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1.
Effects of grazing and climate change on species diversity in sandy grassland, Inner Mongolia, China
To understand the effects of animal grazing activities and climate change on sandy grassland vegetation in northern China, a field grazing and protected enclosure experiment was conducted from 1992 through 2006 in Horqin Sand Land, Inner Mongolia. The results showed that (1) the grazing was primary responsible for changes of the vegetation richness and diversity in the grazing grassland and that changing climate was the main reason for changes in the species richness and diversity in the grassland protected from grazing; (2) light and moderate grazing can promote restoration of the richness and the diversity in the degraded grassland, and heavy grazing could result in a decrease of the richness and diversity; (3) heavy grazing can result in significant decrease of the perennial diversity, and moderate and light grazing promotes increase of the perennial diversity; the grazing, whether heavy or moderate and light grazing, was beneficial to increase of the annual diversity; (4) heavy grazing was not beneficial to diversity of Graminean and Chenopodiaceae, and moderate and light grazing was favorable the diversity of Compositae and Chenopodiaceae; (5) the warm-humid climate was favorable to increase of the richness and the diversity, and the warm-drought climate could result in decease of the richness and the diversity; (6) increased precipitation was favorable to perennial diversity and the diversity of Graminean, Leguminosae, and Compositae, and decreased precipitation had few effects on the annual diversity and Chenopodiaceae diversity. 相似文献
2.
长江中游马口-田家镇河段40年来河道演变 总被引：2，自引：1，他引：1
Quantitative analysis was performed on the filling-scouring process for the river reach within Makou and Tianjiazhen, the middle Yangtze River with the help of GIS and DEM techniques. The research results indicate that the river reach between Makou and Tianjiazhen was dominated by the scouring process, and the magnitude of scouring is increasing over time. The intensity of scouring process is more in the deep and narrower river reach than shallower and wider ones. The river reach in the Makou and Tianjiazhen river knot is in fre-quent scouring and filling process, however the river reach upper to the Makou and lower to the Tianjiazhen river knot is in moderate scouring and filling process. The river reach just upstream or downstream to the river knot (e.g. Makou and Tianjiazhen river knot in this research) is dominated by filling process and the river reach in the river knot is dominated by the scouring process. Research results indicate no changes in the boundary of the river but the scouring and the filling magnitude in specific river channel is strong. The filling and the scouring process of the study river reach is greatly impacted by the sediments and water from the upstream of the study river reach. The construction of the Three Gorges Dam just upstream to Yichang will cause further decrease of the release of the sediment load to the middle and the lower Yangtze River basin, which will further intensify the scouring process of the river channel in the study river reach. 相似文献
3.
In order to research the changing process of the pollution from the formation of Nansihu Lake, this study determined the isotope age and depositional rate and analyzed the organic geo-chemical quotas and heavy metal quotas of two sedimentary profiles of Weishan and Dushan lakes. Research results showed that from the formation of Nansihu Lake, the change of the pollution could be divided into four phrases. At the early phrase of the formation, the organic matters of the lake mainly derived from the exotic matters and had a close relation to the effect on the water and sands from the Huanghe (Yellow) River. At the middle and late phrases of the development, the endogenous matters of the lake became the main and stable source of the organic matters. The overflow of the Huanghe River, the excavation of the Grand Canal and the cut of trees caused the changes of the historic pollution. In recent 20 years, the modem industrial pollution from the organic matters and heavy metals has an increasingly heavy tendency. 相似文献
4.
