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1.
布古里沙漠位于喀什绿洲和叶尔羌河绿洲之间,具有独特的地貌特征和风沙环境特征。通过对布古里沙漠部分地区的气象资料分析和野外实地风沙观测,对其风沙环境特征进行了分析。结果表明：布古里沙漠的沙粒平均粒径是0.16 mm,起沙时间集中在每年的4～9月,风向主要是西北风和东北风,偏西北风略强;在2 m高处测量的裸露沙面起动风速的是3.0 m/s,植被覆盖率为7%,起动风速为5.2 m/s,植被覆盖率为14%,起动风速为6.8 m/s;当平均风速为6.7 m/s时,气流输运沙子主要在近地表面0～10 cm,,风沙流中含沙量随垂直高度呈指数衰减,给出了风沙流的含沙量随垂直高度分布的相关方程和参数。 相似文献
2.
基于作物空间分配模型的东北三省春玉米时空分布特征 总被引：3，自引：0，他引：3
利用1980-2010 年东北三省分县玉米播种面积与产量统计、耕地分布、农业灌溉分布以及作物适宜性分布等多源数据,结合基于交叉信息熵原理的作物空间分配模型（Spatial Production Allocation Model,SPAM）,在5'×5'的像元尺度模拟了春玉米种植面积与产量的时空分布,并重点分析了两者在纬向、经向,以及高程上的时空变化规律。结果显示：（1）玉米种植面积在2000 年前向北扩展至北纬44°~48°间,2000 年后在中南部出现大规模发展（北纬42°~44°）,并进一步向东扩展至东经123°~127°间,同时还表现为向低海拔（高程100 m以下）和较高海拔（高程200~350 m）扩展的态势;（2）单产在纬向上的增加区主要集中在北纬42°~48°,经向上的单产增加则相对均匀,高程上单产提升区主要集中在海拔350 m以下。（3）像元内玉米种植比例整体上由中低种植比例为主逐步演变为中高比例占据主体,并且中高种植比例像元对应的玉米单产水平整体上较高,反映了市场经济驱动下的玉米种植集聚化和规模化的发展趋势。 相似文献
3.
GIS goes nano: Vegetation studies in Victoria Land, Antarctica 总被引：1，自引：0，他引：1
Abstract: Vegetation in Antarctica consists mainly of algae, moss and lichen and is interesting to research because of the isolation and extreme growing conditions. An understanding of this vegetation is important for both the management of tourism in Antarctica, and because it provides a potential barometer of global climate and environmental change. This paper demonstrates two applications of GIS to mapping vegetation in Victoria Land, Antarctica. The first application computes the changes that have occurred to the vegetation within a 120 m by 28 m plot between 1962 and 2004. The second application maps and analyses the growth of a lichen specimen (Buellia frigida) during the same period. These applications demonstrate that GIS is a multiscale technology that can be used to detect detailed change in vegetation growth. 相似文献
4.
David Palacios & Manuel García Sánchez-Colomer 《Geografiska Annaler: Series A, Physical Geography》1997,79(1-2):25-40
This article examines how snow plays a role in current erosive processes in a high mountain area (1800—2400 m a.s.l.) known as Peñalara, located in Spain's Central Range (40°50' N; 3°58' W). The hypothesis maintains that snow becomes an important erosive factor when it accumulates over sedimentary or weathered materials, therefore geomorphological heritage is a key factor in nival erosion. To test this hypothesis, the authors identified the landforms in the study area and determined their relative ages by weathering and lichenometry ( Rizocarpon geographicum ag. ), differentiating between preglacial, glacial (Recent Pleistocene) and postglacial (Holocene) forms. The information was used to plot a reticulate pattern of observation sites for the study area. Snow depth and the movement of selected blocks at each site were recorded from October 1991 to June 1995. The relationship between late-lying snowpatches, geomorphological heritage and current erosive processes was determined. Between 1800 and 2000 m a.s.l., there is an indirect relationship between snowpatches and predominant processes (stream incision and gelifluction) on terminal moraines. Between 2000 and 2200 m, direct action is present where there are late-laying snowpatches on lateral moraines and some glacial steps. Between 2200 and 2400 m, gelifraction and gravity processes are also in direct relation to snowpatches. 相似文献
5.
