《地理科学》1994,14(1):1-8

  相似文献   

沙漠人工植被和流动沙丘的小气候特征观测研究   总被引：11，自引：0，他引：11  

刘树华  陈荷生 《干旱区地理》1994,17(1):16-23

本文利用１９９２年８月在中国科学院沙坡头治沙试验研究站沙漠人工植被防护体系和流动沙丘下垫面近地面层的微气象观测资料，分析了其小气候特征，效应的物理机制及实际和理论意义。  相似文献   

福建地貌基本特征与农业生产的关系   总被引：7，自引：0，他引：7  

赵昭Bing 《地理学报》1993,48(2):143-151

本文首先从发展农业生产角度出发,分析了福建地貌的基本特征及其对农业生产的直接和间接影响。继而论述了地貌与农业自然灾害的关系,指出了坡度陡、降水强度大和黑云母花岗岩分布三者相结合的部位是农业生态脆弱的地段。最后,根据福建山河分布格局,提出改善福建农业生态的根本性措施——建立防护林体系。  相似文献   

松花江—辽河流域地下水资源及其生态环境问题          下载免费PDF全文

郭晓东  王晓光  刘强  王长琪  肖长来  程旭学 《中国地质》2021,48(4):1062-1074

松花江—辽河流域(简称松辽流域)是中国重要的商品粮基地,地下水资源对维护中国粮食安全具有重要作用。2019年松辽流域地下水资源量为797.31×10~8m~3/a,地下水开发利用量为276.4×10~8m~3。松辽流域地下水面临着水资源局部短缺,局部水位持续下降,"三氮"污染加剧,以及湿地萎缩、土地荒漠化、盐渍化等资源、环境与生态问题。本文对这些问题进行驱动因素分析,主要是气温升高导致水稻适宜区扩大,土地利用方式改变,耕地面积特别是水田面积大幅增加,造成地下水过量开采、地下水面源污染加剧;水库的大量修建加剧干旱缺水地区河道径流减少,地下水补给来源不足,造成地下水供水能力下降,地下水位下降。针对这些问题,提出了加强水资源调查监测,开展水资源合理配置研究,实行地表水和地下水联合调度;加强水资源管理制度建设,强化制度刚性约束;调整农业种植结构,推进节水灌溉,提高水资源利用效率等建议措施。  相似文献