Glacier recession is a globally occurring trend. Although a rich body of work has documented glacial response to climate warming, few studies have assessed vegetation cover change in recently deglaciated areas, especi...Glacier recession is a globally occurring trend. Although a rich body of work has documented glacial response to climate warming, few studies have assessed vegetation cover change in recently deglaciated areas, especially using geospatial technologies. Here, vegetation change at two glacier forefronts in Glacier National Park, Montana, U.S.A.was quantified through remote sensing analysis,fieldwork validation, and statistical modeling.Specifically, we assessed the spatial and temporal patterns of landcover change at the two glacier forefronts in Glacier National Park and determined the role of selected biophysical terrain factors(elevation, slope, aspect, solar radiation, flow accumulation, topographic wetness index, and surficial geology) on vegetation change(from nonvegetated to vegetated cover) at the deglaciated areas.Landsat imagery of the study locations in 1991, 2003,and 2015 were classified and validated using visual interpretation. Model results revealed geographic differences in biophysical correlates of vegetation change between the study areas, suggesting that terrain variation is a key factor affecting spatialtemporal patterns of vegetation change. At Jackson Glacier forefront, increases in vegetation over some portion or all of the study period were negatively associated with elevation, slope angle, and consolidated bedrock. At Grinnell Glacier forefront,increases in vegetation associated negatively with elevation and positively with solar radiation.Integrated geospatial and field approaches to the study of vegetation change in recently deglaciated terrain are recommended to understand and monitor processes and patterns of ongoing habitat change in rapidly changing mountain environments.展开更多
Topographic feature points and lines are the framework of topography,and their spatial distance relationship is an breakthrough in the study of topographical geometry,internal structure and development level.Proximity...Topographic feature points and lines are the framework of topography,and their spatial distance relationship is an breakthrough in the study of topographical geometry,internal structure and development level.Proximity distance(PD)is an indicator to describe the distance between the gully source point(GSP)and the watershed boundary.In the upstream catchment area,PDs can be expressed by the streamline proximity distance(SPD),as well as by the horizontal proximity distance(HPD)and the vertical proximity distance(VPD)in the horizontal and vertical dimensions,respectively.The series of indicators(e.g.,SPD,HPD and VPD)are important for quantifying the geomorphological development process of a loess basin because of the headward erosion of loess gullies.In this study,the digital elevation model data with 5 m resolution and a digital topographic analysis method are used for the statistical analyses of the SPD,VPD and HPD in 50 sample areas of 6 geomorphic types in the Loess Plateau of northern Shaanxi.The spatial characteristics and the influencing factors are also analysed.Results show that:1)Central tendencies for the HPDs and the VPDs for the whole study area and the six typical loess landforms are evident.2)Spatial patterns of the HPDs and the VPDs exhibit evident trends and zonal distributions over the whole study area.3)The HPDs have a strong positive correlation with gully density(GD)and hypsometric integral.The VPDs also correlates with GD to an extent.Vegetation cover,mean annual precipitation and loess thickness have stronger effects on the VPD than on the HPD.展开更多
【目的】地貌是地球表层系统最重要的自然地理要素,其形态划分对地学空间分异研究具有重要意义。【方法】以山西省西山矿区作为研究区,利用该区ALOS 12.5 m DEM数据,通过窗口递增分析和均值变点分析得到地形因子最佳分析窗口为13×1...【目的】地貌是地球表层系统最重要的自然地理要素,其形态划分对地学空间分异研究具有重要意义。【方法】以山西省西山矿区作为研究区,利用该区ALOS 12.5 m DEM数据,通过窗口递增分析和均值变点分析得到地形因子最佳分析窗口为13×13(0.0264 km^(2));利用相关性分析获得最佳地形因子为地形起伏度、海拔高度、坡度、地表切割深度和地表粗糙度;利用区域统计分析得到典型地形因子的分布状况,结合叠加分析提取了西山矿区30种地貌类型,其中浅切割陡小起伏中山为主要地貌,占总面积比为21.23%.【结果】通过与1∶100万地貌类型图的图斑数和地貌分类界线对比,得出地貌类型增加了21类,图斑数目增加了296个,分类界线更为准确,验证了研究结果具有一定可靠性和可行性。【结论】本地貌划分方法较以往更加科学可行,为进一步研究西山矿区灾害防治、开发利用等问题提供了数据参考。展开更多
