基于MODIS数据的柴达木盆地南缘绿洲土地覆盖动态变化研究

基于遥感和GIS技术手段,利用2000—2009年生长季的MODIS数据对柴达木盆地南缘绿洲进行了土地覆盖分类,得到前期（2000—2004年）和后期（2005—2009年）两期土地分类图以及2000—2009年土地覆盖类型变化趋势图,分析了2000—2009年10 a尺度上该地区土地覆盖类型的面积变化以及空间分布格局。分析得知,柴达木盆地南缘绿洲同时存在两种演化趋势:绿洲化和荒漠化。近10 a来绿洲化的总面积为1 040 km2,占研究区面积的4.58%,主要集中在荒漠化区域与稳定区域之间;荒漠化的总面积为399 km2,占研究区面积的1.76%,其中80%集中在绿洲边缘（4 km以内）,也就是说,绿洲的边缘地区相对于绿洲的其他区域更易于发生荒漠化现象。从整个研究区来看,绿洲化趋势高于荒漠化趋势,其原因可能主要是由于近年来气候变暖,昆仑山上大量冰雪融化,为下游绿洲提供了一定的水资源,但绿洲上游一些地区人类活动的加剧使用了大量的水资源间接地影响了绿洲的演化,使得绿洲边缘水资源缺乏的地区荒漠化加剧。     

2000~2014年黑龙江流域（中国）植被覆盖时空变化及其对气候变化的响应

采用MODIS/NDVI数据,利用Theil-Sen Median 趋势分析、Mann-Kendall 以及Hurst指数方法分析2000~2014年黑龙江流域（中国）植被的时空变化特征、植被变化发展趋势及可持续性特征;应用相关分析法研究了气候变化对植被生长的影响。结果表明,2000~2014年黑龙江流域（中国）植被NDVI指数呈缓慢增加趋势,山区植被覆盖增加显著,东北部平原区植被覆盖持续退化,总体上植被覆盖持续改善能力较弱。植被NDVI对气候响应的季节差异显著,且不同类型植被对气候因子的响应不一致：春季植被NDVI主要受温度影响,夏季植被NDVI主要受降水量影响,秋季林地NDVI与温度正相关、草地NDVI与降雨量正相关。     

抚仙湖流域植被覆盖度时空分异及其与坡度的关系

采用像元二分模型,以1974-2014年间的10期Landsat 5/8影像和DEM数据,对抚仙湖流域植被覆盖动态变化进行监测,并结合基础地理信息数据、行政区划界资料、行业部门专题资料等,分析流域植被覆盖时空分异及其与坡度的关系.结果表明:(1)1974-2014年,抚仙湖流域裸地(Ⅰ级)面积波动极小,低植被覆盖(Ⅱ级)、中低植被覆盖(Ⅲ级)、中高植被覆盖(Ⅳ级)面积变化波动大,变化趋势线数次出现谷值和峰值,高植被覆盖(Ⅴ级)面积则呈增加趋势.(2)坡度较小、地势较平缓的区域(0°~15°)以裸地和低植被覆盖为主;中低植被覆盖度、中高植被覆盖和高植被覆盖度主要分布在地势比较陡峭的区域(>15°).(3)抚仙湖流域各年份植被覆盖度Ⅰ级面积最大,1974,1977,1989,1996年Ⅱ,Ⅲ级面积较大,而Ⅳ,Ⅴ级面积较小;2000年后的Ⅱ,Ⅲ,Ⅳ级面积变化较小;2006,2009,2012,2014年Ⅳ,Ⅴ级的面积较大,Ⅱ,Ⅲ级的面积较小.     

Spatially-explicit sensitivity analysis of an agent-based model of land use change

The complexity of land use and land cover (LULC) change models is often attributed to spatial heterogeneity of the phenomena they try to emulate. The associated outcome uncertainty stems from a combination of model unknowns. Contrarily to the widely shared consensus on the importance of evaluating outcome uncertainty, little attention has been given to the role a well-structured spatially explicit sensitivity analysis (SSA) of LULC models can play in corroborating model results. In this article, I propose a methodology for SSA that employs sensitivity indices (SIs), which decompose outcome uncertainty and allocate it to various combinations of inputs. Using an agent-based model of residential development, I explore the utility of the methodology in explaining the uncertainty of simulated land use change. Model sensitivity is analyzed using two approaches. The first is spatially inexplicit in that it applies SI to scalar outputs, where outcome land use maps are lumped into spatial statistics. The second approach, which is spatially explicit, employs the maps directly in SI calculations. It generates sensitivity maps that allow for identifying regions of factor influence, that is, areas where a particular input contributes most to the clusters of residential development uncertainty. I demonstrate that these two approaches are complementary, but at the same time can lead to different decisions regarding input factor prioritization.     

