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1.
With basic information from 8353 archaeological sites, this study describes a holistic spatial-temporal distribution pattern of archaeological sites of the prehistoric culture sequence from 9.5 ka BP (ka BP = thousands of years before 0 BP, where "0 BP" is defined as the year AD 1950) to 2.3 ka BP in the region that extends from the Yanshan Mountains to the Liaohe River Plain(i.e., the Yan-Liao region) in northern China. Based on spatial statistics analysis – including the spatial density of the sites and Geographic Information System nearest-neighbour analysis, combined with a review of environmental and climatic data – this paper analyses cultural evolution, the spatial-temporal features of the archaeological sites and human activities against the backdrop of climatic and environmental changes in this region. The results reveal that prehistoric cultural evolution in the Yan-Liao region is extensively influenced by climatic and environmental changes. The Xinglongwa, Zhaobaogou and Fuhe cultures, which primarily developed during a habitable period from 8.5 ka BP to 6.0 ka BP with strong summer monsoons, have similar maximum density values, spatial patterns and subsistence strategies dominated by hunting-gathering. Significant changes occurred in the Hongshan and Lower Xiajiadian cultures, with a significant increase in numbers and densities of sites and a slump in average nearest-neighbour ratio when the environment began to deteriorate starting in 6.0 ka BP. Additionally, with the onset of a weak summer monsoon and the predominance of primitive agriculture, sites of these two cultures present a different type of concentric circle-shaped pattern in space. As the environment continuously deteriorated with increasing aridity and the spread of steppe, more sites were distributed towards the south, and primitive agriculture was replaced by livestock husbandry in the Upper Xiajiadian culture. The most densely populated areas of the studied cultures are centralized within a limited area. The Laohahe River and Jiaolaihe River basins formed the core area in which most archaeological sites were distributed during the strong summer monsoon period and the first few thousand years of the weak summer monsoon period.  相似文献   

2.
Geographically explicit historical land use and land cover datasets are increasingly required in studies of climatic and ecological effects of human activities. In this study, using historical population data as a proxy, the provincial cropland areas of Qinghai province and the Tibet Autonomous Region(TAR) for 1900, 1930, and 1950 were estimated. The cropland areas of Qinghai and the TAR for 1980 and 2000 were obtained from published statistical data with revisions. Using a land suitability for cultivation model, the provincial cropland areas for the 20 th century were converted into crop cover datasets with a resolution of 1 × 1 km. Finally, changes of sediment retention due to crop cover change were assessed using the sediment delivery ratio module of the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST) model(version 3.3.1). There were two main results.(1) For 1950–1980 the fractional cropland area increased from 0.32% to 0.48% and land use clearly intensified in the Tibetan Plateau(TP), especially in the Yellow River–Huangshui River Valley(YHRV) and the midstream of the Yarlung Zangbo River and its two tributaries valley(YRTT). For other periods of the 20 th century, stability was the main trend.(2) For 1950–1980, sediment export increased rapidly in the Minhe autonomous county of the YHRV, and in the Nianchu River and Lhasa River basins of the YRTT, which means that sediment retention clearly decreased in these regions over this period. The results of this assessment provide scientific support for conservation planning, development planning, or restoration activities.  相似文献   

