近25年三峡库区土地覆被变化及驱动力分析

基于1990、2000、2005、2010和2015年五期30 m空间分辨率土地覆被遥感数据，利用动态度模型和转移矩阵，综合分析了近25 a三峡库区土地覆被的时空格局、变化特征及驱动力。研究结果表明：2015年三峡库区土地覆被以森林和耕地为主，分别占总面积的41.45%和24.58%；1990~2015年三峡库区人工表面、湿地、森林和其他用地的面积增长明显，耕地、灌丛和草地的面积整体减少，区域综合土地覆被动态度呈先增加后稳定的变化趋势，人工表面是最为活跃的土地覆被类型，其次是湿地和耕地；前10 a三峡库区人工表面占用耕地较为突出，后15 a土地覆被类型转换主要为森林、灌丛和耕地转为人工表面和湿地；三峡工程建设、移民安置与迁建、经济发展与城镇化导致人工表面不断扩张，水库蓄水导致湿地面积迅速增加，农业结构调整促使园地面积扩张。三峡库区近25 a来，在退耕还林等生态保护政策影响下，生态环境状况趋于改善，库区森林面积显著增加，坡耕地面积持续减少，但人地矛盾日益突出，研究结果可为后三峡时代库区生态环境保护与社会经济的协调发展提供数据支撑。     

四川马边彝族自治县土地利用/覆被变化分析

采用基于最大似然法的监督分类方法对四川省马边彝族自治县1988年和2001年两期Landsate5 TM影像进行解译,利用单项土地利用动态指数〖WTBX〗（LUDI）、双向土地利用动态指数（Ki）以及土地利用类型转移矩阵（Cx×y）〖WTBZ〗等定量分析方法分析解译结果,得到马边县13年间土地利用/覆被动态及转移特征,并对可能的生态影响进行了分析预测。结果显示：①次生林面积增加,针叶林面积有所下降,灌草地被农田大量取代;②城镇及居民点和次生林的动态最为活跃,转入面积明显高于转出面积;③中山区和亚高山区林地构成发生变化,高山草甸面积有所萎缩,河谷区的阔叶林带被次生林大量取代,低山河谷区的土地破碎化程度增加。研究表明,13年间马边土地利用/覆被变化具有动态高、转换活跃、空间性强以及人为活动干扰影响明显等特点。其中,低山丘陵区的灌草坡大量被农地替代、中山区和亚高山区次生林面积扩大应该作为生态退化的信号加以重视。另外,气候变化对马边森林植被演替可能产生的影响应在今后进行深入的分析研究     

川滇农牧交错区地形特征对土地利用空间格局的影响

川滇农牧交错区位于我国青藏高原的东南缘，地形地貌特征复杂，研究该区土地利用特征与地形之间的关系，有助于了解人类开发活动与自然地理条件之间的关系，对区域的资源开发和生态保护具有重要的现实意义。基于RS＼GIS技术，采用遥感调查、土地利用结构分析和GIS空间分析方法，研究了该区 1988～2000年的土地利用特征，以及不同土地利用类型的空间分布与地形因子之间的关系。初步结果发现：耕地、林地和草地是研究区内受人类活动影响的主要土地类型，也是类型转换相对频繁的土地类型；地形因子对不同土地利用类型的空间分布具有显著影响，其中，海拔在垂直方向上对土地利用空间布局具有控制性作用。研究结果同时表明，地形特征是川滇农牧交错区土地利用空间格局形成的基础，其原因在于地形因子通过影响水热条件及其他自然资源要素在本区内的再分配，进而影响着人类对土地资源的利用方式和利用程度.     