Revealing ecosystem services relationships and their driving factors for five basins of Beijing 总被引：1，自引：1，他引：0
A clear understanding of the relationships among multiple ecosystem services(ESs) is the foundation for sustainable urban ecosystem management. Quantitatively identifying the factors that influence ES trade-offs and synergies can contribute to deepening ES research, from knowledge building to decision making. This study simulated soil conservation, water yield and carbon sequestration in Beijing, China, from 2015–2018. The spatial trade-offs and synergies of these three ESs within the five major river basins in Beijing were explored using geographically weighted regression. Furthermore, geographical detector was applied to quantitatively identify the driving mechanism of the environmental factors for the ES trade-offs and synergies. The results show the following:(1) the spatial relationships between soil conservation and water yield, as well as between water yield and carbon sequestration, were mainly trade-offs. There was a spatial synergy between soil conservation and carbon sequestration.(2) Regarding the spatial trade-off/synergy between soil conservation and water yield in Beijing, the dominant influencing factor was temperature/elevation, and the dominant interactions of the spatial trade-off and synergy between these two ESs in Beijing and the Chaobai River Basin are all manifested in the superposition of precipitation and potential evapotranspiration, temperature, and elevation.(3) Topographic factors were the dominant factors influencing the spatial relationship between soil conservation and carbon sequestration in Beijing and its five major river basins. As a result of the distribution of water systems and hydrological characteristics of the basins, differences were observed in the effects of different combinations of interaction factors on the spatial relationship between these two ESs in different basins.(4) Temperature had the strongest explanatory power in terms of the spatial trade-offs and synergies between water yield and carbon sequestration. The interactions between precipitation and temperature and between precipitation and elevation were the dominant interactions affecting the spatial relationship between water yield and carbon sequestration in Beijing. Overall, the explanatory power of influencing factors on the trade-offs and synergies and the degree of interaction between factors coexist in different basins with consistency and differences. Therefore, understanding the quantitative characteristics of basin-scale spatial trade-offs and synergies between ESs is important for ecosystem management and the promotion of synergy in different basins. 相似文献
5.
QIAO Lifang QI Anguo ZHANG Yichuan 《湿地科学》2008,6(1):80-86
The research of ecology and landscape reestablishment of river floodplain is considered favorable to its conservation and development.The similarity and difference among river floodplain,wetland,riverside and shore have been reviewed,as well as the progress in the research of floodplain ecology reestablishment in quantitative evaluation,vegetation restoration,the influence on animal habitat and the application of eco-engineering;and of the landscape reestablishment in resource development and utilization,landscape feature and changes,landscape function,structure and control.The potentially important fields are expected to be the change of landscape pattern in different scales,the reasonable protection and utilization in the floodplain tourism,the simulating and monitoring of landscape dynamics,the planning and designing methods of floodplain landscape and the management of floodplain ecosystems. 相似文献
6.
ZHU Bingqi YU Jingjie QIN Xiaoguang Patrick RIOUAL LIU Ziting XIONG Heigang 《地理学报(英文版)》2014,24(1):177-190
Sandy desert landscape is a geological product of arid climate and abundant sand materials supply in natural conditions, therefore the formation of sandy desert is an ideal studying object for understanding the interaction between various stratigraphic/epigenetic spheres of the earth system. However, until now, the knowledge about the provenance and formation of these deserts in Xinjiang, Central Asia is diverse and inconsistent, a systematic review is necessary. Ancient aeolian sand sediments in the internal areas of these deserts and their twin dust deposits in the Cenozoic strata surrounding the Xinjiang deserts are direct and indirect clues reflecting the provenance of sand materials and the formation and evolution of deserts. Based on the geochemical, mineralogical and isotopic evidences of desert sands and relevant deposits in the peripheral regions, this paper reviews the research progress on the development of the sandy deserts in Xinjiang, Northwest China. Many proofs proposed that desert sands in Xinjiang were mainly sourced from the ancient pluvial, alluvial and fluvial sediments and were eventually achieved because of the local sand supply. It pointed out that the settings of tectonic structure in Xinjiang had made sediments both in the Tarim Basin and the Junggar Basin being influenced greatly by regional hydrological system and aeolian processes originated from the planetary wind system of westerly, the East Asian winter monsoon and the topographical mountain-valley winds. However, the directions of transpor- tation paths are different between the hydrological dynamics and the aeolian dynamics, which are decided by the slantwise structures of the basins tectonics and the regional atmospheric circulation routes, respectively, and have determined anisotropies of the transport pathway of these sediments delivered by different agents. This results in a geological cycle of detrital sediment transportation in the two large sediment mixing, alternation and recycle basins and thus largely increases the degree of between younger and older sediment sources, as well as the complexity and diversity of sand provenances. 相似文献
7.
