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1.
The extent of tropical deforestation is now being tracked by actors in the nongovernmental, academic, private and government sectors using several different sources of satellite imagery. This paper presents an overview of the satellite systems that can be used for operational forest monitoring in the tropics and examines some recent trends in their use. It also reviews various satellite-based studies to map moist tropical forests and draws upon lessons learned from land cover mapping projects in several countries and regions. The case of Indonesia, examined as a nation undergoing rapid conversion of forest to other land uses, is contrasted with Brazil where satellite-based deforestation monitoring is fully operational. In Indonesia, the paper argues, the creation of a national monitoring system for tropical forest conversion is needed to create a source of transparent, reliable information on forest cover and condition. Such a system is likely to succeed if based on multitemporal, moderate-resolution optical data such as imagery provided by MODIS (Moderate Resolution Imaging Spectrometer). When MODIS images are complemented by radar and fine-resolution imagery from sensors such as IKONOS and QuickBird, areas of abrupt change can be identified and the causes potentially discerned. Thus, satellite imagery at multiple temporal and spatial resolutions can effectively increase transparency in the forestry sector by revealing the rate and extent of deforestation on an annual basis and identifying potential areas of illegal logging.  相似文献   

2.
Abstract:   There has been considerable international progress towards sustainable forest management (SFM) of temperate and boreal forest. However, the effectiveness of SFM legislation in providing for the protection of natural forest values has been largely undemonstrated. In this study, all the SFM Plans in the North Island, New Zealand, approved under the Forests Amendment Act (1993) are assessed. It is concluded that the requirements in the plans for assessing, monitoring and maintaining natural values are inadequate with the lack of public participation, and associated appeal rights over decisions, viewed as the key gap in the legislation.  相似文献   

3.
Remnants of the Waikato: Native forest survival in a production landscape   总被引:1,自引:0,他引:1  
Abstract: This paper addresses the issue of conservation of native biodiversity on privately owned farmland in New Zealand. Based on surveys of Waikato dairy farmers as exemplars of intensive agricultural practice, it examines factors that influence the survival of native forest on land with potential for commercial production. Results suggest that a significant proportion of Waikato dairy farmers regard native forest favourably, although the proportion of farmers who actively conserve their forest is small. Factors that assist the persistence of native forest on dairy farms include personal characteristics of the farmer, past accidents of history which have left forest remnants in place, and physical characteristics of the farm such as topography. While the conservation of native biodiversity within this intensively farmed landscape is strongly influenced by political economy pressures that encourage production, non‐utilitarian motives such as aesthetic enjoyment and family heritage can serve to counter the production ethic.  相似文献   

4.

This study takes a human-geographical approach to examine the crucial problem of deforestation in Madagascar. Current land-use practices on the west coast threaten the survival of the dry primary forest, which exists in a delicate ecological balance under a climate bordering on aridity. A shifting-agriculture system, encouraged by government policy aimed at expanding crop cultivation, is the major factor contributing to the reduction of forested land. The forest is set on fire and the burns used to cultivate maize. After three years, yields drop dramatically, and people search for new areas of forest to clear. The practice is likely to lead to the complete disappearance of the western forests if nothing is done to change the current situation. The main practitioners are migrant Tandroy from the south of Madagascar. They migrate for reasons related to widespread local poverty and cultural practices linked to their reverence for cattle. They destroy the forests less for immediate survival than in order to gain possession of as many zebu as possible, which for them is the only way to acquire social status. Because Androy, their home region, is too poor to permit such acquisitions, migration to and deforestation of the western forest becomes an attractive alternative. The sale of maize to private exporters at a high price provides profits that can be used to buy cattle. This cultivation contributes little to food production in Madagascar, and the Tandroy , motivated by cultural considerations, stand at the base of a chain of exploitation that ends overseas. Agricultural and conservation policies in Madagascar currently do not address cultural and economic complexities such as these.  相似文献   

5.

Describing and explaining land-use change is of critical concern in Madagascar, where land transformations such as deforestation and resulting environmental degradation currently capture widespread attention. While the eastern rain forest recedes in the face of swidden cultivators, the highlands demonstrate more constructive transformations. In this paper I present a case study of land-use change in Leimavo, a small village near Ambositra studied in the 1960s by Jean-Pierre Raison. Here, the twentieth century has seen a gradual reduction in irrigated rice cultivation and cattle husbandry, and a boom in market-oriented orange, vegetable, and grain production. In the long term, a historical landscape of grassy hills has been transformed into a productive cultural landscape with woodlots, anti-erosion benching, rice terraces, fruit groves, and diverse crops. Critical factors determining the trajectory of land-use change include regional population pressure, state policies, market incentives, climate variations, and access to land and water resources. These critical factors, or explanations, are linked in the discussion by the use of a simple heuristic device—the range of choice—as a theoretical framework.  相似文献   