Land Cover Changes Between 1968 and 2003 In Cai Nuoc,Ca Mau Peninsula,Vietnam

Since 2000, the shrimp industry expands at a fast rate in the coastal areas of the Mekong Delta, Vietnam. Shrimp farming is known for its negative impact on the coastal environment. However, other human interventions like agriculture and urbanization also deteriorate the coastal environment. The land cover changes between 1968 and 2003 were determined and analyzed for the Cai Nuoc district, Ca Mau Province, Vietnam, using photos from 1968, 1992 (aerial photographs), 1997/98 (Spot) and 2003 (Landsat). It was clear that the district underwent serious land cover changes: deforestation between 1968 and 1992, with a simultaneous increase in rice land; a rapid decline in rice acreage from 1997 onwards, and, simultaneously, a blitz-increase in shrimp farming area. The forest area declined by 75% between 1968 and 2003. About 40% of this loss could be attributed to shrimp farming, while the remaining 60% was attributed to needs for agricultural land. Still, at present, shrimp farming is the major source of mangrove loss in the district. In 1999 shrimp farms covered 6.374 ha, in 2000 they covered 61.049 ha of the Cai Nuoc area. The swap from rice cultivation to shrimp farming was most-probably driven by households’ hopes for a higher income. It must be feared that the shrimp industry will have a negative impact on the environment (e.g. salinization) and on the livelihood of the district’s households. In 1968 saline water covered 219.9 km², in 1992, 1997/98 and 2003 the saline surface water area covered 92.4, 135.2 and 835.0 km², respectively. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Forest protection and economic development by offshoring wood extraction: Bhutan’s clean development path

With globalization, virtual exchanges of natural resources embodied in traded commodities redistribute geographically land use and its environmental impacts. Benefits of national forest protection may be undermined at the global-scale by leakage through international trade. We studied land use displacement associated with national policies to protect forests in Bhutan. This case study provides a simple situation: a dominant forest cover almost unaffected by agricultural expansion, a rural economy dominated by the primary sector, centralized forest conservation policies, and a dominant trading partner. We assessed the net effects at the international level of the Bhutanese forest protection policies by accounting for trade in wood products with India. Our results show that these policies have been effective in maintaining a high forest cover, but have been accompanied by an increasing displacement of forest use to India. In 1996–2011, the difference between the total volume of wood imported from India and the total volume exported from Bhutan—i.e., the net displacement—corresponds to 27 % of the total volume consumed in Bhutan. In 2011, 68 % of the total forest area required to produce the wood consumed in Bhutan was located in India. The wood imported by Bhutan was likely originating from tree plantations in the northeastern Indian states. Since Bhutan has few tree plantations and very valuable natural forests, the net international-level ecological impacts of this land use displacement is arguably positive. Most of the wood imports of Bhutan were wood charcoal for its emerging chemical industries. This case of displacement reflects functional upgrading in the value-chain rather than an externalization of consumption-based environmental costs. Through its government policies, Bhutan has managed to support its economic development while protecting its forests and leapfrogging the negative impacts on forests generally associated with the early stages of modernization.     

The livelihood potential of non-wood forest products: The case of Mbooni Division in Makueni District, Kenya

Forestry is a productive sector with significant effects on meeting national socio-economic and environmental functions as well as the improvement of rural livelihoods. Non-wood forest products (NWFPs) in particular have been widely advocated by conservation and development organisations as potential alternative livelihood strategies, particularly among vulnerable forest dependant households. Like in most tropical countries, NWFPs are relevant in the sustainable development of Kenya that is particularly endowed with important forest resources. Kenya hosts about 17 million ha of forested land (about 3.51% of the total Sub-Saharan Africa forest cover by 2000), of which about 16,865,000 ha is under natural forest (EarthTrends: Forests, grasslands and drylands, 2003). Outside the gazetted forests, there are other large tracks of forests in trust lands, including national parks and reserves, hill forest reserves and privately owned lands covering about 0.5 million ha (Kenya’s forest resource assessment in the EC-FAO Partnership Programme Report, 2000; The Kenya Forests Act, 2005). Woodlands, bushlands and wooded grasslands, mainly found in the arid and semi-arid lands cover 37.6 million ha, while forest plantations (started in 1946) cover about 170,000 ha of land (The Kenya forestry master plan, 1994–2020, 1994). In most NWFPs endowed regions of the country however, this socio-economic and environmental potential is still unrealized. We illustrate the latter by a case study of NWFPs use and management in four villages in Mbooni Division of Makueni District, Kenya. The division was chosen because of its relatively high NWFPs availability, particularly from South Mbooni forest that is located at a distance less than 5 km for an estimated 80% of the interviewed households. Data used for the analysis was collected through a fieldwork survey carried out on women (35+ years) in August, 2005. One hundred and sixty (160) NWFPs are harvested (from plant and animal species) and used mainly for food, income generation (supplemental) and medicinal purposes. A number of challenges limit women’s enjoyment of the full benefits from NWFPs exploitation, the overriding problem being their inadequacy (in quantity and/or quality). In this paper we discuss these commonly utilized and managed NWFPs plant species in Mbooni and their potential contribution to improved livelihoods and sustainable development in Mbooni, Kenya and Sub-Saharan Africa (SSA) in general.     

