应用遥感技术研究土地利用/土地覆盖变化及其对土壤侵蚀过程的影响--以印度北部Pali Gad山地流域为例

应用遥感技术评估了印度北部Pali Gad山地流域过去几十年里土地利用／土地覆盖变化及其造成的土壤侵蚀程度,并基于摩根参数模型（Morgan Parametric Model）的方法来测定土壤的侵蚀程度;结果表明,由于不同的坡向受到太阳光照的不同可以引起土地覆盖的变迁;海拔和坡度已不再是阻碍人们获取自然资源的因素,人们的活动范围正转移到更高的海拔和更陡峭的坡度;揭示了土地利用／土地覆盖变化对土壤侵蚀进程有着直接的影响。     

1995～2000年中国沙地空间格局变化的遥感研究

利用遥感方法 ,在覆盖全国的 Landsat-TM数据的基础上 ,对 1 995年和 2 0 0 0年中国沙地的空间分布格局与动态变化进行了调查。结果显示了 2 0 0 0年中国沙地总面积为 5 9× 1 0 4 km2 ,主要分布于各主要沙漠和我国的 7个主要省份。1 995～ 2 0 0 0年 ,有 470 9.7km2的土地转化为沙地 ,同时又有 2 1 5 6.4km2的沙地转化为其它土地利用类型 ,沙地总面积扩大了2 5 5 3 .3 km2 。对变化为沙地的土地进行分析 ,发现草地占主要部分 ,但耕地所占的比重也非常突出 ,同时也表明有部分沙地变化为草地和耕地。根据土地沙化的空间分布特征 ,将土地沙化过程分为 5种格局 :沙地 -绿洲型、沙漠型、沙地 -黄土过渡型、沙地 -草地型和高原风蚀型。通过对中国发生土地风蚀沙化的主要省份在 1 995～ 2 0 0 0年间的土地利用动态变化发现 ,土地利用变化是促使土地发生沙化的一个重要因素。在 5 a的时间里 ,7个省份耕地总面积扩大了 90 3 9.7km2 ,草地减少了 1 1 5 97.9km2。耕地的增加部分几乎均表现为对草地的侵占 ,土地变为沙地也主要发生在草地区。人为因素导致的耕地面积扩大是促使土地沙化的重要原因。对主要省份的土地利用方式进行分析 ,探讨不同地区减轻土地沙化趋势下的土地利用布局。     

Land cover associated with hantavirus presence in Paraguay

Aims  Hantaviruses are zoonotic, aetiological agents maintained by rodents of the family Muridae. The occurrence of hantavirus in rodent hosts has been correlated to a number of climatic and environmental factors, including landscape structure. To date, most of these correlative studies have been conducted at moderate to fine spatial resolution. Our aim is to determine whether land cover classes defined at a mapping resolution of 1 km² are associated with rodents with antibodies to hantavirus in Paraguay.
Location  The Republic of Paraguay.
Methods  A total of 362 rodents from 10 species known to host hantaviruses were tested for the presence of hantavirus antibodies, resulting in 27 seropositive individuals. This data base was then combined with a map of six land cover types derived from coarse resolution remote sensing data to create a series of contingency tables, which were used to relate serostatus to land cover type using nonparametric tests of proportions and qualitative comparison of observed and expected values.
Results  There was a significant difference in habitat association between seropositive and seronegative rodents when species were pooled. Seropositive rodents were found with disproportionately high frequency in areas where human disturbance in the form of intensive and mosaic agricultural landscapes was present.
Main conclusions  Human-disturbed land cover classes have a detectable relationship to the hantavirus serostatus of host population rodents when observed at coarse spatial resolutions. Although coarse-grained analysis does not lead to any conclusions as to why agricultural land cover is more likely to harbour seropositive rodents, the relationship between them could form the basis for a monitoring system designed to relate land cover change to potential viral outbreaks in rodents and humans.     

