Changing land use/cover patterns and implications for sustainable environmental management in the Irangi Hills,central Tanzania

This article examines the changes in land-use/cover types in the Irangi Hills, central Tanzania during the last 45 years and how such changes have influenced environmental and agricultural sustainability in the area. The spatial and temporal changes of land-use/cover were analysed through aerial photographs interpretation. Local perceptions and experiences of changes were addressed through household interviews and field observations. Results from this study show that during the last 45 years open and wooded grasslands, and other tree-cover types covered about 40% of the land area, ranging from 29% in 1960 to 43–45% between 1977 and 1992. Also, during the same period both the total area and spatial distribution of cultivated fields varied greatly. The cultivated area increased from 31% in 1977 to 35% in 1992, mainly due to agricultural expansion into areas formerly used for grazing and in sandy watercourses that shrunk by 55% between 1977 and 1992. The spatial distribution of the different land-use/cover types is influenced by variations in the scale of soil erosion and soil-conservation initiatives implemented in the Irangi Hills since the early 1970s. However, with increasing pressure on the land, and the declining capacity of the soil conservation authority, sustaining agricultural production in the area remains a major challenge.     

Impacts of climate change on land-use and wetland productivity in the Prairie Pothole Region of North America

Wetland productivity in the Prairie Pothole Region (PPR) of North America is closely linked to climate. A warmer and drier climate, as predicted, will negatively affect the productivity of PPR wetlands and the services they provide. The effect of climate change on wetland productivity, however, will not only depend on natural processes (e.g., evapotranspiration), but also on human responses. Agricultural land use, the predominant use in the PPR, is unlikely to remain static as climate change affects crop yields and prices. Land use in uplands surrounding wetlands will further affect wetland water budgets and hence wetland productivity. The net impact of climate change on wetland productivity will therefore depend on both the direct effects of climate change on wetlands and the indirect effects on upland land use. We examine the effect of climate change and land-use response on semipermanent wetland productivity by combining an economic model of agricultural land-use change with an ecological model of wetland dynamics. Our results suggest that the climate change scenarios evaluated are likely to have profound effects on land use in the North and South Dakota PPR, with wheat displacing other crops and pasture. The combined pressure of land-use and climate change significantly reduces wetland productivity. In a climate scenario with a +4 °C increase in temperature, our model predicts that almost the entire region may lack the wetland productivity necessary to support wetland-dependent species.     

Sea-level rise vulnerability in the countries of the Coral Triangle

Sea-level rise is a major threat facing the Coral Triangle countries in the twenty-first century. Assessments of vulnerability and adaptation that consider the interactions among natural and social systems are critical to identifying habitats and communities vulnerable to sea-level rise and for supporting the development of adaptation strategies. This paper presents such an assessment using the DIVA model and identifies vulnerable coastal regions and habitats in Coral Triangle countries at national and sub-national levels (administrative provinces). The following four main sea-level rise impacts are assessed in ecological, social and economic terms over the twenty-first century: (1) coastal wetland change, (2) increased coastal flooding, (3) increased coastal erosion, and (4) saltwater intrusion into estuaries and deltas. The results suggest that sea-level rise will significantly affect coastal regions and habitats in the Coral Triangle countries, but the impacts will differ across the region in terms of people flooded annually, coastal wetland change and loss, and damage and adaptation costs. Indonesia is projected to be most affected by coastal flooding, with nearly 5.9 million people expected to experience flooding annually in 2100 assuming no adaptation. However, if adaptation is considered, this number is significantly reduced. By the end of the century, coastal wetland loss is most significant for Indonesia in terms of total area lost, but the Solomon Islands are projected to experience the greatest relative loss of coastal wetlands. Damage costs associated with sea-level rise are highest in the Philippines (US $6.5 billion/year) and lowest in the Solomon Islands (US $70,000/year). Adaptation is estimated to reduce damage costs significantly, in particular for the Philippines, Indonesia, and Malaysia (between 68 and 99%). These results suggest that the impacts of sea-level rise are likely to be widespread in the region and adaptation measures must be broadly applied.     

