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1.
基于阈值分割的黑龙江省森林类型遥感识别 总被引：1，自引：0，他引：1
全球变化背景下,准确获取森林覆盖是监测森林资源动态、实现林业可持续发展的重要基础。为将省级尺度森林资源清查面积资料空间化,以黑龙江省为例,利用1999-2003年该省森林资源清查面积数据,结合2000年500 m分辨率的MODIS数据,构建了基于阈值分割的森林类型遥感识别方法。该方法利用不同地表覆被类型归一化植被指数时间序列的季节分异特征,以森林资源清查面积为标准,设定森林类型的划分阈值,识别了黑龙江省森林类型的空间分布。最后,基于分层随机抽样和精度评价方法,表明森林类型识别结果与地面参考数据具有较高的一致性,总体分类精度为78.1%;特别是季节特征明显的落叶林,精度可达80%以上。本文所构建的方法可将森林清查统计数据进行准确的空间定位,同时结合多期森林资源连续清查资料和遥感信息,可为识别并量化区域生态系统生物量和碳库变化等提供科技支撑。 相似文献
2.
分区控制和分层提取下的OMIS-I影像土地利用/覆盖分类方法研究 总被引：1，自引：0，他引：1
针对宜兴试验区128波段OMIS—Ⅰ机载成像光谱数据,在平原区、山区分区基础上建立多级分层决策树综合分类方法。通过该方法可实现对土地利用／覆盖一级类（林地、园地、水域、耕地）自动分类,精度达88．15％,Kappa指数为0．82,园地漏分率最高（20．23％）,耕地漏分率最低（2．24％）;耕地、林地、园地、水域的错分率分别为21．87％、21．98％、0．66％、0。土地利用／覆盖二级分类也可采用分层自动分类,其总体精度达86．16％,Kappa指数为0．81。采用土地利用矢量数据辅助和人工目视解译对部分二级类别进行细分,可获得更加可靠的分类结果。研究表明,分区控制下的多级分层决策树综合分类方法应用于OMIS—Ⅰ高光谱影像土地利用／覆盖分类,具有可操作性和较高的精度。 相似文献
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4.
中南半岛森林覆被变化研究进展 总被引：1，自引：0，他引：1
中南半岛森林覆被是热带地区极为重要的自然资源,对当地生态环境和社会经济发展都有重要影响。本文从遥感监测与制图、时空变化格局、影响因素和生态环境效应4 个方面,系统总结和评述了中南半岛森林覆被变化的研究进展,并对研究问题和发展方向进行了讨论。研究表明：①中南半岛森林覆被遥感监测数据源由光学遥感逐渐转向雷达遥感,监测方法向采用多分类器和多源信息转变,监测对象主要是天然森林覆被,人工林监测仍面临多重困难;②1980-2010 年期间,中南半岛不同地区森林覆被变化时空差异明显,其中,在1990 年前森林覆被面积为净增加,之后净减少;在空间上,泰国、老挝、缅甸和柬埔寨森林面积在1990 年后均持续减少,只有越南呈增长趋势;③中南半岛森林覆被变化的直接驱动因素主要为经济林扩张、刀耕火种农业、道路建设和商业采伐,间接驱动因素包括人口、社会经济和政策等因素,主要表现为森林数量变化、森林退化和森林再生/恢复等方面,其程度与干扰方式、强度、频率直接相关;④中南半岛森林覆被变化的生态环境效应主要体现在水分效应、大气环境效应、土壤效应和生物效应4方面。 相似文献
5.
2000—2010年亚欧大陆中低纬度海岸带土地利用/覆盖变化及驱动力分析 总被引：2，自引：1，他引：1
土地利用/覆盖变化是全球变化研究的重要问题,而海岸带则是该领域研究的热点区域。以三套土地利用/覆盖数据（MCD12Q1、CCI-LC和GlobeLand30）为基础,采用基于一致性分析和模糊集合理论的数据融合方法,获取2000年和2010年亚欧大陆中低纬度海岸带土地利用/覆盖分类信息,进而分析土地利用/覆盖变化特征及驱动因素。结果表明：十年间亚欧大陆中低纬度海岸带土地利用/覆盖变化方式主要以耕地萎缩和林地扩张为主,其次是湿地扩张,再次是草地和裸地萎缩,最后是灌木地和人造地表扩张;土地利用/覆盖类型之间的相互转换面积较小,仅占研究区总面积的4.22%,其中分布面积占优势的变化类型为耕地–林地–草地相互转换、灌木地–裸地相互转换、林地转为湿地以及林地转为灌木地等。地形因素、气候分异等自然驱动力深刻影响着土地利用/覆盖变化的宏观格局,而人口压力增大、经济高速发展、政策的颁布与实施等人文驱动力则是推动十年间亚欧大陆中低纬度海岸带土地利用/覆盖变化的主要原因。 相似文献
6.