陕北榆林地区土地沙漠化动态遥感研究

土地沙漠化是人类面临的一个重要环境问题,在人为过度的经济活动干拢和生态脆弱的自然环境变化的影响下,正在继续蔓延,日益扩大,已引起国际社会和有识之士的高度重视。掌握其动态变化的规律,监测其发展趋势乃成为当前国际沙漠化研究的一个重要内容。地处陕西北部长城沿线的榆林地区,生态上较脆弱,气候上较敏感。笔者利用1984年和1994年两期ＴＭ图像进行判读勾绘,编制土地沙漠化类型图,在ＧＩＳ的支持下,建立空间数据库,套合叠加产生一种新的图件土地沙漠化动态图,获取动态变化资料数据,掌握了该区十年来土地沙漠化的动态变化趋势。1　区域环…     

内蒙古锡林郭勒盟草原产草量动态遥感估算

草原产草量的监测是草地资源空间动态研究的重要衡量指标,是草地资源合理利用和载畜平衡监测的重要依据.基于371个样地调查数据和2005～2009年的MODIS-NDVI遥感数据,建立地面样方的产草量与遥感数据的关系模型,模拟分析了内蒙古锡林郭勒盟草原产草量的时空分布.结果表明：（1）建立的各模型方程均有较好的相关关系,其中幂函数的相关关系最优,通过预留样方数据的验证,模型精度为78%,幂函数模型作为遥感估测应用可行;（2）锡林郭勒盟草原的产草量5年平均为3455万吨,折合干草总量为1112万吨,平均单产为567.23kg/hm2,草原产草量的空间分布呈东高西低的格局;（3）2005～2009年,锡林郭勒盟草原产草量有明显的波动,干草变化范围为800～1400万吨,变异系数为20.42%;（4）不同草地类型的产草量及其年际间变化存在较大的差异,荒漠类草原产草量低,年际间变化较大;草甸类草原产草量高,年际间变化相对较小.草原产草量的时空变化还与降水量、气温等主要气候因素关系密切,特别是受降水量的时空变化影响显著.研究结果可以为中国草地资源的保护及合理利用提供参考依据.     

Multiple Methods in the Study of Driving Forces of Land Use and Land Cover Change: A Case Study of SE Kajiado District,Kenya

This landscape-scale study combines analysis of multitemporal satellite imagery spanning 30 years and information from field studies extending over 25 years to assess the extent and causes of land use and land cover change in the Loitokitok area, southeast Kajiado District, Kenya. Rain fed and irrigated agriculture, livestock herding, and wildlife and tourism have all experienced rapid change in their structure, extent, and interactions over the past 30 years in response to a variety of economic, cultural, political, institutional, and demographic processes. Land use patterns and processes are explored through a complementary application of interpretation of satellite imagery and case study analysis that explicitly addresses the local–national spatial scale over a time frame appropriate to the identification of fundamental causal processes. The results illustrate that this combination provides an effective basis for describing and explaining patterns of land use and land cover change and their root causes.     

Regression Techniques for Examining Land Use/Cover Change: A Case Study of a Mediterranean Landscape

In many areas of the northern Mediterranean Basin the abundance of forest and scrubland vegetation is increasing, commensurate with decreases in agricultural land use(s). Much of the land use/cover change (LUCC) in this region is associated with the marginalization of traditional agricultural practices due to ongoing socioeconomic shifts and subsequent ecological change. Regression-based models of LUCC have two purposes: (i) to aid explanation of the processes driving change and/or (ii) spatial projection of the changes themselves. The independent variables contained in the single ‘best’ regression model (that is, that which minimizes variation in the dependent variable) cannot be inferred as providing the strongest causal relationship with the dependent variable. Here, we examine the utility of hierarchical partitioning and multinomial regression models for, respectively, explanation and prediction of LUCC in EU Special Protection Area 56, ‘Encinares del río Alberche y Cofio’ (SPA 56) near Madrid, Spain. Hierarchical partitioning estimates the contribution of regression model variables, both independently and in conjunction with other variables in a model, to the total variance explained by that model and is a tool to isolate important causal variables. By using hierarchical partitioning we find that the combined effects of factors driving land cover transitions varies with land cover classification, with a coarser classification reducing explained variance in LUCC. We use multinomial logistic regression models solely for projecting change, finding that accuracies of maps produced vary by land cover classification and are influenced by differing spatial resolutions of socioeconomic and biophysical data. When examining LUCC in human-dominated landscapes such as those of the Mediterranean Basin, the availability and analysis of spatial data at scales that match causal processes is vital to the performance of the statistical modelling techniques used here.     

