Environmental dust: A tool to study the patina of ancient artifacts

Dust is a significant, albeit under-recognized, component of ancient patinas that accumulates on exposed surfaces of artifacts. Dust storms are ubiquitous in the Levant; however, often unnoticed substances such as minerals, microfossils and pollen can be found within the patina of an artifact, preserving its geological signature. Modern anthropogenic aerosol sources are often characterized by the presence of heavy metals. Pollen from fruits and shrubs that are not indigenous, if found in the patina, can be used to differentiate recent artifacts from those of antiquity. Archaeological materials that are exposed to local environmental and depositional processes in a tel, a cave or soil, may accrete in a patina over time and may have some dust components reflective of the environmental record. The scores of unprovenanced looted antiquities have necessitated the need to differentiate a genuine artifact from a modern fraud. Since the geological component of the dust in the Levant is known, and the climate and its attendant wind patterns apparently were quite constant during recent millennia times, the dust in the patinas of a true artifact is easy to differentiate from patinas containing modern dust. Both contemporary and historical dust can serve as tools to authenticate an artifact.     

土地利用动态变化研究方法探讨

本文从全球变化的研究热点--“土地利用/土地覆盖变化”的涵义及研究内容出发,概括分析了土地利用变化研究的方法-土地利用变化模型的建立,阐述了各类模型的涵义及在土地利用变化研究中的意义,并重点介绍了定量研究土地利用动态变化的几种模型-（1）土地资源数量变化模型;（2）土地资源生态背景质量变化模型;（3）土地利用程度变化模型;（4）土地利用变化区域差异模型;（5）土地利用空间变化模型;（6）土地需求量预测模型。     

Land cover changes during agrarian restructuring in Northeast China

During the last quarter of the 20th century the agrarian sector in China went through a series of reforms. Changes in government policy on land use led to extensive changes in land cover, culminating in the 1990s. These changes were detected from multi-temporal Landsat TM images of 1990, 1995 and 2000 for Northeast China. Overlay of the mapped land cover in ArcInfo showed that farmland and grassland decreased while water, built-up areas, and woodland increased. More than three-quarters of the detected changes occurred during 1990–1995. Farmland changed mainly to woodland, water, and built-up areas while woodland and grassland were converted chiefly to farmland. Spatially, the change from woodland to farmland adjoined the margin of natural forests while change in the opposite direction was restricted to the agropastoral west. Paradoxically, reclamation of grassland to farmland also took place in the agropastoral west. These conflicting changes were caused primarily by lack of stability and consistency in the government's land use policies.     

Forest cover change and land tenure change in Mexico’s avocado region: Is community forestry related to reduced deforestation for high value crops?

Forest cover change in highland pine-oak forests of Michoacan, Mexico is due to a process of conversion of natural forests to avocado orchards. Privately-owned avocado orchards are found on land that was common forest before the 1992 Reform of the Mexican Constitution. We ask how forest cover change was facilitated by policy changes that affected land tenure rules and existing community forestry programs. We use a comparative case study of four communities, an analysis of forest cover change, and interviews and household surveys. Results show that 33.1% of forest cover was lost over a 16-year-period across the region. However, two forestry case study communities lost 7.2% and 15.1% of forest cover, while two adjacent non-forestry communities lost 86.5% and 92.4%, respectively. Interview data show that the Reform of Article 27 combined with the 1992 Forestry Law led to collapse of local governance, illegal division of common forests, and illegal logging in the two non-forestry communities.     

Shifting farming-pastoral ecotone in China under climate and land use changes

Meteorological records show a rise in temperature and decrease in precipitation in most parts of the farming-pastoral ecotone of Northern China over the last 50 years. During the last quarter of the 20th Century, the agrarian sector went through a series of reforms and changes in government policies on land use that have led to extensive changes in land cover. The objective of this study was to redefine the location and analyze the boundary variations under the effects of climate and land use changes in the farming-pastoral ecotone of Northern China. The results showed that the location of study area has been redefined as both a climatic ecotone from the perspective of suitability of precipitation and temperature for agricultural crops and vegetation growth, and also a land use ecotone based on the impacts of farmland restructuring by government policies on land use. In recent decades, the climatic boundary has moved southeast while the land use boundary has moved northwest, showing opposing directions of change. The extent of boundary changes in the northeast and northern sections are far greater than in the northwestern section of the farming-pastoral ecotone of Northern China.     