3.
长江上游社会经济因子对侵蚀产沙的影响   总被引:1,自引:0,他引:1  
In recent years,the role of human activities in changing sediment yield has become more apparent for the construction of hydraulic engineering and water conservation projec-tions in the Upper Yangtze River,but it has not been evaluated at the macro scale.Taking Sichuan Province and Chongqing City as an example,this paper studies the relationship between socio-economic factors and sediment yield in the Upper Yangtze River based on section data in 1989 and 2007.The results show that sediment yield is significantly correlated with population density and cultivated area,in which the former appears to be more closely related to sediment yield.Moreover,in the relation of sediment yield vs.population density,a critical value of population density exists,below which the sediment yield increases with the increase of population density and over which the sediment yield increases with the decrease of population density.The phenomenon essentially reflects the influence of natural factors,such as topography,precipitation and soil property,and some human activities on sediment yield.The region with a higher population density than critical value is located in the east of the study area and is characterized by plains,hills and low mountains,whereas the opposite is located in the west and characterized by middle and high mountains.In the eastern region,more people live on the lands with a low slope where regional soil erosion is slight;therefore,sediment yield is negatively related with population density.In contrast,in the western region,the population tends to aggregate in the areas with abundant soil and water resources which usually lead to a higher intensity of natural erosion,and in turn,high-intensity agricultural practices in these areas may further strengthen local soil erosion.It is also found that popu-lation tends to move from the areas with bad environment and high sediment yield to the areas with more comfortable environment and less sediment yield.The natural factors have greater influence on sediment yield of western region than that of eastern region.Generally,the natural factors play a dominant role on sediment yield in the Upper Yangtze River.  相似文献   

4.
Based on the comprehensive analyses of 18 core profiles’sedimentary sequences and lithological characteristics in Jianghan-Dongting Basin of the middle reaches of the Yangtze River and the spatial-temporal distribution of archeological sites in this area,we reconstructed the Holocene hydro-environmental evolution,and its relationship with human occupation.The comparison reveals:11.5–5.5 ka BP,the water level of rivers and lakes in the middle Yangtze River appeared a rising trend,concurrently,under the development of Neolithic culture and rice agricultural activities,human occupation extended from piedmont plain to inner basin plain in the study area.The water level fell in 5.5–4.0 ka BP,meanwhile,the number of human settlements of Qujialing-Shijiahe culture rapidly increased,especially in the inner basin plain.The water level rose again around 4.0 ka BP,floods spread massively in this period,which led to the decline of Shijiahe culture.The main causes for hydro-environmental evolution in the study area are the fluctuation of sea level and the aggradation of fluvio-lacustrine sediments.  相似文献   

5.
In this paper, we analyzed the spatial patterns of cultivated land change between 1982 and 2011 using global vector-based land use/land cover data.(1) Our analysis showed that the total global cultivated land area increased by 528.768×104 km~2 with a rate of 7.920×104 km~2/a, although this increasing trend was not significant. The global cultivated land increased fastest in the 1980 s. Since the 1980 s, the cultivated land area in North America, South America and Oceania increased by 170.854×104 km~2, 107.890×104 km~2, and 186.492×104 km~2, respectively. In contrast, that in Asia, Europe and Africa decreased by 23.769×104 km~2, 4.035×104 km~2 and 86.76×104 km~2, respectively. Furthermore, the cultivated land area in North America, South America and Oceania exhibited significant increasing trends of 7.236× 104 km~2/a, 2.780×104 km~2/a and 3.758×104 km~2/a, respectively. On the other hand, that of Asia, Europe and Africa exhibited decreasing trend rates of –5.641×104 km~2/a, –0.831×104 km~2/a and –0.595×104 km~2/a, respectively. Moreover, the decreasing trend in Asia was significant.(2) Since the 1980 s, the increase in global cultivated lands was mainly due to converted grasslands and woodlands, which accounted for 53.536% and 26.148% of the total increase, respectively. The increase was found in southern and central Africa, eastern and northern Australia, southeastern South America, central US and Alaska, central Canada, western Russia, northern Finland and northern Mongolia. Among them, Botswana in southern Africa experienced an 80%–90% increase, making it the country with the highest increase worldwide.(3) Since the 1980 s, the total area of cultivated lands converted to other types of land was 1071.946×104 km~2. The reduction was mainly converted to grasslands and woodlands, which accounted for 57.482% and 36.000%, respectively. The reduction occurred mainly in southern Sudan in central Africa, southern and central US, southern Russia, and southern European countries including Bulgaria, Romania, Serbia and Hungary. The greatest reduction occurred in southern Africa with a 60% reduction.(4) The cultivated lands in all the continents analyzed exhibited a trend of expansion to high latitudes. Additionally, most countries displayed an expansion of newly increased cultivated lands and the reduction of the original cultivated lands.  相似文献   