Michael Emch James W. Quinn Marc Peterson Mark Alexander 《The Professional geographer》2005,57(2):256-267
Measuring land‐cover change is an essential part of sustainable conservation planning. This project uses Landsat MSS and ETM+ data to document forest cover change in the Toledo District, Belize, from 1975 to 1999 and provides an initial assessment of why these changes took place. Supervised and subpixel classification methods were employed. The results showed an aggregate forest loss of almost 10 percent, which is approximately 36,000 ha. Deforestation expanded significantly in the most populous Mayan areas of central Toledo District and along the Guatemalan border. Subpixel classification results showed that in 1999 the most densely forested areas were in northern Toledo District in the Maya Mountains. 相似文献
7.
Tourism is Nepal's largest industry, giving people in rural areas an alternative to subsistence farming. Tourism can have an impact on the forest cover of a region as trees provide firewood for cooking and heating and timber for building accommodation. In 1986 the Annapurna Conservation Area Project was established to ensure that tourism was managed more sustainably, which includes minimising its impact on the forest cover. This study assesses the impacts of tourism on the forest cover in the Annapurna region by comparing Landsat images from 1999 to 2011. This was achieved through spectral classification of different land cover and by assessing the change in forest cover in relation to increasing distances from tourism villages. A major problem with remote sensing in mountainous regions such as Nepal is shadow caused by the relief. This issue was addressed by only assessing areas which were free from shadow, which in effect meant a sample was used rather than the whole study region. The results indicate that there has been an 8 percent reduction in overall forest extent, but this change varies by region. In the northern, drier regions there has been a net increase in forest cover, while in the southern regions there has been a net reduction in forests. The influence of tourism facilities on forest is also variable. Around each of the tourism villages sampled there was a general trend of forest removal decreasing as the distance from each village increased, which indicates tourism does have a negative impact on forests. However, there was an opposite trend in the northern villages that were well inside the conservation area. 相似文献
8.
Thi Thuy Hanh Nguyen 《Singapore journal of tropical geography》2019,40(3):452-475
This study identified spatial patterns of forest change in Hoa Binh, Vietnam, from 2005 to 2017 by integrating Landsat data and Geographic Information System (GIS) data. A Multiple Logistic Regression (MLR) model was adapted to analyse drivers of three types of forest change, including (i) deforestation and forest degradation, (ii) forest regrowth and (iii) plantation expansion. The results reveal that accessibility and local economic development were determinants of forest cover dynamics during the integration and globalization period and that increased population pressure and poverty were no longer the main factors in forest cover transition. Several key policies in this time period positively affected forest cover change, triggering private sector participation in developing the forest economy by including households and small and medium enterprises in particular. The findings of this study can provide learning points for the implementation of sustainable forest management policies in other Vietnamese provinces or in neighbouring countries. This research has provided an effective tool for visualizing human‐forest ecosystem interaction, and this tool can be applied to subsequent studies to determine causes of forest cover change at the provincial level in Vietnam. 相似文献
9.
