基于决策树分类方法的城市绿化分析——以兖州地区Hyperion遥感影像为例

以兖州实验区为例,探讨了利用决策树方法进行城市高光谱遥感绿化分析的流程和方法;分析了试验区典型地物的波谱特性;总结了常用反射率反演方法,并根据具体情况选择FLAASH模型进行了实验;试验区研究表明,决策树分类方法在高光谱遥感影像信息提取中具有可行性.这种基于高光谱的精细信息提取方法,可以提高不同植被类型的高光谱图像分类识别精度,为城市绿化分析提供参考依据.     

用卫星影像密度值估测森林蓄积量

<正> 卫星照片是一种多波段影像。同普通照片一样,也是以底片上的密度差异记录被拍照物的光反射特性,显示被拍物体几何形状的。与普通照片不同的是,它对同一物体以多个(本研究用卫片是4个) 波段的方式进行记录,得到多张底片,每张底片只记录一个特定波段的地物反射特性,因而同一物体在各张底片上密度分布是不同的。正是由于这一点,卫星影像给我们提供了区分各种地物的可能性。本研究是通过卫片的影像密度值来估测森     

基于移动窗口法的苗二河流域森林景观格局分析

基于移动窗口法,对2014年苗二河流域森林景观格局进行分析。结果表明:非林地和有林地为优势地类景观,面积大,斑块形状较复杂,分布广泛;无立木林地为劣势地类景观,面积小,斑块形状较规则,分布比较集中;森林景观适宜景观粒度为150 m;森林景观适宜窗口尺度为900 m。基于粒度效应、面积信息损失精度和移动窗口法对苗二河流域森林景观格局的研究,可为优化流域森林景观提供参考。     

粒度变化对苗二河流域森林景观异质性影响研究

该文利用Fragstats和ArcGIS计算苗二河流域森林景观特征和不同景观粒度下森林景观异质性指数,研究分析得出以下结论:1)苗二河流域有林地和非林地景观为优势地类,分布比较广泛;无立木林地面积小,分布比较集中;其它地类景观为劣势地类;2)随着景观粒度增加,苗二河流域森林景观斑块形状越来越规则。景观中斑块数量较多,形状不规则,边缘曲折迂回程度较高。该指数同时反映出苗二河流域景观斑块聚集和离散程度,表明随着景观粒度增加,斑块呈现聚集状态;3)随着景观粒度的增加,平均分维数整体趋近于1,苗二河流域斑块形状周长较简单,趋于正方形等简单形状;4)随着景观粒度增加,聚合度指数不断下降,苗二河流域景观斑块破碎化程度不断上升。通过森林景观特征和不同粒度景观异质性分析,为科学合理规划建设苗二河流域森林景观提供指导。     

红树林资源调查的遥感图象处理方法研究

在2001年应用“3S”技术与地面调查相结合的方法进行了广西红树林资源调查。以SPOT-HRV和Landsat 7 ETM 数据为信息源，采用1：1万地图形和GPS定位数据进行SPOT图象的几何精校正，并采用精校正后的SPOT图象对ETM 图象进行精校正。通过训练区对图象进行拉伸增强，然后采用锐化HIS变换的方法将SPOT图象与ETM 图象进行复合，经真彩色合成后得到的图象具有地物轮廓清晰、色彩丰富、层次分明的特点，红树林与滩涂、海域的区别十分明显，为红树林分布位置和边界的准确定位奠定了坚实的基础。     

对成数抽样中三种地类调查方法的浅析

<正> 在成数抽样中,确定总体中样本单元(样地)地类的方法通常有:1.中心地类法;2.优势地类法;3.样地十分法。本文试按数理统计方法、用我省森林资源连续清查第一付总体的资料,对上述三种方法进行分析和比较。一、调查方法我省“连清”第一付总体设有9654个样地。为2×2公里网交叉点系统布点,用罗盘仪从明显地物标引线定点,对角线法开设面积     

杉木叶绿素含量高光谱遥感模型研究

利用高光谱技术,探索杉木成熟林反射光谱与其叶绿素含量之间的相关关系。以湖南省攸县黄丰桥国有林场杉木成熟林为对象,采用美国ASD公司生产的手持式野外光谱仪(波长325~1 075 nm)进行地面和空中的杉木冠层波谱观测,采集到有效观测数据44条,并同步展开叶绿素总量分析。采用ViewSpec Proversion 4.02、SPSS17.0统计软件、MATLAB软件、EXCEL数据分析工具对波谱数据进行处理和生化成分相关性分析,建立了叶绿素总量与反射光谱关系模型,通过模型检验,得到杉木叶绿素总量的高光谱模型为:y=0.291x395+20.172x521+0.758。     

基于遥感分层技术的平南县森林蓄积抽样调查方法研究

采用遥感数据辅助分层可解决分层抽样在大范围森林资源调查中分层面积不准确的缺点.以ALOS数据为基础,将平南县的森林资源分为A层（有林地、疏林地层）和B层（其它地类层）.在各层内机械预布设样地,比较预布样地缓冲区（角规控制检尺所能绕测到的最大范围）的SAVI值、DNN IR值及对明显地物的目视解译,确定各样地缓冲区的地类,A层样地数有578个,B层有978个.根据分层抽样各层所需样本数,在确定好地类的样地中,随机抽取各层所需样本数并调查其蓄积量.结果表明,抽样的估计精度为91.5%,全县森林蓄积量为5 900 186.7 m3.     