从艾比湖两岸大致沿同一经度分别向南北山前地带,对39个样地进行野外调查和样品采集。通过研究植被结构和土壤性质的变化特征,探讨了植被-土壤在南北两断面上的差异。结果表明：两地植被存在群落中优势种群类型、数量、长势及其空间分布的差异,而多样性指数及植被盖度的统计学差异并不显著;土壤的粒度平均水平明显不同,而粒度的离散性及对正态的偏离度仅在表层差异显著;多种养分含量差异均显著;土壤表层、次表层含水量、含盐量（包括盐分主要离子含量）和pH的平均水平及变化程度,南北差异的显著性不一致,但整体上看,仍属于比较明显的范畴。这些差异是艾比湖南北地形、水文、气象、物源明显不同的结果,也是植被和土壤耦合作用的结果。 相似文献
6.
Ice flow physical processes derived from the ERS-1 high-resolution map of the Antarctica and Greenland ice sheets 总被引：1，自引：0，他引：1
Frédérique Rémy Philippe Shaeffer & Benoît Legrésy 《Geophysical Journal International》1999,139(3):645-656
The ERS-1 satellite, launched in 1991, has provided altimetric observations of the Greenland Ice Sheet and 80 per cent of the Antarctica Ice Sheet north of 82°S. It was placed in a geodetic (168-day repeat) orbit between April 1994 and March 1995, yielding a 1.5 km across-track spacing at latitude 70° with a higher along-track sampling of 350 m. We have analysed the waveform altimetric data from this period to compute maps with a 1/30° grid size. Data processing consists of correcting for environmental factors and editing and retracking the waveforms. A further step consists of reducing the radial orbit error through crossover analysis and correcting the slope error to second order. The high-resolution topography of both ice sheets reveals numerous details. A kilometre-scale surface roughness running at 45° from the flow direction is the dominant topographic characteristic of both continents. Antarctica also exhibits many scars due to local flow anomalies. Several physical processes can be identified: abrupt transitions from deformation to sliding and vice versa, and impressive strike-slip phenomena, inducing en echelon folds. 相似文献
7.
本文研究了北极巴罗 (Barrow)地区 1 2种冻原植物的花粉形态 ,它们的形状有球形、近球形、扁球形茧形和四合体型 ,其萌发孔有三孔沟、三沟、二合沟以及散孔等类型。花粉具辐射对称和两侧对称两种类型。这些花粉的植物体是北极冻原地区常见的植物 ,分属于 1 2个科 ,除 3种为小灌木外 ,大多数为多年生或一年生草本植物。这些冻原植物花粉形态的研究为恢复北极地区古植被和古气候的研究 ,提供了有价值的对比资料和依据。 相似文献
8.
BY JULIO MUÑOZ JIMÉNEZ ARTURO GARCÍA ROMERO 《Geografiska Annaler: Series A, Physical Geography》2009,91(3):189-204
The purpose of this study was to determine plant distribution at a nivation hollow located in a Mediterranean high mountain area and to analyse the effects of snow cover, wind exposure, proximity to moisture and the characteristics of the substrate on the vegetation. We analyse these factors and interpret concurrent effects due to recent climate change.
The nivation hollow, called Ventisquero de la Condesa, is located at 2258 m a.s.l., 40°47'10"N and 3°58'35"W, in the Sierra de Guadarrama (Madrid, Spain). We established 579 small sample plots in the study area, and grouped them into 29 transects where snow duration, wind exposure, availability of meltwater, geomorphologic instability and surface rockiness were examined directly and indirectly. The types of plants and the number of individuals per species were registered for each plot to establish ecological affinities among the 28 distinguishable species. Six showed the highest level of chionophily while nine showed the lowest adaptation to snow cover duration. A statistical study incorporating other variables applied in the research revealed that wind exposure, moisture capture and the intensity of geomorphologic dynamics have a highly significant correlation with nivation, while surface rockiness is a virtually independent factor. Due to environmental changes caused by recent global warming, several plant species, especially adapted to survival in snow conditions, coexist in the hollow with saxicolous plants that have invaded the site from adjacent grass and shrublands. 相似文献
The nivation hollow, called Ventisquero de la Condesa, is located at 2258 m a.s.l., 40°47'10"N and 3°58'35"W, in the Sierra de Guadarrama (Madrid, Spain). We established 579 small sample plots in the study area, and grouped them into 29 transects where snow duration, wind exposure, availability of meltwater, geomorphologic instability and surface rockiness were examined directly and indirectly. The types of plants and the number of individuals per species were registered for each plot to establish ecological affinities among the 28 distinguishable species. Six showed the highest level of chionophily while nine showed the lowest adaptation to snow cover duration. A statistical study incorporating other variables applied in the research revealed that wind exposure, moisture capture and the intensity of geomorphologic dynamics have a highly significant correlation with nivation, while surface rockiness is a virtually independent factor. Due to environmental changes caused by recent global warming, several plant species, especially adapted to survival in snow conditions, coexist in the hollow with saxicolous plants that have invaded the site from adjacent grass and shrublands. 相似文献
9.