Spatial-temporal analysis of wetland landscape pattern under the influence of artificial dykes in the Yellow River delta

The influence of anthropogenic activities,especially artificial dykes,on the coastal wetland landscape is now considered as a serious problem to the coastal ecosystem.It is important and necessary to analyze changes of coastal landscape pattern under the influence of artificial dykes for the protection and management of coastal wetland.Our study aimed to reveal the quantitative characteristics of the coastal wetland landscape and its spatial-temporal dynamics under the influence of artificial dykes in the Yellow River delta(YRD).It was analyzed by the methods of the statistical analysis of landscape structure,five selected landscape indices and the changes of spatial centroids of three typical wetland types,including reed marshes,tidal fiats and aquaculture-salt fields.The results showed that:(1)Reduction of wetland area,especially the degradation of natural wetlands,had been the principal problem since the dykes were constructed in the YRD.The dykes created conditions for the development of artificial wetlands.However,the new born artificial wetlands were still less than the vanished natural wetlands.(2)Compared with the open area,the building of artificial dykes significantly speeded up the changes of landscape patterns and the aggravation of the landscape fragmentation in the closed area.(3)The changes of area-weighted centroids of three typical wetland landscapes were greatly affected by dykes,and the movement of the centroid of the aquaculture-salt field was very sensitive to the dykes constructed in the corresponding period.     

我国中西部生态脆弱带坡耕地水土流失及坡地梯化

中西部生态脆弱带是我国坡耕地集中分布地区 ,坡耕地水土流失是中西部生态脆弱带水土流失的主要类型 ,坡地梯化是防治坡耕地水土流失和实现坡耕地可持续利用的重要措施 ,国家应加大投资力度开展以坡地梯化为中心的坡耕地综合开发整治工作     

Environmental characteristics and land-use pattern changes of the Old Huanghe River delta,eastern China,in the sixteenth to twentieth centuries

The interaction between human and land in estuarine–coastal areas has become a focus of the global change research. Since the sixteenth century, the Old Huanghe River delta has experienced rapid accretion, the formation of rich ecological resources and diverse land use pattern changes; such information, in combination with a large number of historical documents, provides a unique research area for revealing the processes for ecosystem–human changes. We use historical documents and adopt multidisciplinary methods, to identify the relationship between ecosystem changes and human activities, on the basis of spatial and temporal analysis, for in the Old Huanghe River delta region. The results indicate that, in the sixteenth to nineteenth centuries, the long-term monopolistic development pattern under the government leadership, which occupied large quantities of ecological resources, controlled the coastal salt industry and marsh land exploitation. However, along with the delta ecosystem change and population growth, the development pattern became gradually unsustainable, i.e., the salt industry migrated toward the north, while the farming activities migrated toward the south with enhanced intensity of marsh reclamation. The government monopoly collapsed in the late nineteenth century, which enlarged the independent development space for the local residents, which, to a large extent, improved the land-use efficiency and reduced the population pressure.     

近15年来长江源区土地利用变化及其生态环境效应

长江源区是我国重要的水源涵养区,也是高海拔地区生物多样性最集中的地区和生态变化最为敏感的地区。基于1986年TM和2000年ETM+卫星遥感数据和野外实地调查,采用GIS软件和景观生态空间分布格局分析方法,对长江源区近15年来土地利用类型的时空变化进行了研究。结果表明：1986～2000年,源区林地和湿地面积减少54.2 %和42.69 %,建设用地、耕地和未利用土地面积分别增加120 %、43.83 %和21.1 %。全区土地利用的空间位置转换面积大于其数量变化,土地利用类型总变化的面积大小依次是草地＞未利用土地＞湿地＞水域＞林地＞耕地＞建设用地。土地利用动态转化过程以草地转化为未利用土地、湿地转化为草地和未利用地逆转为草地为主要特征。15年里景观破碎化程度加剧,分维数和多样性指数增加,优势度降低,景观异质性增强。长江源区脆弱的生态体系对土地利用变化响应强烈,造成水土流失与沙漠化程度加剧,导致大范围高寒草甸、草原植被退化,湿地萎缩。气候变化和人类经济活动是导致研究区土地利用变化的主要因素。     

