Role of basin‐wide landslides in the formation of extensive alluvial gemstone deposits in Sri Lanka

The tectonically stable central highlands of Sri Lanka and its alluvial valleys are the source areas and sinks, respectively, for one of the most prolific Quaternary gemstone provinces in the world. However, the known ¹⁰Be/²⁶Al cosmogenic‐nuclide‐determined low natural (preanthropogenic) denudation rates of 2–11 mm kyr^?1, and resulting sediment fluxes, are grossly inadequate to deliver the vast throughputs of overburden required to concentrate the known gemstone deposits. Basin‐wide, unstable, slow‐moving channelized landslides and debris flows, aided by biotic factors, are the dominant mechanisms of mass‐wasting on hill‐slopes and bulk delivery of sediment to the alluvial valleys and fluvial networks. Channelization ensures modulated sediment transfer and run‐out during an erosional–depositional continuum. In a selected inventory of landslides, mobilized sediment volumes ranged from less than 1000 cubic metres to a maximum of ～800 000 cubic metres per event. Monsoonal rainfall (both cumulative seasonal and total daily thresholds) is the primary external factor, which interacts with colluvium thickness and steep slopes in triggering landslides. There are three to five ‘threshold’ rainfall events per year in the highlands that can be expected to generate landslides. They can occur under conditions of decreasing daily rainfall as the seasonal total rainfall increases. GIS databases show a very significant spatial overlap and direct causal linkage between several hundred landslide occurrences and the innumerable gem pits and mines in the catchments of the best known mining region of Sri Lanka. Landslide‐associated mass movements, besides providing significant numbers of gemstones to the alluvial valleys over time, are also a fundamental factor in the geomorphic evolution of the rugged central highland landscape. Rainfall‐driven landslide activity may be a natural geological response affecting erosional equilibrium in high‐relief tectonically stable terrains. Climatically forced base level changes will, over time, control sediment storage, removal or reworking in the valleys. Copyright © 2007 John Wiley & Sons, Ltd.     

风景名胜区三维景观导游系统研制方案的思考

简要介绍了Skyline软件的性能及该软件下的TerraBuilder组件。阐述了使用TerraBuilder组件与3DsMAX相结合制作景区三维景观浏览效果图的方法,介绍了三维景观图的制作过程,强调需要使用photoshop软件来进行后期处理,以得到完美的效果图。     

THE LANDSCAPE ECOLOGICAL ，ASSESSMENT AND PLANNING IN THE CONTOL WATERSHED BY RESERVOIR OF ERLKONG MOUNTAIN

Based on the theories of landscape ecology,landscape eco-environment in the coutrol watershed by reser-voir of Erlong Mountain in Heilogjiang Province was analyzed and assessed by using GIS technique and statistical model of Principal Component Analysis and Spatial Cluster Analysis.It is found that 100.08km^2(36%) of the total area is in the state of kilter,85.73km^2(31%) of the total area is in the state of general,and 47.26km^2(17%) and 15.48km^2(16%) is in the relatively poor state and ideal state.According to landscape ecological structure,there are three land-scape function areas being planned and designed.1) Agricultural landscape function area:its developmental direction is tour agriculture and high-benefit agriculture.2)Eco-environment protected function area:the direction of development and utilization of this region is to develop vigorously forest for soil and water conservation ,and try to increase the rate of vegetation cover.3)Forest landscape function area:rational cut and utilization of forest resources,space optimization disposal of category of forest ,foster of forest and protection of wildwood will become the main development directions for this region.This study trys to provide scientific foundation for ecological restoration of the whole valley and its sustain-able development.     

ANALYSIS ON SPATIAL DIFFERENCE OF LAND USECHANGE BASED ON PHYSICAL AND CULTURALLANDSCAPE ATTRIBUTES──A Case Study at Mongolian AutonomousCounty of Qian Gorlos, Jilin Province

Land use changes are regarded as landscapepattern change driven by many interactive natural andsocial-economic fact6apCQUES, 1999; JOHANN etal., 1999), and show the competition between land usetypes undet different conditions. Socio-economic attributely contribute to lands use/cover change in shortperiod(BENOIT et al., 1999; TURNER et al., 1995 ),whereas physical conditions constrain essential changetendency and change process. The spatial difference inland use dynamic in Mongolian A…     

