Characterization of land cover types in Xilin River Basin using multi-temporal Landsat images     

CHEN Siqing  LIU Jiyuan  ZHUANG Dafang  XIAO Xiangming 《地理学报》2003,13(2):131-138

This study conducted computer-aided image analysis of land use and land cover in Xilin River Basin, Inner Mongolia, using 4 sets of Landsat TM/ETM+ images acquired on July 31, 1987, August 11, 1991, September 27, 1997 and May 23, 2000, respectively. Primarily, 17 sub-class land cover types were recognized, including nine grassland types at community level: F. sibiricum steppe, S. baicalensis steppe, A. chinensis + forbs steppe, A. chinensis + bunchgrass steppe, A. chinensis + Ar. frigida steppe, S. grandis + A. chinensis steppe, S. grandis + bunchgrass steppe, S. krylavii steppe, Ar. frigida steppe and eight non-grassland types: active cropland, harvested cropland, urban area, wetland, desertified land, saline and alkaline land, cloud, water body + cloud shadow. To eliminate the classification error existing among different sub-types of the same gross type, the 17 sub-class land cover types were grouped into five gross types: meadow grassland, temperate grassland, desert grassland, cropland and non-grassland. The overall classification accuracy of the five land cover types was 81.0% for 1987, 81.7% for 1991, 80.1% for 1997 and 78.2% for 2000.  相似文献   

黄土高原草本植被水土保持作用研究进展     

李勉  姚文艺  李占斌 《地球科学进展》2005,20(1):74-080

草本植被具有积极的保持水土的作用，在黄土高原生态环境建设中具有不可替代的作用。在系统分析黄土高原草本植被保土减蚀作用研究的过去与现状的基础上，归纳并总结了草被覆盖度与水土流失量、草被植物与地表径流系数、草被植物地下根系与土壤抗冲性及抗蚀性等方面的最新研究进展，并针对各方面存在的问题以及今后有待深入研究的问题进行了探讨。  相似文献   

Soil heterogeneity and the distribution of desert and steppe plant species across a desert-grassland ecotone   总被引：1，自引：0，他引：1  

C.A.Z. Buxbaum  K. Vanderbilt   《Journal of Arid Environments》2007,69(4):617-632

Bouteloua gracilis (Kunth) Lag. ex Griffiths (blue grama), Bouteloua eriopoda (Torr.) Torr. (black grama), and Larrea tridentata Coville (creosotebush) are dominant plants on the McKenzie Flats portion of the Llano de Manzano landform within Sevilleta National Wildlife Refuge in central New Mexico, part of the biome ecotone from the Colorado Shortgrass Steppe to the Chihuahuan Desert. In this study, we examine the hypothesis that soil heterogeneity, determined by variation in surface soil depth, carbonate accumulation, and fine-textured fraction, controls relative dominance of the three species. The area is flat, generally <1% slope; however, abrupt soil differences exist even within the flattest parts of the landscape that correspond to the pattern of buried channels incised in a petrocalcic horizon (caliche) formed in a 0.5–1.2 million year-old paleosol beneath the current surface soil. Multivariate analyses of soil-moisture-related variables suggest that B. gracilis, a Colorado Shortgrass Steppe indicator, dominates the buried paleochannels where Holocene surface deposits are deepest and the argillic (clay-rich) B-horizon is thickest. B. eriopoda, dominant in Chihuahuan Desert grasslands, is most abundant where the buried petrocalcic horizon lies within 40–60 cm of the surface and the argillic horizon is thinner and weakly developed. L. tridentata, an indicator of desertified Chihuahuan Desert shrubland, is dominant where the petrocalcic horizon is exposed or near the surface. This study illustrates the strong relationship between geomorphology, soil development and vegetation patterns in arid and semi-arid environments.  相似文献   

Analysis of runoff generation and soil erosion processes by using environmental radionuclides in semiarid areas of Mongolia   总被引：1，自引：0，他引：1  

Yuichi Onda  Hiroaki Kato  Maki Tsujimura  Dambaravjaa Oyunbaatar 《Journal of Hydrology》2007,333(1):124-132

  相似文献   

内蒙古锡林郭勒盟东部梅勒图组火山岩锆石U-Pb年龄、地球化学特征及其地质意义     

薛晓刚 《地质与勘探》2018,54(5):957-967

内蒙古锡林郭勒盟东部扎布其尔沃布勒吉地区梅勒图组火山岩岩性主要为玄武安山岩、橄榄玄武岩、杏仁-气孔状玄武安山岩夹薄层凝灰岩。LA--ICP--MS锆石U—Pb测年数据显示,火山岩形成于137Ma-138Ma,为早白垩世中期。岩石地球化学数据分析表明：该组火山岩富钠,贫钾（Na2O/K2O比值为1.24~1.54）,里特曼指数σ为2.18~3.57,属正常类型钙碱性系列岩石; 稀土元素富集（∑REE=327.40~534.77×10-6）,LREE/HREE=10.37~17.42,轻、重稀土分馏明显（LaN/YbN=13.08~25.43）;富集大离子亲石元素,高场强元素Ti、Nb、Hf亏损。MgO-FeO*-AL2O3和Th-Hf/3-Ta图解为造山带板内环境碱性玄武岩。其岩浆来源为富集地幔,形成于引张构造背景下。  相似文献   

Using information layers for mapping grassland habitat distribution at local to regional scales     