6.
Describing and explaining land-use change is of critical concern in Madagascar, where land transformations such as deforestation and resulting environmental degradation currently capture widespread attention. While the eastern rain forest recedes in the face of swidden cultivators, the highlands demonstrate more constructive transformations. In this paper I present a case study of land-use change in Leimavo, a small village near Ambositra studied in the 1960s by Jean-Pierre Raison. Here, the twentieth century has seen a gradual reduction in irrigated rice cultivation and cattle husbandry, and a boom in market-oriented orange, vegetable, and grain production. In the long term, a historical landscape of grassy hills has been transformed into a productive cultural landscape with woodlots, anti-erosion benching, rice terraces, fruit groves, and diverse crops. Critical factors determining the trajectory of land-use change include regional population pressure, state policies, market incentives, climate variations, and access to land and water resources. These critical factors, or explanations, are linked in the discussion by the use of a simple heuristic device—the range of choice—as a theoretical framework.  相似文献   

7.
Decentralization of governance and natural resource management is an ongoing process in many parts of Africa and Asia. Natural resource management requires spatial land resource data for planning. However, currently the financial and human capacity for natural resource mapping, monitoring and modelling remains low in local governments. In this context, this paper explores how new opportunities provided by the increasing availability of free satellite imagery, digital elevation data and open source spatial analysis software, can be applied by local government and NGOs to conduct sophisticated natural resource mapping and modelling in ways that meet their needs and incorporates local knowledge. Reported are cases of a local government using free geospatial data and GIS software to improve evidence‐based natural resource management in the developing world with a focus on raster data applications for satellite image analysis and terrain modelling. It is argued that, through removing barriers to uptake, such applications provide a means of decentralizing landscape analysis skills to improve local natural resource management. This hypothesis is supported through examples of a local government applying these tools in eastern Indonesia, and within this context barriers to wider adoption are explored.  相似文献   

8.
Road building in Congo Basin forests has increased due to expansion of commercial logging, with potential to expose intact forests to greater establishment of agriculture. We developed new knowledge of agriculture clearing sizes, spatial patterns, and relationships with roads in seven case study sites comprising 7,529 km2. Using very high spatial resolution satellite imagery, we mapped roads and rivers, plus clearings for agriculture, settlements, and logging. Mapped clearings (N = 1,781) ranged in size from 0.008 ha to more than 300 ha; most were smallholder agriculture, with 64 percent ≤ 1 ha. Statistical tests of spatial pattern confirmed that agriculture occurred in an inhomogeneous-aggregated pattern, suggesting interactions with other landscape elements. Proximity analyses showed that 76 percent of clearings were within 1 km of a road or river. Thirty-five percent of agriculture clearings were within 1 km of main public roads built before 1990, compared to 17 percent for logging roads built after 2000. Less than 6 percent of agriculture clearings were within 1 km of logging roads with overgrown canopies, suggesting transient relationships. Results based on fine-scale data provide new empirical support for understanding the interactions between agriculture and roads in one of the remaining relatively intact forest areas of the Congo Basin.  相似文献   

9.
I.IntroductionChangesinwetlandsplayanimportantroleinglobalchange.Moreandmoreatentionisbeingpaidtochangesinwetlandsandtheirimp...  相似文献   

10.
Rapid urbanization has resulted in the loss of coastal and marine habitats in cities worldwide. The effective conservation of urban coastal ecosystems requires detailed knowledge of their spatial distribution, necessitating high-resolution mapping. Our study produces a high-resolution coastal and marine habitat map and shoreline map for the tropical city-state of Singapore created through pixel-based supervised classification of satellite imagery, bathymetry data and expert ground knowledge. These maps can be used as a base reference for multiple applications including ecological research, conservation and urban planning. They also help identifiy trends in the extent of key coastal habitats, providing insight into their differing levels of vulnerability to loss and potential for restoration to ensure long-term resilience. The method used for mapping shoreline typologies and resulting insights gained, can guide other rapidly urbanizing coastal cities on strategies to assemble useful spatial knowledge for effective conservation of their urban coastal ecosystems.  相似文献   

11.
卫星遥感作为一种先进的水环境监测技术手段,可以监测现状,掌握现有情况;也可以追溯过去,揭示变化规律;同时还可以结合动力模型,模拟未来。这为人类了解、掌握和管理流域水环境变化发挥不可替代的作用。特别是近10 a已经进入“高分卫星时代”,卫星传感器的空间分辨率越来越高,可观测的参数越来越多,反演和估算精度越来越高。但是,目前还缺乏从流域角度阐述水环境遥感的相关综述文章。论文围绕“流域水环境遥感”研究主题,明确了研究的对象和范围,厘清了基本理论框架,并结合大家关注的问题,包括卫星数据源、水环境模型、富营养化湖泊藻类富集、水生植被退化、水面积变化等方面的研究进展和存在的问题进行了回顾和梳理;并指出在全球变暖和人类活动加剧背景下,未来需要研发专门面向流域水环境的天-空-地立体观测体系和系统框架,开展全流域统筹的水环境遥感监测和模拟,同时加强流域水体碳循环遥感研究。  相似文献   