Spatial gradient analysis of urban green spaces combined with landscape metrics in Jinan City of China

1IN T R O D U C T IO NUrban green spaces can be consideredas the outdoorplacesintheurban covered with significanatmounts ofvegetation,naturalor manmade,as opposed to areasthatare paved or having buildingon them(JIM andC HEN,2003;SHIVANAND and SUZANA,2005)…     

我国沿海滩涂景观生态初步研究

沿海滩涂是一类特殊的土地/景观类型。文中以景观生态学理论为指导,结合我国实际,将沿海滩涂划分为泥滩、砂滩、岩滩和生物滩等四大基本类型。认为沿海滩涂是一种典型的开放系统,具有对干扰敏感、边缘效应明显、自然要素空间集聚、空间动态迁移、空间异质性显著和地域分异等六大景观生态特征,并据此提出沿海滩涂开发的基本准则。     

论战场环境的区域特性

文章从战场景观、战场地域结构、战场物资潜力 3个方面研究战场环境的区域特性。阐述了景观、地域结构、物资潜力的概念内涵 ,并分析它们对战役活动的影响和制约。     

土地利用监测适宜尺度选择方法研究 ——-以塔里木河流域为例

适宜尺度选择是生态学、地理学等学科的重要问题之一。在不同的研究目的下, 尺度选择的方法和标准也随之变化。以塔里木河流域20 世纪50 年代土地利用数据为例, 将面积 作为尺度选择的参数, 统计斑块面积分布直方图, 然后计算9 种比例尺(1:2 000 000, 1:1 000 000, 1:500 000, 1:250 000, 1:100 000, 1:50 000, 1:25 000, 1:10 000 和1:5 000) 下的归一化尺度方差, 最后结合Shannon-Weaver 景观多样性指数、Simpson 多样性指数和分维 数补充归一化尺度方差的结果, 探讨塔里木河流域土地利用的空间分布特征和尺度规律。结果如下: ① 归一化尺度方差值显示塔里木河干流50 年代土地利用监测适宜尺度为1:50 000 比例尺(约20km×20km 网格大小), 除沙地适宜尺度在1:100 000 比例尺外, 有林地、灌木林地和盐碱地的适宜比例尺均在1:50 000 比例尺上; ② Shannon-Weaver 多样性指数、Simpson 多样性指数和分维数结果表明盐碱地的多样性指数的适宜尺度与归一化尺度方差结果相同, 沙地的多样性指数与归一化尺度方差的适宜尺度域相同, 有林地和灌木林地多样性指数最优尺度在1:10 000 比例尺与归一化尺度方差结果不同; ③ 沙地和盐碱地的分维数在1:10 000 比 例尺处有明显的上升, 沙地达到最大值1.35, 而在其他尺度分维数值接近, 有林地和灌木林地则在各个尺度分维数值接近, 且值不超过1.2。     

The Gunnison's prairie dog structures a high desert grassland landscape as a keystone engineer

The influence of landscape spatial structure on ecological processes has recently received much attention. Comparisons are made here between the spatial structure of grasslands, and active and extirpated Gunnison's prairie dog (Cynomys gunnisoni Hollister) towns at the Petrified Forest National Park, Arizona, U.S.A. The spatial structure of bare ground was quatified using a box-counting technique to extract landscape fractal dimensions, D, and bare-ground patch size. These landscapes are fractal, and active prairie dog towns had higher fractal dimensions, i.e. a more homogeneous spatial structure as D approaches 2, than inactive towns, which had higher fractal dimensions than unmodified grasslands. Morisita's index suggested that shrubs were more randomly distributed on prairie dog towns and more aggregated on grassland habitats. The different spatial distributions of bare ground and shrubs have the potential to influence resource distributions between these habitats for both prairie dogs and other fauna. Consequently, the presence of prairie dogs in these grasslands increases grassland landscape heterogeneity at large spatial scales, potentially enhancing beta diversity.     

青眉山溶洞旅游景观的成因分析

介绍了青眉山溶洞的岩溶景观、文物古迹及其旅游开发价值,重点从地史、岩性、地质构造等方面分析了该洞及其景观的成因。研究认为,景观边际效应是该深洞旅游景观形成的主要原因,至于该洞对于全球变化,古气候重建的研究意义,尚待进一步的考证。