Temporal Heterogeneity in the Study of African Land Use

This paper introduces a set of four collaborative papers exploring temporal heterogeneity in the analysis of African land use over a decadal time period, from 10 to 50 years, in the second half of the twentieth century. The four cases were chosen amongst the seven teams of anthropologists, human geographers and remote sensing specialists who had carried out long-term research and who met to discuss their findings at a workshop in 2003. All seven teams’ work and the collective discussion—on Casamance (Senegal), Brong Ahafo (Ghana), Southern Niger/Northern Cote d’Ivoire, Oyo State (Nigeria), Maasai Mara (Kenya and Tanzania), Gwembe (Zambia), and Malawi—inform this introduction. We identify several temporal processes in all the cases, each operating on its own temporal frame: population growth and, above all, mobility; livelihood change through crop and occupational change; tenure ambiguity; powerful though “punctuated” interventions by state policy; and climate change. Conceptual and methodological implications are disussed.

Fire, People and Pixels: Linking Social Science and Remote Sensing to Understand Underlying Causes and Impacts of Fires in Indonesia

This study in the wake of 1990s fire catastrophes identifies and analyzes underlying causes of vegetation fires in eight locations across Borneo and Sumatra. Multidisciplinary and multiscale analysis integrates geospatial technologies with varied social research approaches and participatory mapping. It helps fill a void of site-specific evidence on diverse underlying causes of the Indonesian fires, despite emerging consensus on macrolevel causes and impacts, and policy debates on preventing future fire disasters. Our most important findings include confirmation of multiple direct and underlying fire causes at each of the eight locations, no single dominant fire cause at any site, and wide differences in fire causes among sites. Conclusions emphasize the importance of location specific studies within a regional analytical context. Our “hybrid” research methods demonstrate the explanatory power of integrating geospatial and social analysis techniques, and the benefits of analyzing fire causes and impacts at multiple scales in varied locations across diverse regions.     

Stories Remote Sensing Images Can Tell: Integrating Remote Sensing Analysis with Ethnographic Research in the Study of Cultural Landscapes

Although remote sensing techniques have become important methodologies in geographical studies, their quantitative tradition and empirical strength have discouraged their use in ethnographically based research of cultural landscapes. Using Uxin Ju of Inner Mongolia in China as a case study, this paper, adopting the approach of mixed methods, explores the integration of remote sensing techniques with ethnographic research in the study of cultural landscapes. In particular, it examines how remote sensing techniques, combined with ethnographic methods, can contribute to the study of cultural change and human perceptions as they relate to the landscape. Remote sensing analysis offers additional stories about changes in the landscape–stories not told by interviewees, or stories that supplement the account of interviewees. These stories provide important insights into cultural change and culture–landscape relationships. Through this case study, I argue that remote sensing techniques can greatly enhance ethnographic research in the study of cultural landscapes.     

An Untidy Cover: Invasion of Bracken Fern in the Shifting Cultivation Systems of Southern Yucatán, Mexico

In land change science studies, a cover type is defined by land surface attributes, specifically including the types of vegetation, topography and human structures, which makes it difficult to characterize land cover as discrete classes. One of the challenges in characterizing a land-cover type is to distinguish variability within the class from actual land-cover transformation. The spread of plant invasions in tropical systems is affected by seasonal variations and disturbances such as agricultural activities and fires, making it difficult to determine the spread through thematic classifications. In this paper, we estimate the changes in spatial extent and seasonal variation of bracken fern invasion in Southern Yucatán from 1989 to 2005 by using a linear mixture model (LMM), a widely used method in the classification of remotely sensed data. The results show an increase in areas affected by bracken from 40 km² in 1989 to almost 80 km² in 2000. Lower estimates of the invasion resulted from data acquired at the end of the dry season (March–May), when bracken mixes with secondary vegetation or is removed by fires. The accuracy of the maps is estimated through the use of sketch maps of farmer's parcels and field data collected from 2000 to 2001. Understanding the spatial distribution and annual variability of bracken fern cover in the region is critical to determining the relation between disturbances such as fire and forest recovery. Using LMM may enhance this understanding by giving a more accurate picture of the extent and distribution of bracken fern invasion.
Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp     