Combining land transitions and trajectories in assessing forest cover change

One restriction of landscape studies is that land use and cover change is often regarded as irreversible. A highly dynamic landscape in southern Chile was selected to show that forest cover change involves a series of complex transitions and trajectories. Using Landsat images from 1976, 1985, 1999 and 2007 an in-depth analysis of the transition matrix was conducted to separate random and systematic transitions which were grouped into trajectories using a pixel-history approach. Main trajectories were linked to fragmentation indices and farming systems through cluster analysis. Of the 247 trajectories identified, old growth forest persistence comprised 22% of the landscape, whereas deforestation trajectories comprised 20.9% and were mostly composed of changes from old growth forest to shrubland (13.9%). Trajectories of forest degradation from old growth to secondary forest comprised 19.7% of the landscape. The periods 1976-1985 and 1999-2007 concentrated the most systematic deforestation and degradation transitions. In turn, random transitions predominated between 1985 and 1999, probably in response to economic factors that acted suddenly on the landscape during the 80’s, such as the woodchip export and aquaculture booms. A close relationship between landscape fragmentation and the proportion of systematic transitions and farming systems was found; specifically, the highest entropy indices occurred in clusters which exhibited the lowest proportion of systematic transitions and the highest proportion (>70%) of peasant agricultural systems. Understanding the complexity of forest cover change trajectories is relevant for improving the prediction of possible landscape evolutions and establishing landscape management priorities.     

Forest Clearing Among Farm Households in the Maya Biosphere Reserve*

Central America's tropical forests have been felled more rapidly than those of any other world region during the latter half of the twentieth century. During this time, nearly half of Guatemala's forests were eliminated. Most of this deforestation has been concentrated in the northern department of Petén. The remaining forests in Petén are now mainly concentrated in the Maya Biosphere Reserve (MBR), the heart of the largest lowland tropical forest in Central America. The pace, magnitude, and geography of this trend is of critical importance to forest conservation and rural development efforts. This article examines socioeconomic, political, demographic, and ecological factors behind settler land use and forest clearing among 241 farm households in the Sierra de Lacandón National Park (SLNP), a core conservation zone of the MBR. Some of the factors positively related to forest clearing were household size, Q'eqchí Maya ethnicity, land owned in the previous residence, farm size, land title, and the cropping of velvet bean as a soil amendment. Education, off‐farm employment, and farm distance to a road were negatively related to farm‐level deforestation.     

植物入侵与其它全球变化因子间的相互作用

全示变化包括大气臭氧层的损耗，CO2等温室气体排放增加，气候增暖，土地利用和覆盖变化。生物多样性丧失以及外来种入侵等因子，植物入侵与其它全球性变化因子间有复杂的相互作用；大气CO2浓度增加将导致C3植物比C4植物竞争力更强，低营养生态系统会变得更易入侵，变化的气候条件下，许多种类面临迁移或外来问题，土壤变暖也将使许多休眠植物改变习性，增加紫外辐射将使一些植物的生长和生产力减少。进而会对其竞争和生态过程有间接的影响，CO2浓度升高时硫酸盐的沉积可以增强C3植物的竞争力，较致密的生境破碎化后，一些入侵种可通过边缘进一步向群落内部入侵，增加或降低典型干扰的频率和强度及引入新干扰，能促进外来种的定居和扩散，植物，动物和微生物间的关系改变对植物入侵的速率和效果有明显影响，世界性贸易和运输为生物的入侵提供了条件。     

1990—2005年疏勒河流域土地利用/覆盖变化分析

选择疏勒河流域为研究区域,利用1990年TM、2000年ETM和2005年TM影像为信息源,应用地理信息系统和遥感技术,提取三期疏勒河流域土地利用信息,并对土地利用动态进行了分析。结果表明,近15 a来,疏勒河流域土地利用变化缓慢,土地利用格局没有发生显著变化;不同土地利用类型中,耕地面积和建设用地增加较多;林地、草地面积减少;水域在1990—2000年间减少,2000—2005年间增加;未利用地在1990—2000年之间增加,2000—2005年之间减少。     

城市土地利用空间变化趋势研究--以广州市海珠区为例

对研究区内不同年份的土地利用图进行叠置等空间信息处理运算,获得3个时段土地利用的空间变化图,将一个网格图层分别与3个时段的土地利用变化图叠加,分析各空间单元的年均变化强度指数,得到土地利用的空间变化结果.然后对年均变化强度指数进行分级统计后得到二级用地类型的土地利用空间变化情况,并结合社会经济因素加以分析,得到研究区3个不同时段的土地利用空间变化趋势.最后对主要二级用地类型的时空结构演变情况进行概括性的分析和评价.     