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。     

基于面向对象的石漠化山区植被信息提取及分布特征研究

重庆东北部地区是重庆岩溶石漠化重点治理区，该区地形复杂，山高坡陡，植被退化现象严重。了解该地区的植被分布特征，对该区环境的改善和石漠化治理具有十分重要的现实意义。基于Landsat OLI等数据，运用面向对象分类方法对研究区植被信息进行提取，然后对分类后的数据进行统计、制图和分析，并在空间布局上进行总结和探讨，旨在了解该区域植被的空间分布特征和规律。结果表明：（1）在eCognition 9.0软件中进行多尺度分割，再结合地物类型特征使用隶属度函数法进行分类，该方法符合山地地物类型的分布规律和特点，分类精度达到81.35%；（2）研究区属典型的中山地区，海拔在500~1 500 m之间的地区约占64.49%，林地和耕地是该区域主要的地物类型，所占总面积为8 872.22 km2，占研究区总面积的96.50%，各地物类型分布受地形地势的影响较大；（3）综合研究区地形因子(高程和坡度)与植被分布的相关性可知，耕地和草灌主要分布在高程为200~1 500 m且坡度等级在2~4级（5°~35°）之间，该区域人类活动频繁，故受人类活动影响较大，植被覆盖度低，群落生长不稳定，容易受到干扰。针阔混交林主要分布在高程>500 m且坡度等级在2~4级（5°~35°）之间。马尾松林、阔叶林和柏木林主要分布在高程大于500 m且坡度等级在2~5级（5°~45°）之间。 关键词： 多尺度分割；面向对象分类；地形因子；植被空间分布     

Modelling land use change across elevation gradients in district Swat, Pakistan

District Swat is part of the high mountain Hindu-Kush Himalayan region of Pakistan. Documentation and analysis of land use change in this region is challenging due to very disparate accounts of the state of forest resources and limited accessible data. Such analysis is, however, important due to concerns over the degradation of forest land leading to deterioration of the protection of water catchments and exposure of highly erodible soils. Furthermore, the area is identified as hotspot for biodiversity loss. The aim of this paper is to identify geophysical and geographical factors related to land use change and model how these relationships vary across the district. For three selected zones across the elevation gradient of the district, we analyse land use change by studying land use maps for the years 1968, 1990 and 2007. In the high-altitude zone, the forest area decreased by 30.5 %, a third of which was caused by agricultural expansion. In the mid-elevation zone, agriculture expanded by 70.3 % and forests decreased by 49.7 %. In the lower altitudes, agriculture expansion was 129.9 % consuming 31.7 % of the forest area over the forty-year time period. Annual deforestation rates observed were 0.80, 1.28 and 1.86 % in high, mid and low altitudes, respectively. In the high-altitude ecosystems, accessibility (distance to nearest road and city) had no significant role in agriculture expansion; rather land use change appears significantly related to geophysical factors such as slope, aspect and altitude. In the low-elevation zone, accessibility was the factor showing the closest association with agriculture expansion and abandonment. The analysis illustrates that land use change processes vary quite considerably between different altitudinal and vegetation cover zones of the same district and that environmental constraints and stage of economic development provide important contextual information.     