6.
Mountains in western China, hosted rich biodiversity and millions of people and inhabitant with vital ecosystem services, had experienced the most serious biodiversity loss with fragile ecological problems. Even though increasing attentions had been paid to this issue, we still lacked efficient methods to assess the change of plant biodiversity at medium/large scale due to the poor data and co-existing multiple habitat types. This study proposed an integrated method combining InVEST-habitat quality model, NPP and landscape pattern indexes to analyze the spatial heterogeneity of plant biodiversity and its spatiotemporal change on raster cell scale. The results indicated that plant biodiversity service was high in Bailongjiang watershed with obvious spatial pattern variations. The land area containing higher plant biodiversity were 3161 km2, which mainly distributed in the National Nature Reserve and forestry area. While the areas with lower plant biodiversity accounted for 37.67% and mainly distributed in the valleys between Zhouqu-Wudu-Wenxian County, the valley of Minjiang in Tanchang County and alpine mountain snow-covered regions. During 1990–2010, plant biodiversity level tended to increase and the higher plant biodiversity area increased from 14.13% to 17.15% due to ecological restoration and afforestation, while plant biodiversity decreased in the area with intensive human activities, such as cultivated land, urban and rural land. The results showed that combining InVEST-habitat quality model, NPP and landscape pattern indexes can effective reveal mountain plant biodiversity change. The study was useful for plant biodiversity conservation policy-making and human activity management for the disaster-impacted mountainous areas in China.  相似文献   

7.
The temporal-spatial geographic distribution of archaeological sites and its feature between 10.0–2.8 ka BP(ka BP= thousands of years before 0 BP, where "0 BP" is defined as the year AD 1950) were determined, based on GIS spatial analysis in the Poyang Lake Basin. The relationship between geographic distribution of sites of different periods under subsistence existence of ancient civilizations, climate and environmental change was investigated. The results revealed numerous archaeological sites of the Neolithic Age(10.0–3.6 ka BP). The sites were mainly located in the northern part of the Poyang Lake Basin, a hilly and mountainous area with many river terraces suitable for the development of human civilization. The number of archaeological sites rapidly increased during the Shang and Zhou dynasties(3.6–2.8 ka BP) and spread widely on the floodplains of the middle and lower reaches of Ganjiang River and onto the west, south, and southeast beach areas of the Poyang Lake. Holocene records of climate change suggested that it was possible that climate fluctuations had a great impact on human evolution in the study area. Before 3.6 ka BP, westward and northward expansion of Neolithic cultures in the Poyang Lake watershed occurred under the background of climate amelioration(becoming warmer and wetter). The ancient people lived in the hilly areas with high elevation. The simple mode of a fishing and gathering economy was mostly suited to this area in the early Neolithic Age. The scope of human activities was expanded and cultural diversity developed in the late Neolithic Age. However, with population growth and increasing survival pressure in a dry-cold climatic stage after 3.6 ka BP, this simple living mode had to be abandoned, and various forms of economy, the majority being agriculture, were developed on flood plains of the lower reaches of numerous rivers around Poyang Lake. This promoted flourishing of the Bronze culture of South China.  相似文献   