洞庭湖区近20年土地利用/覆盖变化的时空特征

在中国资源与环境时空数据库的支持下,利用20世纪70年代末期、80年代末期和90年代末期获取的陆地资源卫星图像和GIS分析方法,对洞庭湖区近20年的土地利用/覆盖变化的时空特征进行了研究。结果表明,变化比较显著的地类有3种:耕地减少了1 97%,各类建设用地总计增加了14 88%,水域面积增加的幅度为8 77%。耕地与水域相互之间的转变比较频繁。以80年代末为界,前后2个10年间,建设用地、水域和草地的面积在2个时期均持续增加,耕地、林地的面积都持续减少。后期土地利用的动态度大于前期;前期动态度最大的县域有岳阳市、沅江县和汉寿县,后期动态度最大的则为石首市、津市和岳阳市,全部为市级行政区或县改市区。     

区域土地利用变化及其对粮食生产影响分析——以山东省为例

土地利用变化及其效应是目前全球变化研究的热点之一。本文以山东省为例,在分析土地利用结构特点和粮食总产量的时间变化趋势的基础上,进一步探讨了土地利用变化对粮食生产的影响。其影响主要表现在:土地利用类型变化与粮食播种面积、土地利用程度变化与粮食总产、土地利用集约度与粮食单产等三个方面。针对上述影响进一步探讨了保障粮食生产可持续发展的措施及土地利用分区,可为区域土地利用取向和制定粮食发展政策提供科学依据。     

Scenarios of land system change in the Lao PDR: Transitions in response to alternative demands on goods and services provided by the land

Sudden and gradual land use changes can result in different socio-ecological systems, sometimes referred to as regime shifts. The Lao PDR (Laos) has been reported to show early signs of such regime shifts in land systems with potentially major socio-ecological implications. However, given the complex mosaic of different land systems, including shifting cultivation, such changes are not easily assessed using traditional land cover data. Moreover, regime shifts in land systems are difficult to simulate with traditional land cover modelling approaches. A novel simulation approach was employed that focused on simulating changes in land systems rather than focusing on land cover. With the CLUmondo model we simulated three scenarios of potential developments between the years 2010 and 2030 assuming different degrees of international market integration and sustainable growth objectives. Although all scenarios show a decline of shifting cultivation systems, the respective orientation of markets and land governance resulted in strongly different land change trajectories. The land system changes are strongly location dependent and different trajectories are found in different parts of the country. Some scenarios show clear elements of land sparing with intensification of land management in the valleys and re-growth of forest on sloping land. Other scenarios show elements of enhanced multi-functionality. The approach addressed methodological challenges in simulating land system regime shifts and complex mosaic landscapes while accounting for societal demands for different types of goods and services from land systems. The land systems approach allows a nuanced representation of different types of forests and agricultural systems such as shifting cultivation and commercial agricultural plantations. Simulation results contribute to a debate about desired future land use on the national scale including its environmental and socio-economic implications.     

区域土地利用结构变化与土地可持续利用研究——以衡阳市为例

研究了衡阳市的土地利用现状和土地利用结构变化的总体特征,预测了2005和2010年衡阳市土地利用结构的变化趋势,以及由此而对该区域土地可持续利用的影响.在未来的10年内,随着社会经济的进步,农村小城镇化的发展,衡阳市耕地资源仍将继续减少,非农建设用地对耕地保护冲击强烈,人为水土流失将进一步增强.据此,提出了衡阳市土地资源可持续利用的政策建议.     

渭河流域3 100年前资源退化与人地关系演变

渭河流域全新世古土壤S     

基于遥感和GIS的松嫩沙地土地利用/土地覆被时空格局研究

利用1986年和2000年2期TM影像资料,建立相应的空间图形库系统,定量分析了松嫩沙地典型区近15a来土地利用数量变化,从土地利用斑块特征、斑块空间邻接关系变化和主导变化类型角度对土地利用/覆被格局进行了清晰的空间描述。结果表明,研究时段内该区土地利用量变和质变活跃。耕地面状成片、条带状延伸和斑块状空间扩展,从整体上呈现集中化特征。较大面积的草地和林地被分割、破碎化,小块盐碱化草地空间聚集与扩张。耕地与草地、草地与盐碱地空间相邻度变大,草地开垦强度增大、土地盐碱化日益严重。空间变化上表现为耕地、林地、草地和未利用地之间相互转化,以草地、林地-旱地,草地-未利用地,未利用地-旱地、水田及旱地-水田最为显著。     

Future landscapes of Switzerland: Risk areas for urbanisation and land abandonment