The Koshi River Basin is in the middle of the Himalayas, a tributary of the Ganges River and a very important cross-border watershed. Across the basin there are large changes in altitude, habitat complexity, ecosystem integrity, land cover diversity and regional difference and this area is sensitive to global climate change. Based on Landsat TM images, vegetation mapping, field investigations and 3S technology, we compiled high-precision land cover data for the Koshi River Basin and analyzed current land cover characteristics. We found that from source to downstream, land cover in the Koshi River Basin in 2010 was composed of water body (glacier), bare land, sparse vegetation, grassland, wetland, shrubland, forest, cropland, water body (river or lake) and built-up areas. Among them, grassland, forest, bare land and cropland are the main types, accounting for 25.83%, 21.19%, 19.31% and 15.09% of the basin’s area respectively. The composition and structure of the Koshi River Basin land cover types are different between southern and northern slopes. The north slope is dominated by grassland, bare land and glacier; forest, bare land and glacier are mainly found on northern slopes. Northern slopes contain nearly seven times more grassland than southern slopes; while 97.13% of forest is located on southern slopes. Grassland area on northern slope is 6.67 times than on southern slope. The vertical distribution of major land cover types has obvious zonal characteristics. Land cover types from low to high altitudes are cropland, forest, Shrubland and mixed cropland, grassland, sparse vegetation, bare land and water bodies. These results provide a scientific basis for the study of land use and cover change in a critical region and will inform ecosystem protection, sustainability and management in this and other alpine transboundary basins. 相似文献
10.
Long-term temperature data on a soil layer 3.2 m in thickness have been used in the differentiation of a topographically highly complicated permafrost on the territory of Transbaikalia. It was found that the geographical ranges are most clearly identified from mean annual temperature values. The schematic map displays the areas with the temperatures –4 to–1°C,–1 to 1°C and 1 to 4°C which are in good agreement with the permafrost distribution pattern (continuous and discontinuous permafrost, and permafrost islands). A classification of the thermal conditions of soils is carried out according to the highest mean monthly temperature at all depths. We identified four types which are characterized by the qualitative assessment as warm, moderately warm, cold and very cold. A relevant cartographic model shows the distribution of the thermal regime of soils for a warm season. The dot method was used to provide a clear display of available information on soil temperature, and it was possible to show the existence of small areas of the types of thermal regime and their fragmentation. Current changes in soil temperature were determined for August, which are in good agreement with regional changes in ground air temperature. In either case, we observed positive linear trends. Assessments of thermal resources of the soil layer and their geographical patterns belonging to the widespread depression-valley and valley natural systems as well as to the relatively planate surfaces of Transbaikalia can be used for scientific and practical purposes. 相似文献
11.
基于地表覆盖物光谱特征的土地覆被分类系统 ——以鄱阳湖流域为例 总被引：8，自引：1，他引：7
土地覆被主要表现为陆地表面的形态特性和动态变化特征,土地利用是其动态变化的外在驱动力,植被是土地覆被的“主要”而非唯一的组成部分,土地覆被也包含着它的功能特性。地表覆被物的光谱特征及其季节性变化规律是土地覆被的本质特征,也是土地覆被分类的基本依据之一;利用遥感资料所表达的地表覆被物特征值 (如以NDVI为指标的绿度值、始绿期、终绿期、波形、峰值、谷值等) 可以方便地对土地覆被分类标准进行量化处理;对于一些复杂的复合单元,应着重于它的组合 (包括组成成分和结构) 特性及其对地面过程的影响来赋予更确切的内涵。据此,构建了包含7个一级类别和20个二级类别的开放式 (open-end) 的鄱阳湖流域土地覆被分类系统,并且应用SPOT4-VEGETATION 的时序NDVI数据,对各类别的面积比重进行了分析,结果显示鄱阳湖流域的现状覆被主要由常绿覆被和作物-树-草混合覆被以及人工栽培植被 (作物) 等构成。 相似文献
12.
基于土地利用/覆被分类系统估算 碳储量的差异——以海南岛森林为例 总被引：9，自引：1，他引：8
土地利用/覆被分类系统是碳蓄积研究的依据,然而各种碳蓄积研究所采用的土地利用/覆被分类系统不尽相同。根据1993年海南林业资源二类调查资料,我们按照USGS土地利用/覆被、LCCS土地覆被和中国科学院土地资源三种分类系统所定义的类别进行分类并计算了各自的碳储量和碳密度,为碳储量的进一步精确估算和土地覆被分类系统研制提供重要的科学依据。结果发现,（1）不同的土地利用/覆被分类系统所对应的总碳储量以及平均碳密度都有了明显的差别。林业调查资料的植被分类、FAO 土地覆被分类系统(LCCS)、USGS 土地利用/土地覆被分类系统以及我国学者常用的中国科学院土地资源分类系统的碳蓄积量(Tg C)分别是28.98、28.71、21.04和21.04;碳密度(t C/ha)分别是31.24、30.95、22.68和22.68。（2）土地利用分类系统和土地覆被分类系统之间的结果具有较大差异,其碳储量相差7.67～7.94 Tg C,碳密度则相差8.27～8.56 t C/ha;差距在26.47%～37.74%之间。与其他学者研究结果比较发现,土地利用/覆被分类系统造成的碳蓄积差异的变化方向是不定的,取决于具体的分类系统和材积-生物量函数。不同土地利用/覆被分类系统对于植被划分的不同,导致了材积-生物量回归方程和类别面积的差异是造成碳蓄积和碳密度估算差异的根本原因。目前常用的土地利用/覆被分类系统在估算碳蓄积中存在一定问题,不适合于高精度的碳蓄积计算。体现地表植被生物量差异、植被叶型和外貌特征、种类及树龄差异等内涵的土地利用/覆被分类系统利于陆地碳循环研究的深化。 相似文献
13.