12.
基于神经网络模型技术的南京市主城区城市森林遥感调查   总被引:3,自引:4,他引:3  
赵清  郑国强  黄巧华 《地理研究》2006,25(3):468-476
城市森林调查是城市森林研究和规划建设的前提和基础工作,而遥感和GIS技术已成为现代城市森林调查的主要方法。遥感信息源和遥感分类技术是决定城市森林遥感调查质量的两个关键因素,研究认为,根据城市森林特点及城市森林研究和规划建设的要求,城市森林遥感调查采用的遥感影像分辨率以810m为宜,神经网络模型分类技术应用于城市森林遥感调查效果较好。本文以南京市主城区为例,以10m分辨率多光谱spot卫星图像与2.5m分辨率全色spot卫星图像的融合图像作为解译信息源,采用dARTMAP神经网络模型进行监督分类,提取了一套具有较高精度的南京市主城区城市森林空间属性数据和图件,并在此基础上分析了南京市城市森林基本特点及规划建设方向。  相似文献   

13.
若尔盖湿地面临的威胁、保护现状及对策分析   总被引:11,自引:2,他引:11  
若尔盖湿地是中国残存面积最大的高原泥炭沼泽,具有丰富的生物多样性和生态资源。然而长期以来,这片湿地明显萎缩,生态环境极度脆弱,正面临着空前的生态危机。在分析了若尔盖湿地及其生物多样性面临的主要威胁,包括自然因素和人为因素的基础上,总结了若尔盖湿地保护现状,包括建立保护区、加强宣传、开展科研调查活动、以及各种保护项目和工程,并从国家层次、地方层次和保护区层次上提出了有效缓解若尔盖湿地面临威胁的对策。  相似文献   

14.
Tropical forests have been recognized as having global conservation importance. However,they are being rapidly destroyed in many regions of the world. Regular monitoring of forests is necessary for an adaptive management approach and the successful implementation of ecosystem management. The present study analyses the temporal changes in forest ecosystem structure in tribal dominated Malkangiri district of Orissa,India,during 1973-2004 period based on digitized forest cover maps using geographic information system (GIS) and interpretation of satellite data. Three satellite images Landsat MSS (1973),Landsat TM (1990) and IRS P6 LISS III (2004) were used to determine changes. Six land cover types were delineated which includes dense forest,open forest,scrub land,agriculture,barren land and water body. Different forest types were also demarcated within forest class for better understanding the degradation pattern in each forest types. The results showed that there was a net decrease of 475.7 km2 forest cover (rate of deforestation = 2.34) from 1973 to 1990 and 402.3 km2 (rate of deforestation = 2.27) from 1990 to 2004. Forest cover has changed over time depending on a few factors such as large-scale deforestation,shifting cultivation,dam and road construction,unregulated management actions,and social pressure. A significant increase of 1222.8 km2 agriculture area (1973-2004) clearly indicated the conversion of forest cover to agricultural land. These alterations had resulted in significant environmental consequences,including decline in forest cover,soil erosion,and loss of biodiversity. There is an urgent need for rational management of the remaining forest for it to be able to survive beyond next decades. Particular attention must be paid to tropical forests,which are rapidly being deforested.  相似文献   

15.
Tropical forests have been recognized as having global conservation importance. However, they are being rapidly destroyed in many regions of the world. Regular monitoring of forests is necessary for an adaptive management approach and the successful implementation of ecosystem management. The present study analyses the temporal changes in forest ecosystem structure in tribal dominated Malkangiri district of Orissa, India, during 1973–2004 period based on digitized forest cover maps using geographic information system (GIS) and interpretation of satellite data. Three satellite images Landsat MSS (1973), Landsat TM (1990) and IRS P6 LISS III (2004) were used to determine changes. Six land cover types were delineated which includes dense forest, open forest, scrub land, agriculture, barren land and water body. Different forest types were also demarcated within forest class for better understanding the degradation pattern in each forest types. The results showed that there was a net decrease of 475.7 km2 forest cover (rate of deforestation = 2.34) from 1973 to 1990 and 402.3 km2 (rate of deforestation = 2.27) from 1990 to 2004. Forest cover has changed over time depending on a few factors such as large-scale deforestation, shifting cultivation, dam and road construction, unregulated management actions, and social pressure. A significant increase of 1222.8 km2 agriculture area (1973–2004) clearly indicated the conversion of forest cover to agricultural land. These alterations had resulted in significant environmental consequences, including decline in forest cover, soil erosion, and loss of biodiversity. There is an urgent need for rational management of the remaining forest for it to be able to survive beyond next decades. Particular attention must be paid to tropical forests, which are rapidly being deforested.  相似文献   