云南澜沧江流域土地利用和覆盖变化

由人类活动引起的土地利用和地被覆盖的变化是地球上环境变化的主要原因。上世纪90年代是云南省经济发展和环境变化的活跃时期。本文通过现代卫星遥感技术、地理信息系统和其它多学科手段相结合 ,系统调查评估了云南澜沧江流域 1990年至 1998年间土地利用和地被覆盖的变化 ,结果显示流域中林业用地面积从 1990年的 6 4 9%增长到 1998年的6 6 4 % ,但是森林有林地 (郁闭度 >30 %的天然林和人工林 )从 1990年的 5 2 6 %减少到 1998年的 35 3%。并且分析大规模商业性森林砍伐、基础建设、经济作物的种植、刀耕火种、薪材过度采集和砍伐建筑用材等引起了森林的结构的显著变化和退化 ,从而导致了生物多样性的下降。     

Land cover dynamics of different topographic conditions in Beijing, China

Topographic conditions play an important role in controlling land cover dynamic processes. In this study, remotely sensed data and the geographic information system were applied to analyze the changes in land cover along topographic gradients from 1978 to 2001 in Beijing, a rapidly urbanized mega city in China. The study was based on five periods of land cover maps derived from remotely sensed data: Landsat MSS for 1978, Landsat TM for 1984, 1992, 1996 and 2001, and the digital elevation model (DEM) derived from 1:250,000 topographic map. The whole area was divided into ten land cover types: conifer forest, broadleaf forest, mixed forest, shrub, brushwood, meadow, farmland, built-up, water body and bare land. The results are summarized as follows. (1) Shrub, forest, farmland and builtup consist of the main land cover types of the Beijing area. The most significant land cover change from 1978 to 2001 was the decrease of the farmland and expansion of the builtup area. Farmland decreased from 6354 to 3813 km2 in the 23 years, while the built-up area increased from 421 to 2642 km2. Meanwhile, the coverage of forest increased from 17.2% to 24.7% of the total area. The conversion matrix analysis indicated that the transformation of farmland to the built-up area was the most significant process and afforestation was the primary cause of the replacement of shrub to forest. (2) Topographic conditions are of great importance to the distribution of land cover types and the process of land cover changes. Elevation has an intensive impact on the distribution of land cover types. The area below 100 m mostly consists of farmland and built-up areas, while the area above 100 m is mainly covered by shrub and forest. Shrub has the maximum frequency in areas between 100 and 1000 m, while forest has dominance in areas above 800 m. According to the analysis of land cover changes in different ranges of elevation, the greatest change below 100 m was the process of urbanization. The process of the main land cover change occurred above 100 m was the transformation from shrub to forest. This result was consistent with the vertical change of natural vegetation distribution in Beijing. (3) Slope has a great influence on the distribution of land cover. Farmland and built-up areas are mostly distributed in flat areas, while shrub and forest occupy steeper areas compared with other land cover types. Forest frequency increased with the increasing slope. Land cover changes differed from the slope gradients. In the plain area, the land cover change occurred as the result of urbanization. With the increasing of the slope gradient, afforestation, which converts shrub to forest, was the process of the primary land cover change. __________ Translated from Journal of Plant Ecology, 2006, 30(2): 239–251 [译自: 植物生态学报]     