热带森林覆被的时空动态评价——以印度Malkangiri district of Orissa为例 总被引：1，自引：1，他引：0
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
14.
基于Landsat 8 OLI数据与面向对象分类的昆嵛山地区土地覆盖信息提取 总被引：1，自引：0，他引：1
利用2015年Landsat 8 OLI遥感影像和DEM作为分类数据源,结合野外调查数据,采用面向对象的分类方法对昆嵛山地区土地覆盖信息进行提取,并对分类结果进行精度评价与比较分析。研究表明：面向对象分类方法提取的各地类连续且边界清晰,分类效果与实际情况基本吻合。昆嵛山地区占主导地位的土地覆盖类型是针叶林,面积为1 546.81 km2。研究区土地覆盖分类的总体精度和Kappa系数分别为91.5%和0.88,其中针叶林、草地、水体和建设用地的生产者精度均达到87%以上。相对于监督分类方法,本研究提出的土地覆盖信息提取方法的总体分类精度和Kappa系数分别提高14.7%和0.17。基于面向对象的中分辨率遥感影像,能够获取较高精度的土地覆盖信息,为大范围土地覆盖分类研究提供方法参考。 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.
全球及区域模式中陆面过程的地表植被覆盖分类方法 总被引：1，自引：0，他引：1
全球和区域尺度上陆面生态系统与气候密切相关。全球和区域模式的发展对于我们认识气候与陆地生态的变化起到重要作用。在这些模型中，植被覆盖是影响大气-植被间热量、水分和CO2等交换的重要陆面参数。在分析了陆地植被覆盖分类原理基础上，介绍了目前全球不同植被覆盖分类方案，包括基于地基观测的植被分布、基于生物气候特征的分类方案（如：Holdridge的方案）；特别近年来陆面过程试验表明，各种遥感数据源（如：NOAA—AVHRR，EOS—MODIS，Landsat—TM）等为我们提供了有利的工具来监测全球植被动态，完善植被分类，并且采用高时空分辨率的全球土地覆盖状况特征，在不同时空尺度揭示植被-大气相互作用。本文分析了代表性的3种基于卫星遥感技术的陆面植被分类方案，分别是BATS（18类）、SIB（9类）、SIB2（12类）和BIOME—BGC（31类）陆地模式的植被覆盖分类方案．最后分析了目前可用于全球植被覆盖分类的新的遥感数据库。 相似文献
17.
基于MODIS数据的北京西北部地区土地覆盖分类研究 总被引：7，自引：1，他引：6
本文主要基于MODIS 16天合成的NDVI时间序列数据、8天合成 LST数据、1∶5万DEM数据以及其他辅助数据相结合,进行北京西北部地区土地覆盖分类的研究。首先选取适合于MODIS数据分类的土地覆盖分类系统,然后用PCA方法对NDVI时间序列数据进行信息增强与压缩处理,以排除各种干扰因素,提高分类精度。最后结合LST数据、DEM数据及降雨温度数据,利用?齂-均值非监督分类法,进行研究区的土地覆盖分类,经过分类后处理,得到北京西北部地区的土地覆盖分类图。分类结果表明,使用250m分辨率MODIS数据,结合本文所用方法,能够实现较大区域的土地覆盖分类,并且能达到较高的分类精度。 相似文献
18.