Analyzing coastal wetland change in the Yancheng National Nature Reserve,China

Coastal zones provide habitat cores and corridors that maintain the diversity of entire landscapes, and they can form the cornerstone elements of regional conservation strategies. Natural environmental driving factors and excessive anthropogenic activities play important roles in coastal wetland change. Many studies have used remote sensing images to map and assess coastal wetland change on local or regional scales. This paper aims to provide insight into coastal wetland change in the Yancheng National Nature Reserve (YNNR) using remote sensing technology and landscape metrics analysis. The results reveal that grass flat and reed areas have significantly decreased, whereas agriculture fields, aquaculture ponds and built-up areas have continuously increased from 1988 to 2006. The spatial pattern of the coastal landscape has become fragmented and heterogeneous under great pressure from rapid economic development and population growth. The wetland changes have important impacts on natural habitat of the red-crowned cranes. The results of this study provide basic information that is required for developing measures toward a sustainable management and conservation of the YNNR.     

基于CLUE-S模型的湿地公园情景规划——以南京长江新济洲国家湿地公园为例

基于计算机模型的湿地公园规划具有低成本、高效率、多情景等优点,可以为规划研究提供初步方案的评优和选择。将CLUE-S模型运用到湿地公园规划中,结合生态保护情景和旅游开发情景的设定,对新济洲湿地公园进行2020年景观格局模拟预测,最后从湿地鸟类穿越的最小累积阻力模型角度,对两种情景进行了比较分析,得出如下结论:(1)对CLUE-S模型在研究区的适用性进行验证,经过计算,模拟的精度检验指数Kappa值为0.763,表明CLUE-S模型用来做新济洲湿地公园景观格局变化的预测模型具有良好的可靠性;(2)土壤有机质含量是推动新济洲湿地公园景观变化的最重要驱动因子,其影响力度远远高于其他因子;(3)通过建立MCR模型可以发现,两种情景都具有各自的优缺点,对于生态保护情景需要注意的是拓宽湿地鸟类穿越廊道,减少最小累积阻力路线生态缓冲区内的人为干扰。而对于旅游开发情景来说,构建整体的生态串联性则显得尤为重要,需要在中部大阻力区域为湿地鸟类穿越开辟一条良好的保护通道。     

升金湖湿地时空演变对越冬鹤类种群动态的影响

升金湖湿地是我国主要的鹤类越冬栖息地之一。研究升金湖湿地时空变化对越冬鹤类种群动态的影响在湿地生态环境改善、鹤类种群恢复等方面具有重要参考价值。对1986～2015年升金湖湿地白头鹤（Grus monacha）、白鹤（Grus leucogeranus）、灰鹤（Grus grus）及白枕鹤（Grus vipio）种群数量的变化趋势分别进行了曲线拟合；结合升金湖湿地1986~2015年间8期遥感影像分析了研究区土地利用/覆盖的时空变化；并探讨了湿地时空变化与越冬鹤类种群数量变化之间的相关性。结果表明：1986~2015年间，研究区的景观格局发生了较大变化，草地、水田、滩涂及其他用地的面积总体呈增加态势，而林地、旱地、水域及芦苇沼泽地面积总体呈减少的态势；4种鹤类的数量总体呈下降趋势，曲线拟合中白鹤和白枕鹤种群数量变化的趋势方程拟合度较高；芦苇沼泽地及水域面积变化与越冬鹤类种群数量呈显著的正相关关系，而草地、滩涂及水田的面积与鹤类种群数量呈较强的负相关关系；其他景观面积变化间接对鹤类种群数量产生影响。 关键词： 时空变化；鹤类；遥感影像；土地利用/覆盖；升金湖     