Land cover dynamics of different topographic conditions in Beijing,China

Topographic conditions play an important role in controlling land cover dynamic processes.In this study,remotely sensed data and the geographic information system were applied to analyze the changes in land cover along topographic gradients from 1978 to 2001 in Beijing,a rapidly urbanized mega city in China.The study was based on five periods of land cover maps derived from remotely sensed data:Landsat MSS for 1978,Landsat TM for 1984,"1992,1996 and 2001,and the digital elevation model (DEM) derived from 1:250,000 topographic map.The whole area was divided into ten land cover types:conifer forest,broadleaf forest,mixed forest,shrub,brushwood,meadow,farmland,built-up,water body and bare land.The results are summarized as follows.(1) Shrub,forest,farmland and builtup consist of the main land cover types of the Beijing area.The most significant land cover change from 1978 to 2001 was the decrease of the farmland and expansion of the builtup area.Farmland decreased from 6354 to 3813 km2 in the 23 years,while the built-up area increased from 421 to 2642 km2.Meanwhile,the coverage of forest increased from 17.2% to 24.7% of the total area.The conversion matrix analysis indicated that the transformation of farmland to the built-up area was the most significant process and afforestation was the primary cause of the replacement of shrub to forest.(2) Topographic conditions are of great importance to the distribution of land cover types and the process of land cover changes.Elevation has an intensive impact on the distribution of land cover types.The area below 100 m mostly consists of farmland and built-up areas,while the area above 100 m is mainly covered by shrub and forest.Shrub has the maximum frequency in areas between 100 and 1000 m,while forest has dominance in areas above 800 m.According to the analysis of land cover changes in different ranges of elevation,the greatest change below 100 m was the process of urbanization.The process of the main land cover change occurred above 100 m was the transformation from shrub to forest.This result was consistent with the vertical change of natural vegetation distribution in Beijing.(3) Slope has a great influence on the distribution of land cover.Farmland and built-up areas are mostly distributed in fiat areas,while shrub and forest occupy steeper areas compared with other land cover types.Forest frequency increased with the increasing slope.Land cover changes differed from the slope gradients.In the plain area,the land cover change occurred as the result of urbanization.With the increasing of the slope gradient,afforestation,which converts shrub to forest,was the process of the primary land cover change.     

Patterns of Land Cover Change in and Around Madidi National Park, Bolivia

This study examines how human land uses and biophysical factors serve as predictors of land cover change in and around Madidi National Park in Bolivia. The Greater Madidi Landscape ranges over an elevational gradient from < 200 m in the Amazon basin to 6000 m in the high Andes, contains more than ten major ecosystem types, and several protected areas and sustainable use zones. In this study, Landsat Thematic Mapper satellite images collected over the study area at the beginning of the 1990s and then the 2000s were classified according to broad land cover types. Below elevations of 3000 m, the landscape experienced equal rates of deforestation and secondary forest increases of approximately 0.63 percent annually, resulting in no significant net change. Below elevations of 1000 m, however, we found an annual net loss in forest cover of 0.11 percent. Across the landscape, land cover change was most likely to occur near areas previously deforested, near roads and population centers, and at low elevations. We found net deforestation rates to be inversely related to strength of natural resource protection laws in protected areas and other jurisdictions. Results suggest little net change for the landscape as a whole, but that local scale changes may be significant, particularly near roads. Management policies favorable for biodiversity conservation in this landscape should limit the building of new roads and immigration to biologically sensitive areas and continue to support protected areas, which are achieving a positive result for forest conservation.     

GIS and Remote Sensing for Detecting Yield Loss in Cranberry Culture

The primary goal of our research is to develop key elements of a precision agriculture program applicable to high-value woody perennial crops, such as cranberries. These crop systems exhibit tremendous variability in crop yields and quality as imposed by variations in soil properties (water availability and nutrient deficiency) that lead to crop stress (disease development and weed competition). Some of the variability present in the growing environment results in persistent yield losses as well as crop-quality reductions. We are using state-of-the-art methodologies (GIS, GPS, remote sensing) to identify and map spatial variations of the crop. Through image-processing methods (NDVI and unsupervised classification), approximately 65% of the variation in yield was described using 4-m multispectral satellite data as a base image.     

A new land-cover map of Africa for the year 2000

Aim In the framework of the Global Land Cover 2000 (GLC 2000), a land‐cover map of Africa has been produced at a spatial resolution of 1 km using data from four sensors on‐board four different Earth observing satellites. Location The map documents the location and distribution of major vegetation types and non‐vegetated land surface formations for the entire African continent plus Madagascar and the other surrounding islands. Methods The bulk of these data were acquired on a daily basis throughout the year 2000 by the VEGETATION sensor on‐board the SPOT‐4 satellite. The map of vegetation cover has been produced based upon the spectral response and the temporal profile of the vegetation cover. Digital image processing and geographical information systems techniques were employed, together with local knowledge, high resolution imagery and expert consultation, to compile a cartographic map product. Radar data and thermal sensors were also used for specific land‐cover classes. Results A total of 27 land cover categories are documented, which has more thematic classes than previously published land cover maps of Africa contain. Systematic comparison with existing land cover data and 30‐m resolution imagery from Landsat are presented, and the map is also compared with other pan‐continental land cover maps. The map and digital data base are freely available for non‐commercial uses from http://www.gvm.jrc.it/tem/africa/products.htm Main conclusions The map improves our state of knowledge of the land‐cover of Africa and presents the most spatially detailed view yet published at this scale. This first version of the map should provide an important input for regional stratification and planning purposes for natural resources, biodiversity and climate studies.     

