基于分形维数和信息熵的土地利用景观格局变化研究——以西安市为例

信息熵和分形理论为研究地理学中系统的有序性和复杂结构现象的不稳定性提供了一条新途径,为研究土地利用景观格局变化提供了新的思路。以信息熵和分形理论为指导,在遥感和GIS技术支持下,对西安市土地利用景观格局演变的分形特征和信息熵进行分析,结果表明:1999-2008年,西安市土地利用景观结构趋于简单化,景观类型在空间上的稳定性逐渐增大;土地利用景观结构信息熵总体上呈逐渐下降趋势,即土地利用有序度逐渐上升,而无序度逐渐降低。     

基于GIS和景观生态学的土地整理景观研究

运用GIS技术和景观生态学理论方法,以安徽省淮南市潘集区市级投资重点土地整理项目为例,选取3类景观指标,对项目区内土地整理前后的土地利用现状和景观格局变化情况进行研究。结果表明： 景观类型中水田斑块占绝对优势,斑块分维数、形状指数呈下降趋势,表明斑块形状趋于规则和简单; 斑块数量和斑块密度降低,平均斑块面积和最大斑块面积增加,最大斑块指数增大,景观破碎度降低; 平均分维数和平均形状指数增大,表明景观形状较整理前变得规则,但总体形态变得复杂; 多样性指数和均匀度指数降低,表明在增加了景观分布均匀程度的同时降低了景观的多样性,景观类型有所减少。     

长沙市景观破碎化时空分异特征研究

基于2000年长沙市1:10万土地利用图,利用ERDAS软件对1989年、2006年的遥感图像进行解译;在地理信息系统软件ArcGIS和景观格局分析软件Fragstats支持下,以城镇建设空间重心为中心,分别选取东西、南北景观样带(40 km×8 km)和8个不同半径的同心圆缓冲区,用斑块密度、边界密度、平均斑块分维数...     

Spatio-temporal changes in land cover and aquatic macrophytes of the Danube floodplain lake

The aquatic vegetation of ?í?ov Lake in the Danube floodplain, which is listed in the Ramsar Convention, was investigated to address three main questions: (1) how have landscape composition and the structures of the lake and its buffer zone changed from the mid-20th century; (2) how have species richness and the abundance of the aquatic macrophyte assemblage in this lake ecosystem changed over the last 34 years; and (3) which landscape metrics can best explain these temporal changes for floating-leaved macrophytes? Two methodological approaches, remote sensing and botanical field surveys, were applied. Historical (1949, 1970, 1990) and contemporary (2006) aerial photographs were analysed to determine land cover. Landscape configuration and structure were analysed using eight landscape metrics selected in advance to measure spatio-temporal changes and the fragmentation of the lake ecosystem and its corresponding buffer zone. The species diversity, abundance and distribution of true aquatic macrophytes were surveyed eleven times in five survey stretches between 1973 and 2007.At the landscape level, a decrease in the area covered by floating-leaved macrophytes, as well as an increase in open water surface and fragmentation of the land cover classes in the lake ecosystem, were recorded from 1949 to 2006. Overall, 30 true aquatic macrophytes were found from 1973 to 2007. Species richness did not change considerably, but the abundance of aquatic species fluctuated over the years. Three groups of true aquatic vegetation, based on common structural characteristics, were found in 1973–1983, 1989–2002, and 2004–2007 over the last 34 years. The landscape metrics NP, PD, LPI, and SHDI, which all express patterns of landscape fragmentation mostly indicate temporal changes in floating-leaved macrophytes.     

Evaluating geological heritage: correspondence on Ruban, D.A. ‘Quantification of geodiversity and its loss’ (PGA, 2010, 121(3): 326-333)

This article comments on the recent paper in this journal by Ruban (2010) which presented a simple quantitative scheme for the calculation of landscape geodiversity and its application to evaluating geodiversity between different locations. This comment article highlights some conceptual and methodological issues in the set-up and application of Ruban's scheme, and suggests that geodiversity as a measure can only be meaningful if it is set within a wider context of landscape and geological conservation and management. Some examples of conservation strategies in Great Britain are described in order to illustrate this wider context.     

Geologic time scales in modern books: a failure of standardization?

This is a response to the Correspondence by Knight (Proceedings of the Geologists’ Association, 2011) entitled ‘Evaluating geological heritage’. In this response I suggest that geodiversity can be evaluated (1) conceptually as a natural treasure within landscape, cultural, and historical contexts and (2) numerically as a number of geosite types (not as a number of geosites). These points of view are not conflicting, but mutually profitable. Moreover, broad context and perception of geodiversity can be involved in its quantification. Geodiversity is viewed as a dynamic idea, which modifications will be reflected in every study of the regional geological heritage.     

