1947～2007年上海中心城区居住空间分异变化——基于居住用地类型视角

采用4种分异度测度模型,在街坊尺度和乡镇尺度下,对上海中心城区1947～2007年11个时相的各类居住用地空间分异程度进行计算。发现1949年后各类居住用地分异度呈现不同的波动过程。不同时期居住用地总体分异程度的计算表明,1949年前空间分异严重,计划经济时期有所降低,转型期则又明显上升。不同时期居住用地等级高低与其分异度大小呈现不同的结构特征,1949年前高等级居住用地分异度高、中低等级居住用地分异度较低,形成"一高两低"结构;计划经济时期则是居住用地等级越高,分异度越大的"正相关"结构;90年代后则是最高和最低等级的居住用地分异度高,而中等居住用地分异度最低的"V"型结构。不同时期居住用地空间分异结构特征间的演进,直接原因是新式住宅的建设和旧城的改造,深层次原因则是土地使用制度的变迁和城市空间组织模式的转变。     

Calibration and validation of a model of forest disturbance in the Western Ghats,India 1920–1990

This paper introduces a new statistical method that we recommend should become standard procedure to quantify the goodness-of-fit of calibration and validation for land-use change models. We present a multiple-resolution Relative Operating Characteristic (ROC) that measures the goodness-of-fit between a reference map, which is considered reality, and a simulated map, which is a model’s output. This proposed ROC is based on: (1) multiple-resolutions, (2) soft classification, (3) sampling without replacement, and 4) explicit separation of factors of quantity versus location of land-use change. We illustrate the method with a case study in India’s Western Ghats, a biodiversity hotspot, where we have maps of cumulative forest disturbance for 1920 and 1990. We use a predictive modeling approach similar to GEOMOD in which we calibrate the model with the map of 1920, then predict the map of 1990, at which point we subject the model to validation. We show that the fit of calibration tends to be much larger than the fit of validation. Thus if a modeler assess a model by goodness-of-fit of calibration only, then the modeler will likely be over confident in the model’s predictive ability.     

Impacts of LUCC processes on potential land productivity in China in the 1990s

Land resources (quantity and quality) and climate condition are two of the most important factors that regulate regional agriculture productivity. Climate and land-use have had great changes in the past decades, and hence are expected to impact crop productivity significantly. Climate change will affect crop produc-tivity through alterations of, for example, light, heat, temperature, precipitation. Land-use and land-cover change (LUCC) directly affects potential land produc-tivity by changin…     

西双版纳地区公路两侧土地利用变化格局特征

根据西双版纳地区1976、1988和2003年三期LandsatMSS/TM/ETM影像解译的土地利用数据,运用Arc-G IS软件的缓冲区分析方法,分析该区内主干公路两侧土地利用变化的时空格局。结果如下:27 a间,与整个西双版纳州相比,主干公路两侧的土地利用强度更大、增长速度更快。公路两侧的土地利用转化主要表现为由林地向橡胶园和茶园转变,林地锐减,橡胶园迅速增加,林地是橡胶园的最主要来源。主要地类的面积在一定范围表现出与距公路距离的相关关系,距公路越近,林地面积百分比越小,橡胶园、建筑用地和水田面积百分比越大。土地利用变化也表现出明显的公路效应,距离公路越近,林地减少的速度、橡胶园增加的速度越快;随着距离的增加,林地向橡胶园的转化面积逐渐减小。土地利用变化的公路效应深度表现出不断扩展的趋势:1976年为公路两侧5 km,1988年为7 km,2003年达11 km。     

Fire and vegetation history during the last 3800 years in northwestern Montana

Foy Lake in northwestern Montana provides a record of annual-to-decadal-scale landscape change. Sedimentary charcoal and pollen analyses were used to document fire and vegetation changes over the last 3800 years, which were then compared to similar records from AD 1880 to 2000. The long-term record at Foy Lake suggests shifts between forest and steppe as well as changes in fire regime that are likely the result of climate change. Fire activity (inferred from the frequency of charcoal peaks) averaged 18 fire episodes/1000 years from 3800 to 2125 cal year BP, and increased from 16 fire episodes/1000 years at 2125 cal year BP to 22 episodes/1000 years at 750 cal year BP, a period when the pollen data suggest that steppe vegetation yielded to increasing patches of forest cover. Between 2125 and 750 cal year BP, increased forest cover produced more background charcoal than before and after this period, when vegetation was dominated by steppe. Between 750 and 75 cal year BP steppe has expanded and fire episode frequency averaged 33 episodes/1000 years, increasing to a maximum of 40 episodes/1000 years at ca. 300 cal year BP and then decreasing to present levels. Since AD 1880, the pollen record indicates an increase in shrubs and grasses from AD 1895 to 1960 as a result of vegetation changes associated with timber harvesting and livestock grazing. No fires have been documented in the Foy Lake watershed since AD 1880. Charcoal from the extralocal fires of AD 1910, burning over 4,111,249 ha in Idaho, Montana, and Wyoming, however, is present in Foy Lake. Between AD 1970 and 2000, increased arboreal pollen in the record is consistent with observations that the forest has become more closed. The activities of Euro–Americans have led to a decline in forest cover between AD 1880 and 1970, followed by a recent increase as trees are now growing in areas previously occupied by steppe. Euro–Americans are likely the cause of a reduction in fire activity in watershed since AD 1880.     