Graph-assisted landscape monitoring

The structure of computational spatial analysis has mostly built on data lattices inherited from cartography, where visualization of information takes priority over analysis. In these framings, spatial relationships cannot easily be encoded into traditional data lattices. This hinders spatial analysis that emphasizes how interactions among spatial entities reflect mutual inter-relationships. This paper explores how graph theoretic principles can support spatiotemporal analysis by enabling assessment of spatial and temporal relationships in landscape monitoring.     

土地利用结构及其驱动因子的统计分析——以榆林地区为例

本文采用了典型相关分析这一经典的数理统计方法，对榆林地区土地利用结构的驱动因子进行了统计分析。通过大型社会科学统计软件包SPSS操作运行，并对统计结果进行专业分析，定量诊断出各驱动因子对该区土地利用结构分布贡献作用的大小。同时运用典型相关系数和冗余度分析，对诊断结果进行了检验。     

Relative importance of climate,topography, and habitats for breeding wetland birds with different latitudinal distributions in the Czech Republic

Given species' vulnerability to climate change, land use change, and habitat loss, it is pertinent to examine how the distribution of a particular species is related to those factors. We assessed the use of climate, habitat, and topography data for modeling the distributions of 14 central European wetland birds, and compared the relative importance of these factors among bird groups with differing latitudinal distributions in Europe. We used the Third Atlas of Breeding Birds in the Czech Republic as a source of species distribution data. Variables were derived from Corine Land Cover, WorldClim, and Shuttle Radar Topography Mission (SRTM) data. Hierarchical partitioning and multiple logistic models identified climatic, topographical, and habitat predictors as important determinants of distribution for each of the species under study. However, the relative contributions of particular variables differed among the species. Climatic, topographical, and habitat factor groups also differed in their importance to latitudinal species groups. Our results indicated that wetland birds with range margins close to the Czech Republic were potentially limited by two different factors: climate conditions impact the southerly distributed species and the availability of suitable habitat affects the northerly distributed species. The accuracy of the study models varied from fair to high (the area under curve values was 0.60–0.89) and revealed negative correlations with the relative occurrence area. In this study, we propose that any difference in model performance is more attributable to data characteristics than to a species' geographical characteristics.     

Improving the factual knowledge of landscapes: Following up the European Landscape Convention with a comparative historical analysis of forces of landscape change in the Sjodalen and St⊘lsheimen mountain areas,Norway

A focus of implementing the European Landscape Convention (ELC) in Norway is on improving the factual knowledge of landscapes, which implies analysing the forces transforming them. The article aims to identify important forces of change and to elucidate its complexity by a comparative historical study of land cover and land use in two mountain areas in Western and Eastern Norway. The land covers and uses in focus are transport infrastructure, seasonal farming, vegetation, tourism and outdoor recreation, and nature and landscape protection. Based on an understanding of forces as something being exerted, a framework including pressure, attraction, friction, repulsion, and working force is developed. A comprehensive literature analysis shows how differences in intensity and extent of land use and development of land cover result from a complex interaction of common extrinsic forces with locally different intrinsic forces. To control landscape change and to maintain diversity among landscapes as a Europe-wide resource, the national implementation of the ELC will require a strong focus on the local level. Moreover, understanding the ELC as an origin of forces is recommended, because it allows more appropriate individual responses to landscape change.     

Responses of rural households to the impacts of population and land-use changes along the Eastern Escarpment of Wello,Ethiopia

The article analyses the effects of changes in land cover and land use changes together with population changes on the livelihood of rural households, and also farming households' responses to these changes, in typical rural settings of north-eastern Ethiopia. The study shows that the immediate impact of shrubland and forest increase since the late 1970s, coupled with population increase, is an exponential fall of per capita cropland and grazing land, which are the principal physical assets of livelihoods of the rural farming community in the area. Furthermore, the study reveals that the scarcity of cultivated land in the area neither brings about agricultural intensification nor leads to diversification into non-farm activities, and farmers did not respond to the scarcity of cultivated land through large out-migration. In general, the Boserupian assumption of land-use intensification through improved labour and land productivity did not happen in the region. Rather, the Malthusian thesis seems appropriate. The majority of farming households are destitute, unable to satisfy their own food demands, and live in absolute poverty. This situation has been brought about not only due to population pressure but also as a result of the policies that have been applied in all systems since the 1950s.