Multi‐process Late Quaternary landscape evolution modelling reveals lags in climate response over small spatial scales

Landscapes evolve in complex, non‐linear ways over Quaternary timespans. Integrated geomorphological field studies usually yield plausible hypotheses about timing and impact of process activity. Landscape Evolution Models (LEMs) have the potential to test and falsify these landscape evolution hypotheses. Despite this potential, LEMs have mainly been used with hypothetical data and rarely to simulate the evolution of an actual landscape. In this paper, we use a LEM (LAPSUS: LandscApe ProcesS modelling at mUlti dimensions and scaleS) to explore if it is possible to test and falsify conclusions of an earlier field study on 50 ka landscape evolution in Okhombe Valley, KwaZulu Natal, South Africa. In this LEM, five landscape processes interact without supervision: water driven erosion and deposition, creep, solifluction, biological weathering and frost weathering. Calibration matched model results to three types of qualitative fieldwork observations: individual process activity over time, relative process activity over time and net landscape changes over time. Results demonstrate that landscape evolution of the Okhombe valley can be plausibly simulated. A particularly interesting and persistent feature of model results are erosional and depositional phases that lag climatic drivers both by decades, and by several ka within a few hundred meters. The longer lag has not been reported for this spatial scale before and may be an effect of slow landscape‐soil‐vegetation feedbacks. The combined modelling and fieldwork results allow a more complete understanding of these responses to climate change and can fill in hiatuses in the stratigraphical record. Suggestions are made for methodological adaptations for future LEM studies. Copyright © 2009 John Wiley & Sons, Ltd.     

An integrated lake-catchment approach for determining sediment source changes at Aqualate Mere,Central England

This paper raises fundamental questions about the sole use of paleolimnological techniques to identify sediment sources and develop catchment management plans. The concept of an integrated lake: catchment framework was established 30 years ago, yet paleolimnologists occasionally fail to appreciate the dynamics of the contributing catchment. This is especially critical when the predominant source of sediment accumulating in a lake is allochthonous. In this paper we argue that a detailed appraisal of catchment sources and investigation of historical documentary evidence is needed to identify and evaluate the relative significance of sediment sources. We used such an approach at Aqualate Mere, Shropshire, UK. Mineral magnetic and radionculide signatures of potential catchment sources and accumulating lake sediments were compared in an attempt to match the sources to sediments deposited in the Mere. Dated lake sediments indicate there has been an increase in sedimentation rate and the relative amount of minerogenic material delivered to the Mere over the last 200 years. In contrast to a previous study at the same site, there is no evidence to attribute this increase to an overspill from a nearby canal. Other catchment disturbances include landscaping in parkland surrounding the Mere in the early nineteenth century and drainage systems installed to improve catchment agriculture over the last ca. 150 years. Both activities may explain the change in sedimentation rates and types, independent of the hypothesized canal origin. Although our results exclude the canal as a major sediment source, identifying the contribution of other potential catchment sources remains problematic. ¹³⁷Cs inventories for the lake are similar to those recorded at a local reference site, suggesting little influx of ¹³⁷Cs-bearing topsoil, yet ¹³⁷Cs activities remain high in the upper 20–30 cm of the lake sediment profile, indicating a topsoil origin. Combined radionuclide and mineral magnetic signatures proved to be relatively poor discriminators of potential sources, and the high atmospheric pollution load from the West Midland conurbation has probably altered recent lake sediment signatures. Although further research is required to identify the origins of recent (last ca. 200 years) minerogenic sediment inputs to the Mere, we suggest that the combined lake: catchment approach offers a more rigorous method for understanding the impact of catchment disturbance than analysis of the paleolimnological record alone.     

The landscape Reynolds number and other dimensionless measures of Earth surface processes

An analogy between turbulent fluid systems and landscape drainage systems [Parker, G., Haff, P.K., Murray, A.B., 2001, EOS, Transactions of the American Geophysical Union, 82, pp. F564.] is suggested by the observation that transport in both systems can be approximated by diffusion with size-proportional effective diffusivities, with a cross-over at small scales to Fickian diffusion. The “landscape” Reynolds number of a typical fluvial landscape is estimated to be of order Re_L 10⁶ to 10⁹, these large values reflecting the relative efficiency of fluvial transport compared to creep. Re_L is the ratio of the large-scale effective diffusivity of rivers to the small-scale diffusivity of creep processes on hillslopes. The spatial dependence of the effective diffusivity produces rivers with logarithmic long-profiles, similar to the profiles of many rivers in nature, and analogous to the logarithmic dependence of mean fluid velocity on distance from a wall in turbulent flow. The landscape example suggests how other generalized “Reynolds numbers” can be constructed as ratios of large-scale to small-scale diffusivities to measure the efficiencies of complex processes that affect the surface. As an example, the global airline transportation network is estimated to have an efficacy relative to that of direct human mechanisms for transport of similar goods and materials of about 10⁸ as measured by a corresponding “technology” Reynolds number. The appearance of such large dimensionless numbers, pertaining to the consequences of human invention and design, reflects the emergence of the technosphere as an increasingly efficient overlay on the historical domain of biology and surficial geology.     

汕头市土地利用空间格局的景观生态学分析

根据不同利用类型土地生态效应的异同,对汕头市2003年1∶1万比例尺土地更新调查数据的土地分类系统进行调整,将全部土地景观划分为耕地、林地、园地、草地、居民点及工矿、交通、裸土地和水域等8类.在GIS的支持下,提取各类型土地景观斑块的数目、面积和周长等信息,据此对斑块景观的数量、面积和形状等特征,以及区域景观的多样性、均匀度和优势度,集中性和区际意义等进行分析,从而总结出全市范围及六区一县土地利用空间格局的景观生态学特征.