榆林地区土地退化机制和调控 总被引：6，自引：0，他引：6
Yulin district is located in the transitional zone between Mu Us Desert and Loess Plateau of northern Shaanxi Province,thus it is particularly vulnerable to degradation due to its fragile ecosystem and intense human activites there,The purpose of hias study is to explore the mechanism,process and driving force of land degradation in area with vulnerable eco-environment within the context of increasing population and intensifying human economic activities,and then find out the patterns and countermeasures of how to control them using the economic and technological ways,In detail ,this study includes three main sections:the first section analyzes the mechanism,causes and characteristics of land degradation,which can be achieved by the typical field investigations and systematical analysis within the regional natural,social and econmomic context.Based on the technologies of remote sensing and GIS ,and combined with the modeling methods,the second section reveals the change characteristics of land use and its driving force from 1990 to 2000; AS to the third section ,feasible countermeasures of how to prevent the degradation and rehabilitate the regional ecology are propsed ,which are studed from the perspective of harmony between nature and economy,and the conception of regional sustainable development. 相似文献
8.
Physical geography and human geography are the principal branches of the geo-graphical sciences. Physical process simulation and human process simulation in geography are both quantitative methods used to recover past events and even to forecast events based on precisely determined parameters. There are four differences between physical process simulation and human process simulation in geography, which we summarize with two spe-cific cases, one of which is about a typhoon’s development and its precipitation, and the other of which is regarding the evolution of three industrial structures in China. The differences focus on four aspects: the main factors of the research framework; the knowledge back-ground of the systematic analysis framework; the simulation data sources and quantitative method; and the core of the study object and the method of forecast application. As the hu-man-land relationship is the key ideology of the man-land system, the relationship between the physical and human factors is becoming increasingly close at present. Physical process simulation and human process simulation in geography will exhibit crossing and blending in the future to reflect the various geographical phenomena better. 相似文献
9.
The data from the Southern Ocean observations of World Ocean Circulation Experiment(WOCE) are used for analysis and illustration of the features and spatial distributions of Circumpolar Deep Water(CDW) in the southern Indian Ocean.It is learnt from the comparison among the vertical distributions of temperature/salinity/oxygen along the 30°E,90°E and 145°E sections respectively that some different features of CDW and the fronts can be found at those longitudes,and those differences can be attributed to the zonal transoceanic flow and the merizonal movement in the Circumpolar Deep Water.In fact,the zonal transoceanic flow is the main dynamic factor for the water exchange between the Pacific Ocean and the Indian Ocean or between the Atlantic Ocean and the Indian Ocean,and for the effects on the spatial distributions of the physical properties in CDW. 相似文献
10.
Energy consumption has an inevitable connection with economic level and climate. Based on selected data covering annual total energy consumption and its composition and that of all kinds of energy in 1953-1999, the annual residential energy consumption and the coal and electricity consumption in 1980-1999 in China, the acreage of crops under cultivation suffered from drought and flood annually and gross domestic product (GDP) in 1953-1999 in the whole country, and mean daily temperature data from 29 provincial meteorological stations in the whole country from 1970 to 1999, this paper divides energy consumption into socio-economic energy consumption and climatic energy consumption in the way of multinomial. Itchanges between the climate energy consumption andalso goes further into the relations and their changes between the climate energy consumptionenergy consumption and the economic level inand climate factor and between the socio-economic energy between the climate energy level in China with the method of statistical analysis. At present, there are obvious transitions in the changing relationships of the energy consumption to economy and climate, which comprises the transition of economic system from resource-intensive industry to technology-intensive industry and the transition of climatic driving factors of the energy consumption from driven by the disasters of drought and flood to driven by temperature. 相似文献
11.
40 kaBP来亚非季风演化趋势及青藏高原泛湖期 总被引：8，自引：1，他引：7
基于18个黄土/古土壤序列 (黄土高原与青藏高原) 与27个湖泊沉积序列 (青藏高原、新疆、云南与赤道非洲及其以北的非洲季风区) 对比分析了东亚季风区、印度季风区与非洲季风区40 ka以来的区域环境演变特征。结果显示：上述区域在对应岁差周期的高太阳辐射阶段,也就是40~24 kaBP与14~4 kaBP分别经历了一次环境湿润期,而在末次冰期最盛期,除中国云南、青藏高原及新疆部分地区外,其他地区则较为干燥。青藏高原及其北侧的新疆区,40~24 kaBP比14~4 kaBP气候更为湿润,湖泊呈现40 ka以来的最高最大湖面,高原进入一次泛湖期。而非洲区及黄土高原,则与此相反;14~4 kaBP气候比40~24 kaBP更为湿润、适宜,湖面更高,成壤作用更强。40~24 kaBP,印度季风强盛,加强了对高原的水汽与潜热输送,同时,由于北方冰盖的存在,西风气流则相对南移,增加了对高原的影响,两种气流交互作用引起的强降水,可能是造成湖泊显著扩张的主要原因。 相似文献
12.