8.
Sandy desertification in the Shule River Basin has expanded dramatically during the past 30 years. We evaluated the status, evolution, and main causes of sandy desertification by interpreting Landsat images which were acquired in 1978, 1990, 2000, 2005, and 2010, and analyzing the relevant meteorological data. The results show there was 3,477.95 km2, 3,733.32 km2, 3,620.29 km2, 3,565.65 km2, and 3,557.88 km2 of sandy desertified land in 1978, 1990, 2000, 2005, and 2010, respectively. From 1978 to 1990, not only the area of sandy desertified land (SDL) but also the degree of SDL levels increased. From 1990 to 2010 there was widespread restoration of SDL but the recovery trend of SDL gradually slowed. Although climate change contributes to expanding sandy desertification, human activities can either accelerate or reverse trends of natural sandy desertification. Some detrimental human activities can accelerate sandy desertification, but, conversely, desertification control measures such as the Three-North Shelter Forest Project and watershed rehabilitation programs in areas including the Shule River Basin resulted in many SDL being turned into grasslands or forest lands when shrubs and trees were planted to fix mobile sands at the edges of oases and cities. With population growth, much SDL has been reclaimed as farm land using water-saving agricultural methods or has been turned into built-up land as a result of urbanization.  相似文献   

9.
A total of 1362 archaeological sites from the Paleolithic Age to the Warring States time in Hubei Province increase gradually from west to east and from high land to low land.The number of Paleolithic sites with altitude of 50-500 m account for 78% of the whole,while 71%-95% of sites from the Neolithic Age to the Warring States time mainly distribute at the areas of 0-200 m.The temporal-spatial distribution of archeological sites in this area is affected by two factors.For one thing,the human beings of every period need to choose the first or the second terrace as living sites which are near water source and are easy to withstand flood.Additionally,affecting by the regional tectonic uplift since the Holocene,down cutting of rivers can form new river valley,and lateral erosion and accumulation of river in stable time of tectonic movement can result in increasing of many new terraces.So,the human beings migrated to adapt to the change of terrace location,leading to the sites increase gradually in the lower areas of the central and eastern parts of this province.For other things,the temporal-spatial distribution of archeological sites in this area is affected by the climate condition.The Paleolithic sites mostly distribute in the Hanshui River Valley in northeastern Shiyan,southeast of Jinzhou and east of Jinmen,which is because rivers distributed in higher areas in this period.During the Chengbeixi Culture period,the sites are rare in the quondam Paleolithic sites distribution area,but increase obviously along the Yangtze River near the southwest Yichang.The spore-pollen record of Dajiuhu Basin indicates that only 23 Chengbeixi cultural sites may be related to more precipitation and flood during the Holocene wet and hot period.The Daxi Culture,Qujialing Culture and Shijiahe Culture are corresponding to middle and top of the Dajiuhu spore-pollen Zone Ⅳ,during which the climate is in order as a whole and is propitious to agricultural development.In the Qujialing Culture period,32 of original 34 Daxi cultural sites disappeared,while 90 sites increase abruptly in the higher highlands in the north of Xiangfan-Jinmen-Xiaogan,which may respect with enlarging of water areas.The Chu Culture period is corresponding to Dajiuhu spore-pollen Zone V,which is in warm and dry Holocene phase,but it seems that the climate condition is still propitious to agricultural cultivation and the number of archeological sites increase heavily to 593.In addition,there are the least archaeological sites in the lake areas of southeast Hubei Province because of low-lying topography with altitude of 0-50 m and the severest flood.  相似文献   

10.
The study on 82 surface soil pollen samples from different types of cultivated vegetations in central and southern parts of Hebei Province indicates that the pollen assemblages from farmlands in the plain have not only their own plant types, but also the pollen components from the nearby mountains. Arboreal pollen percentages and concentrations (dominated by Pinus) from farmlands in mountain area are higher than those in the plain, and it reduces gradually with the increasing distance away from the mountains. Taking Pinus pollen in Taihang Mountains as an example, its content is 20%-30%, 10%-20%, 20%-30% and below 16% respectively for the samples from the area of 0-50, 50-100, 100-150 and more than 150 km away from the east Taihang Mountains. The increase of Pinus pollen proportion in the central plain is probably related to the fohn effect. The spatial variation of AP from mountains to the plain in Hebei Province may be similar to the forests clearance by human activities in the early historical period. Shrubby pollen proportion is small both in mountains and in the plain, but their major components are different. Elaeagnaceae, Corylus, Ostryopsis and Oleaceae are common in mountain areas, while there are relatively high contents of Rosaceae and Vitaceae in the plain. Herbs content in the plain (about 60%) is 15% higher than that in mountains, among which the Cereals and Cruciferae pollen percentages are 5% and 2% higher respectively. Artemisia pollen percentage in the plain is lower than that in mountains. Since the human activities are weaker in mountains compared with that in the plain, the general trend is that Chenopodiaceae pollen increases from mountains to the plain gradually, reflecting the raising intensity of human activities. The fern spores of Selaginella sinensis in mountains are higher than that in the plain, but it still reaches to about 7% in the plain. The fern spores of Selaginella sinensis are not prone to be spread by wind, indicating that those in the surface soil of the plain may be carried by river water from mountains during the deposition of the plain.  相似文献   