流域土地利用变化的长周期水文效应及管理策略

长周期水文效应作为不同强度暴雨事件的综合反映，对流域规划和管理决策非常重要。以太湖地区蠡河流域为研究区，通过解译1984年、1995年和2000年3个时段TM/ETM获得土地利用分布地图，分析其土地利用变化的模式，并基于研究区30年的降水序列，应用长周期水文分析模型L-THIA（Long-Term Hydrologic Impact Assessment），计算3个时段土地利用特征对暴雨地表径流的影响，分析不同土地利用类型水文效应的敏感性，在此基础上总结了减少流域水文效应的土地利用管理策略。分析结果显示，该区土地利用有明显变化，主要表现为水田、旱田向建筑用地的转化，从1984年到2002年，城镇及居民地扩展占流域总面积的4.199 4 ％，地表径流量增加了6.170 ％，不同土地利用方式的水文效应有较大差别，林地、湖滩湿地的敏感性最大，其次是水田和旱田。     

厦门海岸带湿地变化的研究

通过“压力-状态-响应”分析模型，对厦门海岸带湿地变化的主要原因（压力）、成分退化和结构改变（状态）以及对厦门海岸带生态系统的主要影响（响应力）之间的作用机制进行了探讨。提出厦门海岸带湿地面临的主要压力来自海岸带围垦造地、近海滩涂养殖和九龙江河口输入；状态变化突出表现在浅海海域面积的减少。红树林的面积减少。近岸泥沙淤积。沉积物类型改变和沉积物污染；主要影响是造成厦门海域水质下降、近海底橙生物类型改变、航道泥沙淤积、水产养殖产量下降和珍稀海洋物种分布和数量改变。     

基于重力空间熵的城市湿地压力模型构建研究——以武汉南湖湿地为例

城市化进程中人口和建设用地需求增加引发的湿地退化压力日益凸显，熵理论为城市扩张、土地利用结构变化和城市湿地退化压力建模研究提供了新思路。已有研究表明，城市湿地损失、湿地区域建设用地的增加会导致土地利用结构空间熵的数值不断下降，但仅依靠空间熵理论难以定量湿地退化压力。因此依据城市地理学中的重力递减理论，引入距离因素，从湿地区域土地利用空间熵、湿地本身面积、距湿地中心的距离、距商业中心的距离4个要素构建重力空间熵的城市湿地压力模型。研究以1988年武汉南湖湿地遥感影像为基础，制作矢量图，从南湖湿地周边众多湖泊湿地中，随机选取40个样本湿地，分别计算了1988年、1992年、1996年、2000年、2004年5个时期的样本湿地压力值，并利用Kriging空间插值对南湖湿地所受的压力值分布进行可视化处理。结果表明：（1）湿地所在区域土地利用空间熵越小，湿地所承受压力越大；距中心湿地越远越靠近城市商业中心且面积越小的城市湿地更容易发生消亡；（2）根据城市湿地压力模型计算的压力值大的湿地更容易在下一阶段发生显著的损失或消亡；（3）随着城市化的推进，建设用地的扩张，城市湿地承受的压力值逐年增加，当压力值到达0.7左右，湿地存在极大消亡风险。遥感影像解译的结果与按照重力空间熵的城市湿地压力模型计算结果一致，说明该模型能较好地预测城市湿地在城市扩张压力下的演化过程。模型的建成对于城市湿地动态变化和保护规划具有重要意义，了解并把握这一湿地损失过程和趋势，预测城市湿地在城市扩张压力下的演化过程能为城市管理者对城市湿地的具体保护提供方向和指导。 关键词： 城市湿地； 重力空间熵； 压力模型； 城市扩张划具有重要意义，了解并把握这一湿地损失过程和趋势，预测城市湿地在城市扩张压力下的演化过程能为城市管理者对城市湿地的具体保护提供方向和指导。 关键词： 城市湿地； 重力空间熵； 压力模型； 城市扩张     

江苏沿海滩涂地区农户经济行为研究

江苏海岸带是中国最重要的海岸带湿地之一。滩涂资源的可持续利用成为当前研究的焦点。农户是滩涂开发的微观经济活动的主体和相对独立的生产单位。农户的经济行为对滩涂开发和利用产生直接和重要的影响。以江苏省盐城市的射阳县、大丰市为例，选择3个典型村庄进行入户访谈式调查．在对220个农户进行了入户随机抽样调查的基础上，利用区域经济动力学原理Logisti模型和Cobb-Douglas生产函数。建立了农户经济行为对环境影响的数量经济模型。研究表明，滩涂区农户经济行为对滩涂环境压力的大小及类型具有直接影响。土地经营规模、土地利用类型、生产投入、投资意向、农户受教育水平等是产生影响的主要因素。找出滩涂资源利用中存在的问题和主要的环境压力在于：农户经济生产方式单一，产业结构不合理；农户教育水平较低，环境意识差；滩涂利用经济效率低．环境压力大；农户抗市场风险能力差。并提出了相应的对策和建议。     