Impact of land-use change on hydrological processes in the Maying River basin, China

Since the 1960s, dramatic changes have taken place in land-use patterns characterized by the persistent expansion of cultivated land and a continuous decrease in natural woodland and grassland in the arid inland river basins of China. It is very important to assess the effects of such land-use changes on the hydrological processes so vital for water resource management and sustainable development on the catchment scale. The Maying River catchment, a typical arid inland watershed located in the middle of the Hexi Corridor in northwest China, was the site chosen to investigate the hydrological responses to land-use changes. The annual runoff, base flow, maximum peak flow, and typical seasonal runoff in both spring and autumn flood periods were selected as the variables in the hydrological processes. Statistical-trend analysis and curvilinear regression were utilized to detect the trends in hydrological variables while eliminating the climatic influence. The relationship between cultivated land-use and hydrological variables was analyzed based on four periods of land-use variation data collected since 1965. A runoff model was established composed of two factors, i.e., cultivated land use and precipitation. The impact of land use changes, especially in the large ar- eas of upstream woodland and grassland turned into cultivated lands since 1967, has resulted in a mean annual runoff decrease of 28.12%, a base flow decline of 35.32%, a drop in the maximum peak discharge of 35.77%, and mean discharge decreases in spring and autumn of 36.05% and 24.87% respectively, of which the contribution of cultivated land expansion to the influence of annual runoff amounts to 77%-80%, with the contribution to the influence of spring discharge being 73%-81%, and that to the influence of base flow reaching 62%-65%. Thus, a rational regulation policy of land use patterns is vitally important to the sustainable use of water resources and the proper development of the entire catchment.     

Leimavo Revisited: Agrarian Land-Use Change in the Highlands of Madagascar

Describing and explaining land-use change is of critical concern in Madagascar, where land transformations such as deforestation and resulting environmental degradation currently capture widespread attention. While the eastern rain forest recedes in the face of swidden cultivators, the highlands demonstrate more constructive transformations. In this paper I present a case study of land-use change in Leimavo, a small village near Ambositra studied in the 1960s by Jean-Pierre Raison. Here, the twentieth century has seen a gradual reduction in irrigated rice cultivation and cattle husbandry, and a boom in market-oriented orange, vegetable, and grain production. In the long term, a historical landscape of grassy hills has been transformed into a productive cultural landscape with woodlots, anti-erosion benching, rice terraces, fruit groves, and diverse crops. Critical factors determining the trajectory of land-use change include regional population pressure, state policies, market incentives, climate variations, and access to land and water resources. These critical factors, or explanations, are linked in the discussion by the use of a simple heuristic device—the range of choice—as a theoretical framework.     

Recognition of the 1811–1812 New Madrid earthquakes in Reelfoot Lake, Tennessee sediments using pollen data

Reelfoot Lake is located within the New Madrid Seismic Zone, a region characterized by ongoing seismic activity and the locus of a series of large earthquakes (m _b >7) during 1811–1812. Coseismic uplift and subsidence from the 1811–1812 events formed the lake basin from a partially inundated alluvial bottomland forest. Lithologic, chronologic, and palynologic data from a vibracore are used here to characterize the 1811–1812 earthquake record in lacustrine sediments. The stratigraphic record consists of a poorly consolidated upper silt, an intervening 10-cm sand layer, overlying a compact lower silt. Calibrated radiocarbon age estimates on wood samples from both silt units indicate deposition during historical time (1490–1890 AD).Better age estimates were obtained by correlating pollen assemblage data from the upper and lower silt with the historical record of land-use change in the Reelfoot Lake region. Two factors resulted in changing plant distributions (and hence pollen assemblages) in Reelfoot Lake sediments: 1) altered drainage patterns of Reelfoot Creek and Bayou de Chien resulting from 1811–1812 uplift and subsidence, and 2) deforestation and subsequent cultivation beginning approximately 1850 AD. The upper silt is characterized by a oak/cedar arboreal pollen (AP) assemblage, showing a mixture of upland and alluvial bottomland AP influx from the region to the open lake basin. Non-arboreal pollen (NAP) in the upper silt shows increasing abundance of Composites, particularly ragweed pollen indicating cultivation. This unit was deposited after the 1811–1812 earthquakes. The intervening sand layer was apparently emplaced by earthquake activity, or represents colluvium derived from most recent (1811–1812) coseismic uplift of Reelfoot scarp, which forms the western margin of the lake. The lower silt is characterized by a baldcypress/cedar AP assemblage with minor percentages of other flood-tolerant AP genera, interpreted as a baldcypress-dominated bottomland forest. Pollen influx in this environment is dominated by gravity-component deposition from local sources. The NAP in the lower silt shows that ragweed is rare or absent, suggesting pre-settlement conditions and deposition prior to 1811–1812.This is the 15th in a series of papers published in this special AMQUA issue. These papers were presented at the 1994 meeting of the American Quaternary Association held 19–22 June, 1994, at the University of Minnesota, Minneapolis, Minnesota, USA. Dr Linda C. K. Shane served as guest editor for these papers.     

土地利用的人地关系透视

人地关系的协调是可持续发展战略的基本内容，土地利用是人地关系的核心问题。文章基于对土地综合体属性的把握，分析了土地在人地系统中的基础作用。不同的土地利用类型决定了人地系统的属性特征具有自然和社会两重属性。从土地开发的历史角度探讨了人类系统的发展及其在人地关系构建中的主导作用，最后得出了人地系统的作用机制。     

巫山县近30a来土地利用动态变化及过程

用MSS底片和TM图像作为数据源,通过扫描成像、假彩色合成和空间配准以形成彩色遥感图像。RS和GIS相结合,从卫星图像解译出土地资源利用类型,利用ARC/INFO进行自动统计,并输出各类土地面积,对巫山县近30a来土地利用动态变化进行研究。得出巫山县30a的土地利用变化和环境变化规律,并对造成这种变化的驱动力进行探讨和分析。为今后更加合理地利用土地和相关土地政策的制定提供了决策支持。