杭州湾南岸滨海平原土地利用/覆被空间格局变化分析

杭州湾南岸滨海平原位于沪、杭、甬经济金三角的中心地带,是我国沿海经济最发达的地区之一。研究其土地利用/覆被空间格局变化对合理利用土地资源,促进沿海地区的可持续发展具有重要意义。利用1987年和2000年2个时期的TM影像,分析了杭州湾南岸滨海平原土地利用/覆被数量及空间格局变化特征。结果表明,杭州湾南岸滨海平原建设用地、水体和养殖用地呈现明显的增长趋势,水田、旱地、滩地、林地和盐田呈减少趋势。受自然和人类活动的共同影响,土地利用/覆被类型斑块平均面积由0.245 km2降至0.173 km2,斑块密度则由4.081个/km2提高到5.781个/km2,斑块数量增加了42%。由于斑块的破碎化,大部分土地利用/覆被类型的边界密度、形态指数、分维数和斑块密度都有不同程度的增加。城市化和非农化的发展使得建设用地格局指数变化表现出一定的特殊性。     

最近10年鄱阳湖区土地利用格局的时空变化

利用1988和1998年4月份的TM遥感数据,采用最大似然法对翻阳湖区的土地利用进行机助分类。把研究区土地利用分成7种类型：林地、灌草坡、水体、湖滩洲地、耕地、城镇用地和裸地。采用空间叠加的方法得到研究区土地利用的转移短阵。结果显示,林地、水体、城镇的面积增加,灌草坡的面积减少。1998年耕地面积比1988年面积减少11．3％,湖滩洲地面积减少42．7％。对不同高程的土地利用变化分析表明,耕地、灌草坡的面积都有所减少;城镇的面积增加,林地的面积增加明显,尤其在丘陵山区。土地利用的变化受到自然和人文因子的双重影响。水体面积增加的主要因于是降水量的增大;林地、灌草坡的变化明显受到政策等因素的影响,湖滩洲地减少的主要原因是水位的升高。     

Forest land conversion dynamics: a case of Pakistan

The present research focuses on estimating forest area change with respect to the ongoing forest land conversion. The study tests the hypothesis that forest land is being converted to the selected land use categories with high growth tendency and controlling deforestation rate to its half of the present level would significantly improve the land cover under forest. The rate of forest land conversion to other land use categories is analyzed and then compared with the total area expanded under three land use classes. We used Systems dynamic modeling approach to estimate forest area by simulating forest land conversion in Pakistan, projecting to 2030. The results show that rangeland, built-up area and cultivated land have increased over time; growth rate of built-up area (9%) is highest followed by rangeland area (1.7%) and cultivated area (0.3%), respectively; rangeland is the dominant category in terms of area expanded (0.74 m. ha). Sensitivity analysis showed that reducing deforestation rate to half of the past level of 1% could not significantly improve forest area; therefore, it is suggested that controlling deforestation alone is not an effective strategy unless drastic measures, e.g., demarcation of forest boundaries, land use control policy and afforestation campaign would be started in the country.     

Land changes and their driving forces in the Southeastern United States

The ecoregions of the Middle Atlantic Coastal Plain, Southeastern Plains, Piedmont, and Blue Ridge provide a continuum of land cover from the Atlantic Ocean to the highest mountains in the East. From 1973 to 2000, each ecoregion had a unique mosaic of land covers and land cover changes. The forests of the Blue Ridge Mountains provided amenity lands. The Piedmont forested area declined, while the developed area increased. The Southeastern Plains became a commercial forest region, and most agricultural lands that changed became forested. Forests in the Middle Atlantic Coastal Plain declined, and development related to recreation and retirement increased. The most important drivers of land conversion were associated with commercial forestry, competition between forest and agriculture, and economic and population growth. These and other drivers were modified by each ecoregion’s unique suitability and land use legacies with the result that the same drivers often produced different land changes in different ecoregions.     