An integrative approach to modeling land-use changes: multiple facets of agriculture in the Upper Yangtze basin

Land change science has emerged as a fundamental component of global environmental change and sustainability research. Still, much remains to be learned before scientists can fully assess future roles of land-use/cover changes (LUCC) in the functioning of the Earth system and identifying conditions for sustainable land use. The objective of this paper is to gain a better understanding of the complex interactions of human and natural drivers underlying LUCC. We do so by developing and estimating a novel structural model of land use and using spatially explicit longitudinal observations from the Upper Yangtze basin of China. Our analysis focuses on the multiple dimensions of agriculture—not only cropland use itself, but also grain production, soil erosion, and related technical change—and our data cover 31 counties over four time periods from 1975 to 2000. Our results show that technical change plays an important role in supplying food on a limited cropland; limiting cropland expansion in turn reduces soil erosion, which then benefits grain production in the longer term. It is also found that policies and institutions have significant impacts on land use and the status of soil erosion. Together, these results carry some great implications to sustainable land use and ecosystem management.     

Monitoring a Recent Delta Formation in a Tropical Coastal Wetland Using Remote Sensing and GIS. Case Study: Guapo River Delta, Laguna de Tacarigua, Venezuela

The integrated use of remotely sensed data and GIS to monitor a rapid recent delta formation was undertaken in the Tacarigua Lagoon, a mangrove coastal protected wetland in the north-central coast of Venezuela. Recently, the resource value of coastal wetlands such as coastal lagoons and deltas, has brought about a need to protect and conserve these ecosystems. To that end, valuable resources such as these should be continuously monitored so that temporal changes in their environment can be analysed. The importance of determining the cause, extent, and spatial distribution of these changes can then be used in different aspects of environmental studies, land suitability analyses and for wise resource management. Aerospace data interpretation and a field survey were utilised to study the formation of the Guapo River delta within the Tacarigua Lagoon and to map the expansion that this depositional environment has undergone. A historical set of aerial photographs and a radar image, together with a GIS, were used to assess the growth of the delta from the beginning of its formation up to the present time.     

景区依托型乡村聚落用地格局与功能演变研究——以黄果树镇石头寨村为例

以毗邻黄果树瀑布风景区旅游村落石头寨村为典型案例,运用空间分析和参与式评估方法,利用聚落用地现状与多时相遥感影像数据,分析了34年来石头寨村聚落用地格局的变化规律。研究发现:(1)石头寨村聚落用地格局演变经历了缓慢起步、加速扩张及扩张回落3个阶段;土地利用实现了从村落中心区到外围区,从平面到立体的空间拓展过程;空间上呈现较为显著的沿河、沿路扩张模式;(2)"旅游化过程"促使石头寨村乡村聚落用地功能的转变,乡村单一的村民居住型用地比例降低,旅游住宿、旅游餐饮、旅游服务等非居住用地比例上升,乡村聚落功能由单一的居住生活功能向居住—休闲旅游复合功能转变;(3)自然地理条件是乡村聚落空间扩展的基础,旅游资源开发是乡村用地扩展的支撑动力,黄果树瀑布景区旅游市场需求快速增长是乡村功能转化的重要推动力,政府调控是乡村用地变化的引导动力,这些因素相互作用,共同驱动景区依托乡村聚落用地格局的变化。当前石头寨村进入以特色旅游发展为导向的转型升级阶段。对其乡村旅游发展而言,原有用地模式具有不可持续性。因此,要促进乡村旅游可持续发展,必须针对旅游型乡村聚落用地特点和要求,充分考虑现有乡村聚落旅游用地需求,加强乡村用地规划设计和建设管理,并完善相配套的制度体系。     