In situ terrestrial cosmogenic nuclides(TCN) have been widely applied to date the ages of Quaternary glacial deposits in Antarctica and plays an important role in reconstructing the glacial evolution and climate change. It helps to understand the Antarctic ice sheet's evolution process in Quaternary and shed light on the application of Cosmogenic Nuclide exposure dating technique in glacial geomorphology. In this paper, we retrieved 49510 Be age samples in Antarctica from literature published between 2004 and 2020 and recalculated the TCN ages using version 3.0 online calculator of Cosmic-Ray Produced Nuclide Systematics on Earth(CRONUS-Earth). Several conclusions can be drawn from the results:(1) 75% of the exposure ages are younger than 400 ka, and 91% younger than 1, 100 ka. Northern Antarctic Peninsula exposure result is visibly younger than the main glaciers area in East Antarctica due to climate change and geological evaluation since the LGM(Last Glacial Maximum).(2) TCN ages are relevant to the samples' relative positions in the Antarctic continent, but a relationship between their ages and elevations is yet to be determined based on the collected data. 相似文献
10.
沙冬青是我国珍稀濒危物种,掌握其地理分布范围及生境特征,有助于分析其所处境况以及展开相应的研究与保护工作。通过搜集历史文献资料与野外实地调查相结合的方法,对我国沙冬青属植物的地理分布范围、时空动态以及生境特征进行了研究,并从地形、气候、土壤三个方面探讨了限制沙冬青属植物生长分布的主要因子。结果表明：（1）新疆沙冬青分布范围为38°55'~40°09'N,74°42'~76°43'E;蒙古沙冬青分布范围为36°27'~42°01'N,102°36'~108°49'E,两种沙冬青在地理分布上不连续,以条带或块状方式呈现小聚集分布状态。（2）两种沙冬青的生境特征存在显著差异,其中限制新疆沙冬青分布的生态因子主要包括气候指标中的热量因子以及土壤指标中的pH、盐分和全磷,限制蒙古沙冬青分布的生态因子主要包括气候指标中的水分因子和土壤指标中的有机质、全氮。 相似文献
11.
H. Motoyama K. Kamiyama M. Igarashi F. Nishio & O. Watanabe 《Geografiska Annaler: Series A, Physical Geography》2000,82(1):33-38
10 m and 2.3 m ice cores were obtained on Austre Brøggerbreen, Spitsbergen in Svalbard (78°53 ' N, 11°56 ' E, 450 m a.s.l.) in September 1994 and in March 1995, respectively. Stratigraphy, bulk density, pH, electrical conductivity, and major ions were obtained from the core samples.
The chemical effect of meltwater percolation through snow/ice is examined. Good correlation between Cl− and Na+ was obtained. The ratio of Cl− to Na+ was 1.14 which was nearly the same value as in bulk sea water. However, the variation of Cl− /Na+ shows that higher ratio occured in the bubble-free ice. Furthermore the Cl− ions remain in higher concentration than SO 4 2− or Na+ ions. 相似文献
The chemical effect of meltwater percolation through snow/ice is examined. Good correlation between Cl
12.