Identifying and quantifying uncertainty and spatial disagreement in the comparison of Global Land Cover for different applications

This paper provides a methodology for comparing global land cover maps that allows for differences in legend definitions between products to be taken into account. The legends of the two maps are first reconciled by creating a legend lookup table that shows how the legends map onto one another. Where there is overlap, the specific definitions for each legend class are used to calculate the degree of overlap between legend classes. In this way, one‐to‐many mappings are accounted for unlike in most methods where the legend definitions are often forced into place. Another advantage over previous map comparison methods is that application‐specific requirements are captured using expert input, whereby the user rates the importance of disagreement between different legend classes based on the needs of the application. This user‐defined matrix in conjunction with the degree of overlap between legend classes is applied on a pixel‐by‐pixel basis to create maps of spatial disagreement and uncertainty. The user can then highlight the areas of highest thematic uncertainty and disagreement between the different land cover maps allowing for areas that require further detailed examination to be readily identified. It would also be possible for several users to input their knowledge into the process, leading to a potentially more robust comparison of land cover products. The methodology of map comparison is illustrated using different land cover products including Global Land Cover 2000 (GLC‐2000) and the MODIS land cover data set. Two diverse applications are provided including the estimation of global forest cover and monitoring of agricultural land. In the case of global forest cover, an example was provided for Columbia, which showed that the MODIS land cover map overestimates forest cover in comparison with the GLC‐2000. The agricultural example, on the other hand, served to illustrate that for Sudan, MODIS tends to underestimate crop areas while GLC‐2000 overestimates them.     

基于遥感和GIS的土地利用分类方法及其在土地退化程度分析中的应用——以陕西横山雷龙湾地区为例

基于陕西省横山县雷龙湾地区的遥感ETM＋影像,分别采用最大似然法和光谱角制图分类（SAM）方法进行了该区的土地利用类型分类。其中,光谱角制图分类利用最小噪声分离（MNF）及像元纯净指数（PPI）方法提取研究区的地类终端端元,在此基础上绘制土地利用类型图。最大似然法对水体及耕地的分类精度较高,而其它地类精度稍差,沙地有较大漏分;而基于像元纯净指数的光谱角制图法分类对沙地、水体分类效果较好,对建筑用地和非建筑用地区分度较高,但林地和草地有一定混分。根据研究区反照率影像、NDVI以及湿度图像构造了一个土地退化程度指数模型,并选择一定的系数对研究区的土地退化程度进行了分类,利用GIS软件成图输出。利用光谱角制图分类的纯净像元样本进行比较分析,发现土地退化程度指数与土地利用的相关性较强,表明该方法可以较好地反映当地的土地退化程度情况。     

利用IKONOS卫星数据和分形方法研究南麂岛土地覆盖状况

研究南麂岛的土地覆盖类型及其空间分布和结构特征。利用具有1米空间分辨率的IKONOS卫星遥感数据,提取南麂岛的植被覆盖和土地利用信息,获得草地、灌木林地、庄稼地和居民地等主要土地覆盖类型及其分布图。然后利用分形几何方法建立南麂岛土地覆盖类型特性分析模型,从斑块的面积效应、覆盖类型的分形分析、单个斑块的分形分析和覆盖类型分形特征差异显著性等方面进行分析讨论。研究结果表明,南麂岛的草地和灌木林地的分形维数较大,而庄稼地和居民地的分形维数较小,说明草地和灌木林地的斑块的结构特征和边界比庄稼地和居民地更为复杂。进一步研究表明,斑块的分形特性与其受人类活动的干扰程度密切相关。