16.
Abstract: This article examines recent changes to conservation in New Zealand. The argument is influenced by practical experience over the past 15 years, first as conservation planner employed by the Department of Conservation, then as an environmentalist involved in community conservation projects. The development of public‐private partnerships in conservation action over the past 15 years is reviewed. These changes point to the configuration of new landscapes, although the diverse and uncoordinated nature of many contemporary initiatives suggest that future biological communities will comprise a diversity of hybrid mixes from predominantly native to fully non‐native species.  相似文献   

17.
李程  庄大方  何剑锋  文可戈 《地理学报》2021,76(7):1634-1648
物候变化是气候变化的重要指示器,通过对植被物候时空变化的研究可以为进一步分析全球气候变化提供依据。基于2000—2017年MODIS-NDVI时间序列数据,利用不对称高斯函数和动态阈值法,提取、分析了东西伯利亚苔原—泰加林过渡带植被生长季起始期(SOS)、结束期(EOS)、中期(MOS)和长度(LOS)4种植被遥感物候参数的时空变化格局。同时结合同期CRU(Climate Research Unit)气温观测数据,分析了4种物候参数对气温变化的响应关系。结果表明:遥感物候参数可以直接、有效地反映气温的变化:研究区64°N以南区域4—5月气温升高,对应区域SOS提前5~15 d;64°N~72°N之间5—6月气温升高,对应区域SOS提前10~25 d;最北端北冰洋沿岸6月气温升高幅度较小且7月气温降低,对应区域SOS推后15~25 d;西北部8月、西南部9月气温降低,对应地区EOS提前15~30 d;67°N以南区域9—10月气温升高,对应区域EOS推后5~30 d;EOS的变化对气温变化较SOS更为敏感,较小的气温波动即引起EOS较大的变动;研究区内植被生长季整体呈前移趋势,且西北部LOS缩短,中部、南部LOS延长。  相似文献   

18.
针对当前生物多样性保护中存在的生态孤岛问题,提出陆域生物多样性保护区群网体系建设的设想,阐述了生物多样性保护区群网体系的基本概念,各种尺度体系的主要任务和功能,并设计了体系的初步框架,以期充分利用自然保护区外一切利于生物多样性保护的地域空间和条件,从生态系统整体性、空间关联性和不同尺度、不同层次、不同性质的保护性地域的协调整合上,建构一个用地节约且效能较高的生物多样性保护空间。通过实证,从县域、省域、省际不同的空间尺度探索生物多样性保护区群网体系的建构。县域尺度以福建省明溪县生物多样性保护体系为例,分析了各类自然保护实体空间的协调和保护以及主生态廊道的架构;省域尺度以福建省生物多样性保护空间群网体系构建为例,在增补生物多样性保护重点节点的基础上,探索了地域上分割的同类或相关生物多样性保护空间的网络连接;省际尺度以中国南方华南虎潜在分布区生境廊道构建为例,探索华南虎种群生存空间体系网络架构。  相似文献   

19.
Mangrove forests in Southeast Asia provide many ecosystem services, though are experiencing extensive deforestation, especially in Myanmar. Recent political and economic reforms in Myanmar are projected to further increase development pressures on natural resources. Mangrove forests in the southern state of Tanintharyi have largely been spared clearance because of poor infrastructure and a volatile security situation, though this may change with plans for economic expansion. We quantified land cover dynamics and proximate drivers of mangrove deforestation in Tanintharyi between 1989 and 2014 using a remote sensing approach over five time intervals. Tanintharyi experienced low mangrove cover loss overall, as compared with other regions of Myanmar, with 3.2 per cent being deforested over 25 years. However, this statistic hides large site‐specific losses and gains, which varied significantly within the study area. Myeik district lost 210 km2 of mangrove over 25 years, but also gained 132 km2. Dawei and Kawthung had minimal net loss of mangroves because of extensive mangrove regeneration. This historical mangrove baseline is essential for supporting environmentally‐conscious development in Myanmar's southernmost state.  相似文献   

20.
3S技术在野生动物生境研究中的应用   总被引:13,自引:0,他引:13  
3S技术可快速、准确、实时地获取、处理空间信息,具有广泛的应用性。该文从野生动物生境格局、生境破碎化、生境因子特性、生境分析模型建立、生境评价和生境恢复建设等方面,综合评述野生动物生境研究中3S的应用问题,并提出野生动物生境研究将朝着3S技术集成、GIS与数学模型结合、数据可视化模拟、网络化和智能化的方向发展。  相似文献   

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