塔里木河下游植物调查最小取样面积分析 总被引：3，自引：0，他引：3
采用巢式样方法,对塔里木河下游两个断面6条样带38块64 m×64 m样地进行调查,选用线性和非线性种-面积模型,对调查区不同比例因子植物调查最小取样面积、最小取样面积与不同地下水条件的关系进行了分析。根据种-面积曲线的最优模型,当比例因子取值包括群落50%、60%、70%、80%和90%的植物种类时,最小调查样地面积分别为418 m2、707 m2、1 138 m2、1 702 m2和2 656 m2;随着离河距离增加,物种数减少,植物的生长势降低。当比例因子取值包括群落50%植物种类、地下水埋深由离河50 m的1.57 m到离河1 500 m的7.53 m变化时,离河不同距离各级最小取样面积变化较大,地下水条件是植物种类调查最小取样面积变化的关键因素。 相似文献
13.
The Gulf of Aqaba earthquake swarm of 1983 January-April 总被引：2，自引：0，他引：2
Summary. In the period 1983 January 21 -April 20, more than 500 local earthquakes ( M L ≤ 4.85) occurred in the Gulf of Aqaba area between latitudes 29°00'and 29°25'and longitudes 34°30'and 34°45'. Most of the activity including the largest shocks was restricted to the area between latitudes 29°07'and 29° 15'and longitudes 34°33'and 34°42'where the NW Atiya regional dyke crosses the area and is horizontally displaced by NE strike-slip faults. The first-motion directions of four large shocks, including the largest, at both UNJ and HLW stations are in agreement with a strike-slip mechanism at a NE-trending fault in this area. The b value showed a temporal increase with time from 0.43 to 0.69. This, together with other geological and geophysical observations may indicate that subsurface magmatic activity has affected the stressed crustal rocks, thus triggering earthquake activity.
This swarm and historical information indicate that the Gulf of Aqaba-Dead Sea Jordan transform is characterized by both swarm and foreshock-aftershock types of seismic activity and therefore the relatively large proportion of non-seismic slip along the southern part of this transform may actually be higher if swarm-type activities are considered. 相似文献
This swarm and historical information indicate that the Gulf of Aqaba-Dead Sea Jordan transform is characterized by both swarm and foreshock-aftershock types of seismic activity and therefore the relatively large proportion of non-seismic slip along the southern part of this transform may actually be higher if swarm-type activities are considered. 相似文献
14.
青海湖环湖地区草地植被生物量遥感监测模型 总被引：57，自引：0，他引：57
利用青海湖环湖地区2000年陆地卫星TM遥感图像数据和同期野外实测的34处样方产草量数据,分析了遥感植被指数与草地植被生物量之间的相关关系,进而分别建立了遥感植被指数与草地植被生物量的一元线性回归模型和非线性回归模型。研究表明,遥感植被指数与草地生物量之间存在较好的相关性,但不同遥感植被指数与草地植被生物量相关性程度存在一定差别。此外,所建遥感植被指数与草地植被生物量的非线性回归模型在拟合精度上优于一元线性回归模型,且由三次方程得到的非线性回归模型最适用于监测青海湖环湖地区的草地植被生物量。 相似文献
15.
南极罗斯海恩克斯堡岛(Inexpressible Island)是中国南极新建考察站重点预选区域。本文利用1988—2012年曼努埃拉自动气象站(AWS Manuela)资料统计分析了该岛的气温、相对湿度、气压和风速风向等要素的特征和变化趋势。结果表明,该岛多年平均气温为-18.5℃,年平均气温有降低趋势;多年平均相对湿度较低,仅为45%,但春夏秋冬各季节的平均湿度均有增加趋势;多年平均气压为979.7hPa,无显著变化趋势;该站点多年平均风速为12.0 m·s-1,风向以WNW为主。干冷的下降风为该岛风场的主要特征,强下降风事件多发生在冬季(49.8%),其风速在25—45 m·s-1之间,冬季单次强下降风事件的平均持续时间达10 h以上。和中山站相比,该站点气温更低、空气更干燥、风速更大,这对该岛的越冬考察活动将带来巨大挑战。 相似文献
16.
柴达木河都兰区植被覆盖率变化特征 总被引：1，自引：0，他引：1
柴达木河都兰区位于青海柴达木盆地东南部,干旱少雨,生态环境脆弱。基于MODIS NDVI数据,应用遥感方法,对都兰区2000—2011年的植被覆盖率进行了计算,并分析了其影响因素。结果表明：研究区内裸土和低覆盖率植被的面积逐年减小,而较低覆盖率、中等覆盖率、较高覆盖率及高覆盖率植被的面积均逐年增加;研究区植被覆盖率与降水及相对湿度呈正相关关系,区域植被生长与地下水埋深的关系较为密切;宗加-诺木洪植被区的地下水埋深范围为0.7～3.5 m,在水埋深为1.7 m的地方,植被长势最好;当研究区的地下水水质矿化度小于3 g·L-1时,植被发育较好。 相似文献
17.