城市湖泊地区的土地利用变化--以武汉东湖为例

利用1986、1993、1999年的Landsat TM卫星遥感影像和1981年地形图,借助GIS技术分析了城市湖泊地区—武汉东湖流域1987～1999间土地利用的时空变化及景观结构的变化。土地利用分为水体、针叶林、阔叶林、灌草、裸地、农业用地和城镇用地七种类型。各时期遥感影像分类精度都在85%以上。该流域土地利用变化以城镇大幅度扩展（从占全流域面积的9.1％到29.6％）、农业用地增加(从7.0％到13.9％)和由此引起的林地（从占全流域面积的33.6％到24.3％）、水体（从30.4％到23.8％）面积减少为主要特征。同时流域整体的景观多样性下降、优势度提高,但不同景观组分的碎裂化程度的变化趋势不同。其中,城镇用地等优势景观组分的分布趋于聚集,其他类型多趋于碎裂化。流域的城市化具有方向性。城市的快速扩展对林地、灌草、水体等城市湖泊地区的自然生态系统产生显著影响。流域的土地利用及变化受多种自然、社会因素影响。     

Examination of land use/land cover changes,urban growth dynamics,and environmental sustainability in Chittagong city,Bangladesh

As in many other developing countries, cities in Bangladesh have witnessed rapid urbanization, resulting in increasing amounts of land being taken over and therefore land cover changing at a faster rate. Until now, however, few efforts have been made to document the impact of land use and land cover changes on the climate, environment, and ecosystem of the country because of a lack of geospatial data and time-series information. By using open source Landsat data integrated with GIS technologies and other ancillary data, this study attempts to classify land use and create land cover maps, enabling post-classification change detection analysis. By this method, we document the spatial and temporal trajectory of urban expansion in Chittagong, the second largest city in Bangladesh, over a 36-year period. The findings suggest that, over the study period, 56 % of the land cover has undergone change, mainly because of the expansion of built-up areas and other human activities. During the 36-year period, the built-up area around Chittagong city has expanded by 618 %, with an average annual rate of increase of 17.5 %. As a result of rapid urbanization, the vegetated hills near urban development areas face serious threats of further encroachment and degradation, given that 2178 ha of hills have already been intruded over the study period. Because urbanization processes in Bangladesh have traditionally been viewed as the result of population growth and economic development, very little work has been done to track the potential growth trajectory in a physical or spatial context. This study, therefore, will contribute to the current understanding of urban development in Bangladesh from a temporal and spatial point of view. Findings will be able to assist planners, stakeholders, and policy makers in appreciating the dynamism of urban growth and therefore will facilitate better planning for the future to minimize environmental impacts.     

Land cover composition determinants in the Uckermark (NE Germany) over a 220-year period

There is broad consensus that land use/cover has changed in central Europe over millennia. However, few studies have addressed the roles of the anthropogenic (socio-economic) and natural (biophysical) factors driving these changes over shorter periods (e.g., 100 years). In this study, we analyse the determinants of land cover composition at three discrete time periods (c. 1780, 1890, and 2000). We hypothesise that different anthropogenic and natural factors are the determinants of the main land cover types (arable fields, grasslands, and forests) and that the effects of natural and anthropogenic factors on the main land cover types differ among landscapes with highly dynamic and more stable forest-open land distributions. The study was carried out in the Uckermark region located in northeastern Germany. We compiled data on natural and anthropogenic factors (e.g. forest cover and number of inhabitants) of 65 municipalities in four landscape sections of equal size (10 × 10 km). Landscape sections were selected to reflect different dynamics (high/low) in conversion from forest to arable fields or grasslands and vice versa from 1780 to 2000. Averaged linear mixed-effect models explained between 7.5 and 81.2 % of the variance. The unique effect of anthropogenic factors varied from 2.1 to 18.7 % and that of natural factors varied from 0.2 to 43.4 %. In four of six models that included both types of factors, the natural factors were more influential than the anthropogenic factors. Except in three cases, anthropogenic and natural factors showed opposite effects on land cover types in more dynamic and more stable windows. Though the Uckermark region has been influenced by human activity for thousands of years, natural factors were a major determinant of land cover composition during all time periods, whereas anthropogenic factors became more important only during the latest time period under investigation.     