土壤侵蚀对土地利用和降雨变化响应和空间分布特征——以金沙江一级支流小江流域为例

全球变化引起了一系列环境效应，土壤侵蚀是全球变化最为敏感环境效应之一。选择生态极其脆弱区小江流域作为研究对象，通过遥感影像和雨量站点获取3期土地利用和降雨变化信息，结合区域基础地理信息数据，利用通用土壤流失方程（USLE模型）对该区域土壤侵蚀对土地利用和降雨变化的响应进行了分析。研究表明：（1）降雨量在1981~1990年为降雨量较小年份，1991~2000年为降雨量较大时间段，2001~2005年降雨量开始急剧减少；（2）1987、1995和2005年的平均侵蚀量分别为：7058、8008和7981 t/（hm2〖DK1〗·a)，中度侵蚀以上面积分别占总面积的2992%、3383%和3318%，其中极强度侵蚀分别占915%、1281%和1263%；（3）在分布特征上，强度侵蚀和极强度侵蚀主要分布在小江流域的中下游地段。极强度侵蚀主要分布在中海拔区域（1 600~2 800 m），所占的比例呈持续下降的趋势，但在高海拔区域，极强度侵蚀呈增加趋势；同时，极强度侵蚀集中分布在高坡度段（>35°）上，占其面积的85%以上，且呈持续增加趋势，在中坡度段（15°~35°）上，极强度侵蚀呈现明显的减少趋势。USLE模型可以较好的反映出全球变化条件下土壤侵蚀效应，为合理开发土地资源和人类经济活动提供科学依据     

Land-use portfolios and the management of private landholdings in south-central Indiana

In the study of land-use and land-cover change as an important contributor to regional environmental change, linking household level land-use decisions to particular land-cover patterns has been an enduring challenge. The frequent conflation of land use and land cover has been appropriate and fruitful in regions where extractive activities are common, but the decoupling of household characteristics from land-cover choices in exurban landscapes may require that the two be treated separately. This research employs the concept of a land-use portfolio, defined as a unique combination of land use types, and land cover derived from remote sensing to examine the relationship between land use and land cover at the parcel scale. Data on the type and spatial organization of land use were collected for individual parcels through sketch maps constructed by land owners and then described quantitatively using GIS and spatial metrics from landscape ecology. The results of this analysis suggest that in the naturally forested region of south-central Indiana, parcels are frequently managed as multiple types of land use thereby supporting the portfolio approach. Generally, land-management complexity is related to land-cover fragmentation, but the strength of this relationship varies across portfolio types. In addition, substantial amounts of forest land cover occur in non-forest land uses further supporting the need to treat the two separately to accurately link land use intentions and land cover outcomes.     

Exposure of atoll population to coastal erosion and flooding: a South Tarawa assessment, Kiribati

Atoll countries are particularly vulnerable to coastal hazards in the context of global change, which justifies the interest in population exposure assessments. This paper contributes to addressing this need by assessing the current exposure of the population of two areas of the South Tarawa Urban District (Tarawa Atoll, Republic of Kiribati) to coastal erosion and flooding. The assessment is based on data relating to island morphology (digital terrain models and shoreline change), land use (building extension and coastal works) and environmental changes reconstructed for the 1969–2008 period. The results highlight rapid changes in land use and significant differences in current population exposure to coastal erosion and flooding between and within study sites. Between 1969 and 2007–2008, the built area located less than 20 m from the reference shoreline has increased by a factor of 4.2 at Bairiki and by a factor of 32.2 at Eita–Bangantebure, enhancing population exposure given that land elevation is low (12.6 and 77.4 % <2 m at Bairiki and Eita–Bangantebure, respectively). Nevertheless, in Bairiki, 87.5 % of the built area is currently not exposed to coastal erosion (>20 m from the coastline) and flooding (>1.5 m). Building exposure is higher at Eita–Bangantebure, where 71.3 % of the built area is currently not exposed (using the same criteria), but 17.1 % shows medium to very high levels of exposure, due to very low land elevation (22.3 % of the land area <1.5 m) and shoreline recession. The Eita–Bangantebure case study exemplifies the maladaptive trajectories of change that have been reported in other atoll countries.