黄土高原晚更新世末次冰期时期,冬季风强盛,马兰黄土堆积;全新世以来的间冰期时期,夏季风强盛,降水较丰,侵蚀强烈。晚更新世以来的中国东部海岸线40°N 一带变化最大,同纬度晋陕蒙接壤区是黄土高原季风气候变化最剧烈的地区,致使该区成为黄土高原沙黄土区中现代降水最多的地区。沙黄土和较多降水的组合,使晋陕蒙接壤区成为黄土高原现代侵蚀最剧烈的地区。 相似文献
13.
南京下蜀黄土红外释光地层年代学 总被引：7，自引：1，他引：6
下蜀黄土地层年代学对于理解季风环流时空格局演化及其与青藏高原阶段性隆升的关系十分重要。作者基于下蜀黄土红外释光测年和下蜀黄土及黄土高原洛川;剖面磁化率序列的对比分析,认为下蜀黄土第一层黄土层形成于末次冰期,最底部的黄土层与洛川的 L5相当。因而下蜀黄土应相当于黄土高原LS以来的风成堆积,其底界年代约为 500 ka。也就是说,在 500 ka左右黄土堆积的南界已达长江下游地区。这可能是因为其时青藏高原的隆升已到达一特殊高度,对东亚季风演化的影响成为一个转折点,加强了东亚季风的强度。 相似文献
14.
基于石笋记录的云贵高原古气候变化研究进展 总被引：1，自引：0，他引：1
重建古气候、古环境已成为当今全球变化研究的热点.石笋作为岩溶洞穴次生化学沉积物的典型代表,是古气候研究的重要载体.基于近年来已报道的贵州荔波、茂兰、都匀凯口及云南寻甸、宣威、宁蒗等地11个洞穴30余根石笋的氧同位素数据的综合分析,认识云贵高原163 kaBP以来的古气候变化情况.结果表明,163kaBP以来,青藏高原隆升对全球气候格局的改变及季风系统的形成起到重大影响,在此大背景下,云贵高原气候演变体现了全球一致性,也呈现出其自身规律：（1）倒数第2次冰期的冰盛期（163.3～ 129.28 kaBP）,气候严寒干冷,期间伴随温凉向冷干的转变;（2）末次间冰期（129.28～78.92 kaBP）,气候温暖湿润,但期间冷暖波动变化幅度很大;（3）末次冰期（78.92～11.2 kaBP）,气候极不稳定,冷暖波动很大,总体呈现降雨由多变少,气温由高变低的变化趋势;（4）全新世（11.2 kaBP至今）,气候温暖,雨量充沛,气候呈现变暖—高温—稍变冷—恢复的变化趋势.云贵高原作为一个特殊区域,即东亚季风与印度季风的过渡带,对研究中国甚至于全球季风系统的演变发展有着重要意义.通过多指标多手段,提高研究区研究精度,拟建古气候变化曲线,应对全球变暖的区域性实证研究及未来气候模拟预测将是今后努力的方向. 相似文献
15.
对陇西盆地六盘山西侧山麓剥蚀面上断岘剖面的古地磁、磁化率和粒度分析表明,该剖面具有1.8 M a B.P.以来完整的黄土-古土壤沉积序列。断岘剖面以下7级黄河阶地的发育形成以及在1.1和0.8 M a B.P.前后所指示的腾格里沙漠扩张变化,反映了第四纪早更新世以来青藏高原阶段性隆升对黄土高原西部环境变化影响,以及在青藏高原隆升过程中构造与气候的变化与耦合响应。 相似文献
16.
13 ka BP 以来黄土高原西部的植被与环境演化 总被引：2，自引：0，他引：2
通过对黄土高原西部三个剖面的孢粉记录分析, 重建了该区13 ka BP 以来详细的植被 与气候演化序列。结果表明, 12.1 ka BP 以前, 研究区植被以干草原为主, 气候寒冷干燥。 12.1~9.8 ka BP 植被变化显著。期间出现两次显著的湿润期, 分别为12.1~11.4 ka BP、 11.2~11.0 ka BP, 可与博令暖期和阿勒罗得暖期对比; 两次持续时间和强度明显不同的干旱 期出现在11.4~11.2 ka BP 和11.0~9.8 ka BP, 可分别与中仙女木事件和新仙女木事件对比。 经过短暂的快速变湿后, 9.6~7.6 ka BP 研究区植被以疏林草原为主, 气候波动频繁但总体温 和偏干。7.6~4.0 ka BP 森林和森林草原植被出现, 气候温暖湿润。其中6.6~5.8 ka BP 温带落 叶阔叶林发育, 为研究区全新世最适宜期。自4.0 ka BP 以来研究区草原和荒漠草原交替出 现, 气候在总体干冷的环境下存在次一级的干湿波动。 相似文献
17.