南方丘陵地区河谷城市用地时空演变与驱动分析——以上饶市城区为例

以揭示中国南方丘陵地区河谷城市的空间演变过程和特征为目的,以上饶市城区为例,在遥感与GIS技术的支持下,对1988~2013年间上饶市城区城市用地的时空演变过程、特征及驱动影响因素进行了研究。结果表明,1988~2013年的25 a间,上饶市城区城市用地呈现出快速增长的态势,城市形态的演变具有明显的时空特征:时间序列上,不论扩展幅度还是扩展速度,2001~2013年间的值均高于1988~2001年间的值,前后两个时段的扩展特征呈现出明显的差异性;空间格局上,上饶市城区以老城区的中心广场为中心向四周扩展,先后经历了放射性扩展、组团式分散扩展两个阶段,同时呈现出明显的方向分异性,西南和西为其主要扩展方向,而其东南方向的扩展速度最为缓慢。自然环境中的地貌对上饶市城区城市用地的扩展起到很大的限制作用,经济社会的发展、政策规划等因素成为城市用地扩张与时空演化的外在驱动因素。     

Land-cover changes in and around a National Park in a mountain landscape in the Pyrenees

The current state of Mediterranean mountain areas has been driven by two main factors: intense traditional human activity and the dynamics of the ecosystem itself. In this study, we examine land-cover changes in a National Park in the Pyrenees mountains (NE Iberian Peninsula), which was designated a protected area 55 years ago. First, we have analyzed spatio-temporal changes in land-cover pattern and forest dynamics from 1957 to 2005. During this period, land-cover dynamics consisted of two main processes: (i) expansion of the forest area and (ii) increasing cover of forests already present in 1957. To analyze the role of the conservation level of the park, we have also compared the results obtained within the park with those of unprotected, peripheral areas. In the two areas with different protection level, dense forests increased throughout the period because of the reduction in forestry activities. The peripheral area showed a higher rate of forest-cover change from 1957 to 2005 compared to the National Park. This higher increase in forest cover in the peripheral area could be related to a higher proportion in the National Park of screes and rocky areas and to the decline and transformation of forest activities in these peripheral, lower elevation areas.     

Characteristics of deforestation in the Democratic People’s Republic of Korea (North Korea) between the 1980s and 2000s

There has been a significant lack of land cover change studies in relation to deforestation in the Democratic People’s Republic of Korea (North Korea). The purpose of this study is to characterize deforestation in North Korea through land cover change trajectory and spatial analysis. We used three 30-m gridded land cover data sets for North Korea representing the conditions of the late 1980s, 1990s, and 2000s, respectively, as well as a digital elevation model. We examined the land cover trajectories during the two decades, i.e., which land cover became which at the pixel level. In addition, we calculated topographic characteristics of deforested pixels. Major findings from the study are summarized as follows: (1) net forest loss in North Korea was negligible in the latter decade compared to the former (>5000 km²), whereas other land cover changes were still active; (2) as a result of deforestation, forest land cover became mostly agricultural, particularly in the latter decade (95 %); (3) expansion of agricultural land cover continued during the time, increasing by >42 %; and (4) elevation and slope of deforested areas decreased slightly in the latter decade. The key contribution of the study is that it has demonstrated which land cover became which at the 30-m pixel level, complementing existing studies that examined overall forest stock in North Korea.     

The present condition of the Vistula river catchment area and its impact on the Baltic Sea coastal zone

This review paper describes the state of the Vistula basin and the Baltic Sea area. The article is divided into two parts concerning the river and the Baltic coastal zone, respectively. Each part describes the geography and the environmental state of the region and gives an overview of the socio-economic conditions. The environmental state of the study regions is described in terms of annual monitoring data for the main physico-chemical and biological parameters. The data cover the last decade. The socio-economic overview includes parameters such as e.g. population density, industrialization, agricultureand land use.SI: Pirrone