In Switzerland, the decreasing significance of agriculture has led to prominent processes of land abandonment in mountainous areas where the maintenance of open land relies on human intervention. At the same time, urbanisation in Switzerland is increasing at a rapid rate at the expense of other land use types, particularly open land agriculture. In spite of these observed trends, the extent and location of anticipated land-use changes for the coming 20 years remain unknown, as does the impact on landscape services. This research defines 5 scenarios of future land-use for Switzerland along axes of Globalisation to Regionalisation and Market-driven developments to high policy intervention. Using the Dyna-CLUE land use modelling framework we incorporate socio-economic and bio-geographical variables to model scenarios of land change for 2035. By identifying locations for key land use transitions which occur across several scenarios, we find that unless large scale policy interventions are made, large areas of the Swiss Plateau and Alpine valley bottoms face strong urbanisation and much of the mountainous pasture agriculture continues to face risk of abandonment.     

Land use/land cover change detection and prediction in the north-western coastal desert of Egypt using Markov-CA

Detecting land-use change has become of concern to environmentalists, conservationists and land use planners due to its impact on natural ecosystems. We studied land use/land cover (LULC) changes in part of the northwestern desert of Egypt and used the Markov-CA integrated approach to predict future changes. We mapped the LULC distribution of the desert landscape for 1988, 1999, and 2011. Landsat Thematic Mapper 5 data and ancillary data were classified using the random forests approach. The technique produced LULC maps with an overall accuracy of more than 90%. Analysis of LULC classes from the three dates revealed that the study area was subjected to three different stages of modification, each dominated by different land uses. The use of a spatially explicit land use change modeling approach, such as Markov-CA approach, provides ways for projecting different future scenarios. Markov-CA was used to predict land use change in 2011 and project changes in 2023 by extrapolating current trends. The technique was successful in predicting LULC distribution in 2011 and the results were comparable to the actual LULC for 2011. The projected LULC for 2023 revealed more urbanization of the landscape with potential expansion in the croplands westward and northward, an increase in quarries, and growth in residential centers. The outcomes can help management activities directed toward protection of wildlife in the area. The study can also be used as a guide to other studies aiming at projecting changes in arid areas experiencing similar land use changes.     

LUCC研究的最新进展评述

土地利用/土地覆被变化(LUCC)是全球环境变化的重要组成部分和主要原因之一,进入新世纪以来,LUCC研究一直是地理学研究的前沿与热点。本文综述了2002年8月在南非德班国际地理学联合会(IGU)"2002年区域地理大会"上有关LUCC的主要研究成果,认为国际上LUCC研究在应用RS、GIS技术开展土地利用/土地覆被变化监测、评价与制图;农村与农业土地利用/土地覆被变化分析;城市土地利用/土地覆被变化分析;土地利用/土地覆被变化动力学;土地利用/土地覆被变化与生态环境等五个方面取得最新进展,反映出LUCC研究范围在进一步拓展,研究内容在进一步深化。     

Predicting plausible impacts of sets of climate and land use change scenarios on water resources

Our world is changing at an unprecedented rate in terms of climate and land use, but these changes can affect our water resources. Hence, we need a methodology that can predict both their individual and agglomerative ramifications. Using the Little Miami River (LMR) watershed as a case study, this paper describes a spatial analytical approach integrating mathematical modeling and geographical information sciences to quantitatively examine the relative importance of the separate and combined hydrologic and water quality impacts of climate and land use changes.The Hydrologic Simulation Program - Fortran (HSPF) model was chosen in this study to simulate stream flow and nutrient transport process. Five hypothetical climate change scenarios were used to cover the possible ranges of variability in the year 2050. An enhanced population-coupled Markov-Cellular Automata (CA-Markov) land use model was developed to predict the 2050 land use pattern. When these scenarios were incorporated into the HSPF model, the future conditions in the LMR basin were postulated. The findings demonstrated that: 1) the LMR watershed would experience an increase in flow and nutrients under the 2050 land use projection, 2) stream flow and water quality impacts would be amplified when both climate and land use changes were simultaneously considered, 3) land use change (and in the case of the LMR watershed, urbanization) could help to alleviate water shortage during the dry years, 4) total phosphorus and nitrogen would increase under all future climate and land use scenarios; the highest increase was found under the combined wettest and future land use scenarios, and 5) the described approach is effective in simulating the hydrologic and water quality effects of climate and land use changes in a basin scale. These results are relevant to planners; they can be useful in formulating realistic watershed management policies and mitigation measures.