Pollen records from the Chinese Loess Plateau revealed a detailed history of vegetation variation and associated climate changes during the last 13.0 ka BP.Before 12.1 ka BP,steppe or desert-steppe vegetation dominated landscape then was replaced by a coniferous forest under a generally wet climate(12.1-11.0 ka BP).The vegetation was deteriorated into steppe landscape and further into a desert-steppe landscape between 11.0 and 9.8 ka BP.After a brief episode of a cool and wet climate(9.8-9.6 ka BP),a relati... 相似文献
18.
泾河中游地区全新世成壤环境演变研究 总被引：13，自引：7，他引：6
根据长武ETC全新世土壤剖面的测定分析,探讨了该地区全新世成壤环境演变过程,阐明了先周时代土壤特征及人类耕作对成壤过程的影响。研究结果表明,全新世早期气候温和干燥,沙尘暴明显减弱,风尘堆积速率降低,具有轻微生物风化成壤作用;对应于全新世最适宜期,该地气候温暖湿润,生物风化成壤作用大于风尘堆积作用,为典型的黑垆土成壤期。从3 100 a B.P.开始,季风气候格局发生转变,气候干旱化,沙尘暴加剧,风尘堆积速率大于生物风化成壤速率,土壤资源自然退化,形成弱成壤层和黄土层,两层均属于全新世黄土L0。先周时期耕作层对应古土壤层的顶部,土壤具有典型的团粒结构。3 100 a B.P.时的季风转变导致的气候干旱化与土壤退化促使了游牧民族南迁和"古公迁岐"事件的发生。 相似文献
19.
黄土高原侵蚀期研究 总被引：22，自引：12，他引：10
黄土高原在沉积的同时也存在着侵蚀,主要是流水、重力等因素造成的。这种侵蚀会受到气候、构造运动以及人类活动控制。资料显示,黄土高原存在3种基本的侵蚀期,一是气候侵蚀期,二是构造侵蚀期,三是人为因素侵蚀期。此外还有气候与构造共同作用产生的侵蚀期和构造与人类共同作用产生的侵蚀期。温湿期风尘堆积少,降水量增多,流水动力增强,是黄土高原理论上的侵蚀期。构造抬升引起侵蚀基准面下降,进而导致黄土高原加快侵蚀,出现构造侵蚀期。人类活动破坏了黄土高原的植被和土层结构,导致黄土高原侵蚀加剧,从而出现了人类因素引起的现代侵蚀加速期。在黄土发育的冷干期,由于植被稀疏,侵蚀量大于温湿期,但堆积量远大于侵蚀量。要改变现代侵蚀状况,就应当加强黄土高原生态环境治理。 相似文献
20.
泾河上游黄土高原全新世成壤环境演变与人类活动影响 总被引：10，自引：1，他引：9
通过对黄土高原腹地甘肃合水MJY-A全新世土壤剖面磁化率、粒度、全铁、TOC、TC、CaCO3等气候代用指标的测定分析。结果表明：在全新世早期,黄土高原中部地区气候虽比较温和干燥,风尘堆积速率降低,土壤发育表现为边沉积边成壤的自然过程;到了全新世中期,气候较为温暖湿润,地表植被发育,生物风化成壤作用强烈,土壤发育依旧表现为自然的成壤过程,形成深厚的古土壤-黑垆土(S0);到了全新世晚期,气候开始恶化,干旱少雨,植被急剧退化,沙尘暴频繁发生,形成的现代黄土层(L0)覆盖了土壤(S0)使之成为埋藏古土壤,土壤发育深受人类活动的影响。现代黄土高原土地资源的退化,并不全是由自然要素本身固有的规律所造成的,而是在自然要素本身变化的背景上叠加了人类活动影响的结果。 相似文献