《International Journal of Applied Earth Observation and Geoinformation》2015

The Natura 2000 network of protected sites is one of the means to enable biodiversity conservation in Europe. EU member states have to undertake surveillance of habitats and species of community interest protected under the Habitat Directive. Remote sensing techniques have been applied successfully to monitor biodiversity aspects according to Natura 2000, but many challenges remain in assessing dynamics and habitat changes outside protected sites. Grasslands are among the most threatened habitats in Europe. In this paper we tested the integration of expert knowledge into different standard classification approaches to map grassland habitats in Schleswig Holstein, Germany. Knowledge about habitat features is represented as raster information layers, and used in subsequent grassland classifications. Overall classification accuracies were highest for the maximum likelihood and support vector machine approaches using RapidEye time series, but results improved for specific grassland classes when information layers were included in the classification process.  相似文献   

Eco-environmental degradation in the northeastern margin of the Qinghai–Tibetan Plateau and comprehensive ecological protection planning     

Hui Wang  Xiaolei Zhou  Changgui Wan  Hua Fu  Feng Zhang  Jizhou Ren 《Environmental Geology》2008,55(5):1135-1147

The regional hydrology and ecosystems of the northeastern margin of the Qinghai–Tibetan Plateau have changed over the past 40 years driven by intense human activity and regional climate changes. Annual mean air temperature has increased in the region. Streamflow from the northeastern margin of the Qinghai–Tibetan Plateau has decreased significantly. Overall, a number of Alpine step meadows and Alpine frigid meadows have seriously degraded. Degeneration of vegetation and grassland led to desertification and frequently induced dust storms. With the continuous increase in cultivated land area, grassland area in the region has dropped significantly since the 1960s. At present, degraded grassland occupies about 83% of total usable grassland area. As the number of livestock increased, range condition deteriorated and the carrying capacity was reduced. The forest area in the northeastern margin of the Qinghai–Tibetan Plateau has decreased by 20%, and the local ecosystem has become very fragile. Given the relatively stable weather conditions, the northeastern margin of the Qinghai–Tibetan Plateau can be characterized by its three major ecosystems: grassland ecosystem, forest ecosystem and wetland ecosystem, which are crucial in maintaining the ecological stability. Changes in these ecosystems could influence sustainable development in the region. To avoid further deterioration of the environment and ecosystems, it is important to establish and implement ecosystem protection planning. Some effective measures are essential in this respect, including technical and political considerations.  相似文献   

Modeling gross primary production of a temperate grassland ecosystem in Inner Mongolia,China, using MODIS imagery and climate data   总被引：5，自引：0，他引：5  

WeiXing Wu  ShaoQiang Wang  XiangMing Xiao  GuiRui Yu  YuLing Fu  YanBin Hao 《中国科学D辑(英文版)》2008,51(10):1501-1512

Carbon fluxes in temperate grassland ecosystems are characterized by large inter-annual variations due to fluctuations in precipitation and land water availability. Since an eddy flux tower has been in operation in the Xilin Gol grassland, which belongs to typical temperate grassland in North China, in this study, observed eddy covariance flux data were used to critically evaluate the biophysical per- formance of different remote sensing vegetation indices in relation to carbon fluxes. Furthermore, vegetation photosynthesis model (VPM) was introduced to estimate gross primary production (GPP) of the grassland ecosystem for assessing its dependability. As defined by the input variables of VPM, Moderate Resolution Imaging Spectroradimeter (MODIS) and standard data product MOD09A1 were downloaded for calculating enhanced vegetation index (EVI) and land surface water index (LSWI). Measured air temperature (Ta) and photosynthetically active radiation (PAR) data were also included for model simulating. Field CO2 flux data, during the period from May, 2003 to September, 2005, were used to estimate the "observed" GPP (GPPobs) for validation. The seasonal dynamics of GPP predicted from VPM (GPPVPM) was compared quite well (R2=0.903, N=111, p<0.0001) with the observed GPP. The ag- gregate GPPVPM for the study period was 641.5 g C·m?2, representing a ~6% over-estimation, compared with GPPobs. Additionally, GPP predicted from other two typical production efficiency model (PEM) represents either higher overestimation or lower underestimation to GPPobs. Results of this study demonstrate that VPM has potential for estimating site-level or regional grassland GPP, and might be an effective tool for scaling-up carbon fluxes.  相似文献   

A numerical experiment study for effects of the grassland desertification on summer drought in North China   总被引：2，自引：2，他引：0  

Zheng Weizhong  Ni Yunqi 《大气科学进展》1999,16(2):251-262

1IntroductionDManyobservationsandstudiesindicatethatthesummerrainfallinNorthChinadecreasessignificantlyduringrecenttwentyyears.Theobviousreductiontendencycanbeseenfromthevariationofpercentageofsummerrainfallanomaly(June--August)intheplainofNorthChina...  相似文献   

基于ArcMap的全国草地资源图的研制   总被引：1，自引：0，他引：1  

侯西勇 《地球信息科学学报》2003,5(4):104-109

详细地介绍了利用美国 ESRI公司的 Arc GIS 8.1软件产品中的 Arc Map模块完成全国草地资源专题地图的计算机辅助设计和样品图打印输出工作的全部过程以及需要注意的问题。草地资源数据来自对 1 999～ 2 0 0 0年全国范围 L andsat TM遥感影像的计算机解译结果 ,背景数据为 1∶ 5 0 0 0 0 0的地理底图数据 ,包括居民点、行政边界、公路、铁路和水系等要素 ;所有数据都已经存贮为 ARC/ INFO- Coverage文件格式。该工作有两部分具体的任务 :1分省草地资源制图设计与样品图输出 ;2 1∶ 5 0 0 0 0 0分幅草地资源制图设计与样品图输出。两部分共完成和输出 2 4 0余幅草地资源专题地图。  相似文献