长白山区植被生长季NDVI时空变化及其对气候因子敏感性 总被引：7，自引：1，他引：6
本文利用长白山区SPOT/VGT NDVI 数据和气象数据,分析该区不同植被类型NDVI时空变化特征以及与气候因子的相关关系,并探讨了植被对气候变化响应的滞后性。结果表明：①2000-2009 年,长白山区植被NDVI 逐年变化总体呈增长趋势,增长区域的面积占全区面积的83.91%,在空间上主要集中在北坡和西坡,NDVI减少区域集中在南坡;②NDVI变化率随季节和植被类型变化而不同,NDVI增长主要集中在5 月和9 月,而7 月NDVI变化较小,甚至出现下降趋势;③植被NDVI与温度和降水存在着显著的正相关性（p<0.01）,且NDVI与温度的相关性高于与降水的相关性,且随海拔升高,NDVI与温度相关性增强;④NDVI对气温和降水变化的响应存在滞后期, 不同植被类型,滞后期存在差异。苔原NDVI对温度和降水响应的滞后期大约10 天,而针阔混交林和针叶林NDVI 对温度和降水响应的滞后期约为20 天。 相似文献
18.
泾河流域上游景观尺度植被类型对水文过程的影响 总被引：1，自引：1，他引：0
选择具有土石山区的泾河流域上游为研究对象,应用生态水文模型SWIM对上游景观尺度下各植被类型水文效应进行了模拟,并针对上游土石山区和黄土区分海拔段进行了植被分布的水文格局影响分析。结果表明：泾河流域上游的森林、农田、草地各植被类型的蒸散及组分、径流深和土壤深层渗漏各水文过程具有显著差异,不同区域（土石山区和黄土区）的同一植被类型的各水文过程明显不同;同时,植被景观格局存在区域和海拔差异,这使得不同区域和海拔段的各水文过程有所不同。如在土石山区,以森林为主的海拔段2 250-2 922 m降水量和蒸散量均最大（分别为641 mm和484 mm）,以农田、草地和森林均有分布的海拔段1 750-2 250 m降水量较大（590 mm）,但蒸散量最低（仅为434 mm）;而在较为干旱的黄土区（降水量为514 mm）以农田和草地为主两个海拔段（1 026-1 350 m和1 350-1 750 m）的蒸散量较高（分别为458 mm和440 mm）。另外,从各水文过程要素与降水的比值看,两个区域之间差异比较明显,但同一区域不同海拔段间差异不明显。 相似文献
19.
绿洲-荒漠交错带防护林与自然植被的协同防风效能及优化模式探讨 总被引：2，自引：0，他引：2
以新疆准噶尔盆地南缘绿洲-荒漠交错带为研究区,研究了该区防护林与其外围自然植被的协同防风效能,进而构建了二者协同配置的优化模式。结果表明:①在有障碍物(防护林、自然植被)存在时,风表现出显著的规律性,即在0.5 m和1.5 m高度处,防护林与自然植被协同后对风速起到了减弱作用。对于疏透结构林带,风速的减弱程度为自然植被内部>自然植被与防护林之间>防护林外部;对于紧密结构林带,当风速较小时,风速的减弱程度为自然植被与防护林之间>自然植被内部>防护林外部。②防护林带的冠层体积(V)、单位长度林带段胸高断面积(S)、株行距(Q)与自然植被的平均高度(H)、覆盖度(C)协同后和两高度处的相对风速存在极显著相关关系,据此以编程运算得到最小相对风速下二者协同配置的优化模式,即在0.5 m高度处,当V=62.1476 m3、S=0.5756 m2/50m、Q=5.5645 m2、H=1.6889 m、C=0.2878时,二者的协同防风效能达到85.07%;在1.5 m高度处,当V=62.1476 m3、S=0.5237 m2/50m、Q=5.5645 m2、H=1.8154 m、C=0.3073时,二者的协同防风效能达到74.67%。对不同相对风速下二者协同配置的优化模式进行了预测。 相似文献