11.
中全新世仰韶文化扩张的环境背景   总被引:2,自引:0,他引:2  
黄河流域新石器文化在仰韶时期迅速扩张,由先前的以渭河流域为中心扩张到西至青海东部,东达黄河下游地区,北抵内蒙古长城一线,南至汉水流域的广大地区。全新世大暖期暖湿的气候条件与仰韶文化的迅速扩张关系密切。仰韶时期,黄土高原年均气温较现代高约2℃,年降水高出现代约100 mm,季风强劲,降水增加,400 mm等降水量线较现代向西北内陆推进200 km左右,黍粟作种植的范围扩大,仰韶文化相应扩张。400 mm等降水量线成为仰韶文化扩张的西界,也是全新世大暖期仰韶黍粟作种植区和北方细石器狩猎—采集区分界线。  相似文献   

12.
 在对渭河流域东部全新世黄土剖面磁化率、粒度、Rb/Sr、CaCO3等气候指标测定分析的基础上,结合已测定的光释光(OSL)年龄和古文化研究的最新成果,探讨了该区环境演变与人类古文化演进的历史及其相互关系。研究发现,在9.34~6.77 ka BP全新世最适宜的气候条件下,在7.80~7.30 ka BP出现了老官台文化,之后发育了仰韶早期文化;在全新世中期6.77~5.48 ka BP干冷气候初期出现了仰韶文化最繁荣的庙底沟类型文化;中后期随资源环境的持续恶化,该区出现了仰韶文化衰落的西王村类型文化;在全新世中晚期的5.48~3.12 ka BP气候再次发生好转推动了该区龙山文化的发展;4.60~3.76 ka BP期间频繁发生的洪水事件可能进一步强化了人地关系,并进而推动了该区文化进入夏商人类文明时期;3.12 ka BP以来趋于干冷的气候在推动该区人类文明进一步发展的同时,人类活动对环境影响的强度和范围也日益加大。渭河流域古文化得以延续发展至今,一方面说明气候环境的变化并未超越先民适应能力的范围,另一方面也说明渭河流域具有先民维持生存和发展的优越资源环境条件。  相似文献   

13.
中全新世甘青地区古文化变迁的环境驱动   总被引:6,自引:0,他引:6  
根据孢粉、古土壤和考古资料,结合甘肃、青海地区的地形特征,发现4 ka BP前气候温暖湿润,马家窑文化分布在黄河及其支流的森林草原河谷地区,东界在六盘山,向北则向河西走廊延伸,且主要从事种植业.4 ka BP后,由于气候环境的恶化,自然带向东迁移,生存环境演替为温带草原,齐家文化替代了马家窑文化.为适应自然环境的变化,甘肃、青海地区人类文化遗址也向东南低海拔地区转移,且产业结构中畜牧业比重显著增加.  相似文献   