Tom Akkermans Anton Van Rompaey Nicole Van Lipzig Pieter Moonen Bruno Verbist 《自然地理学》2013,34(6):417-440
State-of-the-art impact-modeling studies in environmental and climatological sciences require detailed future deforestation scenarios that allow forest to be replaced by a mosaic of multiple successional land-cover types, rather than the simple conversion of forest to a single land-cover type, such as bare soil or cropland. Therefore, not only the amount and location of forest removal has to be known (as is typically provided by scenarios), but also knowledge about the successional land-cover types and their relative areal proportions is needed. The main objective of this study was to identify these successional land-cover types and quantify their areal proportions in regions deforested during the past 37 years around the city of Kisangani, D.R. Congo. The fallow vegetation continuum was categorized in different stages, adapted from existing classifications. Ground-truth points describing the present-day vegetation were obtained during a field campaign and used for supervised and validated land-cover classification of these categories, using the Landsat image of 2012. Areal proportions of successional land-cover types were then derived from the resulting land-cover map. The second objective of this study was to relate these areal proportions to time since deforestation, which is expected to influence fallow landscapes. Landsat images of 1975, 1990, and 2001 were analyzed. Present-day mature tree fallow is less abundant on areas deforested during 1975–1990. The relative areal proportions were used to refine a deforestation scenario and apply it to existing data-sets of LAI and canopy height (CH). Assuming a simple conversion of forest to cropland, the deforestation scenario projected a reduction of grid-cell-averaged CH from 25.5 to 7.5 m (within deforested cells), whereas the refined scenarios that we propose show more subtle changes, with a reduced CH of 13 m. This illustrates the importance of taking successional land cover correctly into account in environmental and climatological modeling studies. 相似文献
19.
Land use/cover, landforms and fragmentation patterns in a tropical dry forest in the southern Pacific region of Mexico 总被引：1，自引：0，他引：1
Leopoldo Galicia Alba Esmeralda Zarco-Arista Karla Ivette Mendoza-Robles José Luis Palacio-Prieto Arturo García-Romero 《Singapore journal of tropical geography》2008,29(2):137-154
In spite of widely documented studies of deforestation rates and land use/cover changes in tropical dry forests in Mexico, relatively little is known about fragmentation patterns in such forests. This study defines the spatial distribution of landforms and land use/cover types the lower Papagayo River basin and examines their influence on fragmentation patterns and biological diversity in a tropical dry forest in that southern Pacific region. The land use/cover map was constructed from aerial photographs, Landsat TM imagery (2000) and fieldwork. Landform units were defined based on altitude, slope, lithology and morphology. Landscape fragmentation parameters were obtained using FRAGSTATS (version 3.3) considering the numbers of patches, mean, minimum and maximum patch size, edge density, total edge and connectivity. Results show tropical dry forest to be remnant vegetation (~11 per cent), characterized by isolation and low connectivity. Land use/cover types have different effects on fragmentation patterns. Agriculture and cattle raising produce similar numbers of patches, but with a different mean size; and human settlements have a scattered distribution pattern. The abandonment of rural agricultural livelihoods has favoured the expansion of secondary tropical dry forest characterized by continuity and high connectivity, which suggests a high regeneration potential from land abandonment. It can be concluded that tropical dry forest fragmentation and recovery at regional scales depend on such landscape attributes as lithology, slope, geomorphology and management. 相似文献
20.
Monitoring the change in land cover in natural places, such as ecotones, has become an important tool for forest management, especially in protected areas. The present work analyses the spatial and temporal changes in forest cover in Moncayo Natural Park (Spain) from 1987 to 2010 using remote sensing techniques, geographical information systems (GIS) and quantitative indices of landscape ecology. Four Landsat images were used to map nine representative land cover categories in this preserved area in both years. The overall classification accuracies in land cover cartographies in 1987 and 2010 were 87.65% and 84.56%, respectively. Landscape metrics obtained at the landscape level show an increase in fragmentation and, as a result, an increase in landscape spatial diversity. Focusing on the class level, the results show a forest expansion of sessile oaks (Quercus petraea) and beech forest (Fagus sylvatica), two important bioclimatic indicators in this natural park, because they are the southernmost locations for these species in Europe. The decrease of mainly introduced pine forest and the transformation of mixed shrub areas into natural forested areas explain the aforementioned increase in fragmentation. These results are in agreement with the strategies for nature conservation designed by forest managers during the period evaluated. 相似文献