基金Financial support was provided by the Virginia Tech, Department of Geography, Sidman P. Poole Endowment
文摘Glacier recession is a globally occurring trend. Although a rich body of work has documented glacial response to climate warming, few studies have assessed vegetation cover change in recently deglaciated areas, especially using geospatial technologies. Here, vegetation change at two glacier forefronts in Glacier National Park, Montana, U.S.A.was quantified through remote sensing analysis,fieldwork validation, and statistical modeling.Specifically, we assessed the spatial and temporal patterns of landcover change at the two glacier forefronts in Glacier National Park and determined the role of selected biophysical terrain factors(elevation, slope, aspect, solar radiation, flow accumulation, topographic wetness index, and surficial geology) on vegetation change(from nonvegetated to vegetated cover) at the deglaciated areas.Landsat imagery of the study locations in 1991, 2003,and 2015 were classified and validated using visual interpretation. Model results revealed geographic differences in biophysical correlates of vegetation change between the study areas, suggesting that terrain variation is a key factor affecting spatialtemporal patterns of vegetation change. At Jackson Glacier forefront, increases in vegetation over some portion or all of the study period were negatively associated with elevation, slope angle, and consolidated bedrock. At Grinnell Glacier forefront,increases in vegetation associated negatively with elevation and positively with solar radiation.Integrated geospatial and field approaches to the study of vegetation change in recently deglaciated terrain are recommended to understand and monitor processes and patterns of ongoing habitat change in rapidly changing mountain environments.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41871288, 41930102 and 41602182)the Fundamental Research Funds for the Central Universities (Grant No. 2018CSLZ002)
文摘Topographic feature points and lines are the framework of topography,and their spatial distance relationship is an breakthrough in the study of topographical geometry,internal structure and development level.Proximity distance(PD)is an indicator to describe the distance between the gully source point(GSP)and the watershed boundary.In the upstream catchment area,PDs can be expressed by the streamline proximity distance(SPD),as well as by the horizontal proximity distance(HPD)and the vertical proximity distance(VPD)in the horizontal and vertical dimensions,respectively.The series of indicators(e.g.,SPD,HPD and VPD)are important for quantifying the geomorphological development process of a loess basin because of the headward erosion of loess gullies.In this study,the digital elevation model data with 5 m resolution and a digital topographic analysis method are used for the statistical analyses of the SPD,VPD and HPD in 50 sample areas of 6 geomorphic types in the Loess Plateau of northern Shaanxi.The spatial characteristics and the influencing factors are also analysed.Results show that:1)Central tendencies for the HPDs and the VPDs for the whole study area and the six typical loess landforms are evident.2)Spatial patterns of the HPDs and the VPDs exhibit evident trends and zonal distributions over the whole study area.3)The HPDs have a strong positive correlation with gully density(GD)and hypsometric integral.The VPDs also correlates with GD to an extent.Vegetation cover,mean annual precipitation and loess thickness have stronger effects on the VPD than on the HPD.
文摘【目的】地貌是地球表层系统最重要的自然地理要素,其形态划分对地学空间分异研究具有重要意义。【方法】以山西省西山矿区作为研究区,利用该区ALOS 12.5 m DEM数据,通过窗口递增分析和均值变点分析得到地形因子最佳分析窗口为13×13(0.0264 km^(2));利用相关性分析获得最佳地形因子为地形起伏度、海拔高度、坡度、地表切割深度和地表粗糙度;利用区域统计分析得到典型地形因子的分布状况,结合叠加分析提取了西山矿区30种地貌类型,其中浅切割陡小起伏中山为主要地貌,占总面积比为21.23%.【结果】通过与1∶100万地貌类型图的图斑数和地貌分类界线对比,得出地貌类型增加了21类,图斑数目增加了296个,分类界线更为准确,验证了研究结果具有一定可靠性和可行性。【结论】本地貌划分方法较以往更加科学可行,为进一步研究西山矿区灾害防治、开发利用等问题提供了数据参考。