14.
宋志军  刘黎明 《地理研究》2012,31(8):1399-1410
在城乡协调发展的背景下,本文以自然属性为基础分析了北京具有不同经济属性的5类耕地的空间结构。波谱分析显示,不同类型耕地的空间分布具有不同的周期,它们共同形成了距天安门约23~44km(近郊平原)、44~66km(远郊平原)、66~126km(山区)的耕地宏观空间结构。通过计算各类耕地的空间维数和Hurst指数,认为景观农田区、美化农田区、近郊山区22~47km圈层的耕地不具备分形特征;规模农田区、景观廊道带、中远郊山区48~126km圈层的耕地由于受城市发展、自然条件、距离等因素的影响具有明显的分形特征。总体上,北京不同类型的耕地处于一种离散、连续和具有共度性、没有公度性的融合状态。  相似文献   

15.
河南省史前人类遗址的时空分布及其驱动因子   总被引:2,自引:1,他引:1  
基于ArcGis10.0 平台分析了河南省史前时期的仰韶文化遗址和龙山文化遗址的空间分布、濒河性、空间集聚度等指标。结果显示,18.8%的仰韶期遗址分布在河流的1 km缓冲区内,而龙山期遗址只有16.5%,其濒河性呈减弱趋势。豫西山区、南阳盆地、颍河-淮河地区龙山期遗址的空间集聚度比仰韶期分别增加了0.006,0.016 和0.021,暗示龙山时期的自然条件逊色于仰韶期导致人类活动范围受到局限。遗址密度3-D分析表明,河南地区史前人类活动格局从仰韶期的“单核型”演化为龙山时期的“多核型”。这种空间格局的变化可能与5.4 kaBP降温事件相关,而且龙山期的气候特征与仰韶时期相比显得温凉、干燥,加之农业生产技术的进步和人口增加促使史前人类活动核心区从豫西山区向豫东平原和豫北平原地区扩散。同时4.0 ka BP前后河南地区的干旱、洪水、低温等自然灾害频发亦加速了人类活动范围的快速扩展,并且石家河、大汶口、关中等史前文化类型向河南地区的渗透,造成河南龙山文化类型的多元化和空间分布的复杂化。而全新世早期的裴李岗遗址和晚期的二里头遗址数目较少且均匀分布于嵩山两翼,初步推测环嵩山地区是河南史前文化的肇源地区。  相似文献   

16.
甘彩红  李阳兵  陈萌萌 《地理研究》2015,34(6):1259-1269
以三峡库区腹地奉节县的27个乡镇为例,应用网格分析技术,以1km×1km网格为单元,揭示了聚落与坡耕地资源之间的配置关系以及不同岩性区聚落-坡耕地耦合模式差异,并对研究区人地关系做了类型划分。结果表明:①奉节县27个乡镇聚落和坡耕地的空间分布表现出较强的空间趋同性,二者用地比、斑块等级大小高值都主要位于北部梅溪河河谷和中部长江河谷地区,低值主要分布于南部石灰岩地区;②坡耕地偏多型主要分布于砂岩区,坡耕地偏少型主要分布于石灰岩区,而坡耕地-聚落均衡型则表现出随机分布格局;③研究区坡耕地大量存在的原因主要归结于坡耕地基数大和坡耕地退耕难度大。受坡耕地分布的影响,坡耕地偏多型的土壤侵蚀较其他耦合类型严重;④27个乡镇人地关系划分为人地矛盾突出型、人地矛盾较突出型、人地矛盾较缓和型和人地矛盾缓和型四种类型,而人地矛盾较突出类型所占比重最大,面临着退耕压力和耕地压力突出的双重问题。  相似文献   

17.
鲁鹏  许俊杰  王霞  胡亚毅  王辉 《地理科学》2022,42(4):730-738
嵩山地区是华夏文明的重要发祥地,与早期人类活动关系密切的区域植被全新世演化研究也备受关注,孢粉分析是此类研究的重要手段。分析嵩山地区已有的16处地点的19套孢粉数据,梳理出区域晚更新世以来的植被演化历史。结果表明,10 ka B.P.之前,区域乔木花粉极少,为草地植被景观;10~7 ka B.P.,乔木花粉增多,丘陵、台地地区为疏林草地,平原地区乔木分布较多,为森林草地;7~5 ka B.P.,乔木花粉含量继续增加,丘陵地区仍为疏林草地,台地地区已经具有森林草地景观特征,平原地区则为针阔混交林植被景观;5~2.5 ka B.P.,乔木花粉含量逐渐减少,区域又转变为疏林草地植被景观。区域早期植被研究存在沉积样品孢粉含量少,地层年代分辨率低,自然沉积剖面较少,山地、丘陵区域数据不多等问题。未来研究需要有效引进信息技术,在孢粉提取与鉴定方法不断改进的基础上,开展多种地貌类型的高分辨率研究。研究思路也需要从孢粉数据重建气候演变向植被特征与人类活动交互作用所延伸。  相似文献   

18.
渭河流域全新世环境演变对人类文化发展的影响   总被引:2,自引:0,他引:2  
通过对渭河流域10000 多年来环境资源演变的高分辨率实验数据资料和考古文献资料的分析, 探讨了全 新世以来, 渭河流域人类文化的演进与环境演变之间的耦合关系。分析表明:在8 500~3 100 a B.P.全新世大暖期, 渭河流域水、土、生物资源条件优越, 人类逐步形成了原始定居旱作农业类型文化, 从而奠定了渭河流域农业文明 的基础; 其间4 000~3 000 a B.P., 渭河流域北部的农牧交错带, 由于气候的逐渐冷干化, 导致水、土、生物资源退化, 造成旱作农业土地利用方式由游牧业取而代之; 在3 100 a B.P, 由于季风格局的突变, 整个渭河流域进入了一个相 对干旱缺雨、成壤环境的恶化时期, 环境的恶化导致了水土资源的退化, 大大动摇了旱作农业和游牧业的经济基 础, 影响了先周和西周社会的发展。  相似文献   

19.
黄河源区生态环境退化研究   总被引:17,自引:2,他引:15  
生态环境退化是黄河源区所面临的重要的生态问题和社会经济问题。源区生态环境退化不但影响本区经济的可持续发展,而且对中下游地区的生态环境和水文条件构成很大威胁。在收集区内现有研究成果的基础上,通过对2000年TM影像的解译,对黄河源区生态环境退化现状和特征作了全面系统的研究。源区生态环境退化主要表现在冰川退缩、冻土面积的减小和冻融侵蚀面积的扩大,植被退化和土地退化的加剧等过程。最后,在分析未来气候变化和人类活动的基础上,对生态环境变化趋势作了预测。  相似文献   

20.
青海湖江西沟遗迹是青藏高原东北缘一处有连续地层的重要细石器文化遗存,对其人类活动指标(石器、动物碎骨、陶片等) 与环境指标(磁化率、色度、孢粉及集成结果) 对比分析表明:细石器文化与环境变化关系密切,在全新世JXG2 细石器狩猎者一直生活在以蒿为主的草原环境.在9 ka BP以前的早全新世,环境状况不断好转,人类已经在湖区活动,并逐渐增强;9 ka BP后最佳的水热组合,较高的草原覆盖,为细石器狩猎者提供充足的食物来源,推动文化进入鼎盛期;6 ka BP后随着环境干冷化,细石器文化也开始衰弱.孢粉分析发现9~6 ka BP高的禾本科含量及种类丰富的杂草花粉,与人类活动有关;尤其是禾本科含量在6.7~4 ka BP保持较高水平,此时段恰是陶片开始出现并普遍使用的时期,推测与JXG2 先民尝试种植农作物有关.高原东北缘在6 ka BP之前为细石器文化,6 ka BP之后高原史前文化开始发生分化,细石器狩猎者活跃在海拔较高的高原上,农业种植者占据了较低的河谷地带,在二者交接地带,形成了兼具细石器文化与农业种植文化特征土著新石器文化.  相似文献   

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