基于MERSI数据的山西森林覆盖监测

利用FY3-3A/MERSI可见光和近红外波段数据合成得到假彩色卫星数字图像,结合区域土地利用、植被类型及森林资源分布等数字化图件,在对图像进行目视解译及多波段数据非监督分类基础上,将地物覆盖划分为林地、冬小麦、水体和裸地4种类型;采用4种监督分类方法(最大似然分类法、平行算法、最小距离法和马氏距离法)进行地物分类;在分析分类结果可行基础上,依据区域森林覆盖数字化图件对林地分类结果进行精度评估,确定研究区域林地空间分布结果.结果表明:4种监督分类方法中,最大似然分类法分类结果的精度最高,达到85%,其次是最小距离和马氏距离法,平行算法的结果较差.可见,利用MERSI数据采用监督分类和非监督分类相结合的方法提取的山西省森林资源分布结果精度较高,符合实际情况,可作为区域宏观森林资源分布监测的有效手段.     

纳板河流域不同森林类型林分直径分布结构特征研究

在纳板河流域的5种森林类型中设置大样地14块,采用负指数函数模型和q值分布函数,研究不同森林类型的林分直径分布结构特征,以此探究纳板河流域森林群落的生长状况。结果表明,整个流域中的森林群落拟合模型均表现出近似双曲线形式中的局部反“J”型曲线形式,大量林木直径分布在10径阶,不同森林群落的负指数拟合效果较好,其中拟合效果最好的为季风常绿阔叶林。从a值、k值、q值的测算结果得出森林群落次生能力由强到弱的顺序为热带雨林群落、热带季雨林群落、季风常绿阔叶林群落、山地雨林群落、落叶阔叶林群落。     

A general classification of agroforestry practice

Present classification schemes confuse agroforestry practices, where trees are intimately associated with agricultural components at a field scale, with the whole farm and forest systems of which they form a part. In fact, it is common for farming systems to involve the integration of several reasonably discrete agroforestry practices, on different types of land. The purpose of a general classification is to identify different types of agroforestry and to group those that are similar, thereby facilitating communication and the organized storage of information. A new scheme is proposed that uses the ‘practice’ rather than the ‘system’ as the unit of classification. This allows an efficient grouping of practices that have a similar underlying ecology and prospects for management. A two stage definition of agroforestry is proposed that distinguishes an interdisciplinary approach to land use from a set of integrated land use practices. Four levels of organization are recognized through analysis of the role of trees in agricultural landscapes: the land use system, categories of land use within systems, discrete groups of components (trees, crops, animals) managed together, and functionally connected groups of such discrete practices in time and space. Precedents for this form of analysis are found in the literature and it conforms with generally accepted methods of systems analysis. Classification of major types of agroforestry practice proceeds primarily according to the components involved and the predominant usage of land. A secondary scheme further classifies these in terms of the arrangement, density and diversity of the tree components involved. This revised version was published online in June 2006 with corrections to the Cover Date.     

林区不同土地利用模式对土壤理化性质与酶学特性的影响

土壤在调节地球气候和物质循环方面起着重要作用,但是由于人为因素的影响,不当的土地经营模式（如居民用地、农业耕地、毁林开荒）对土壤质量产生了深刻影响,使土壤质量发生变化。本研究对黑龙江省尚志市帽儿山林场的4种不同的土地利用与经营模式（森林土壤、农田土壤、场部用地和森林迹地）下的土壤理化性质和土壤酶活性进行测定与分析,探讨不同土地利用模式对其土壤理化与土壤酶学特性的影响。研究发现4种土壤类型的10个采样点的10个土壤理化指标和5个土壤酶活性指标间存在显著差异,土壤质量从高到低依次为：森林土壤,森林迹地,林场场部用地,农田用地。相关分析表明土壤脲酶和过氧化氢酶与土壤含水量、土壤全氮、土壤全碳、土壤有机碳、可溶性全碳和可溶性有机碳含量之间成显著正相关;多酚氧化酶与土壤pH成显著正相关。因此,不同土地利用方式对土壤理化性质和土壤酶活性产生显著影响。     

乡村土地开发对森林生态系统服务功能的影响

根据马家河乡2005年和2010年的土地开发利用数据,采用Costanza提出的生态系统服务功能价值(ESV)计算方法,对其不同利用类型土地的森林生态系统服务功能及森林生态系统单项服务功能的价值进行评估。结果表明:马家河乡土地利用类型变化中,以林地、居住及建设用地等类型变化为主。其中,林地面积减少的最多,其所占国土总面积的比例减少幅度达到11.94%;其次为耕地面积,减少了3.02%;果园、草地水域的面积基本保持不变;而居住及建设用地增幅最大,达到了8.14%。马家河乡土地的森林生态系统的服务功能价值以林地价值减少最多,达到664.5元;果园价值减少459.77元;耕地价值减少188.97元;草地价值减少了64.39元;水域、居住及建设用地和未利用地的价值有不同程度的上升。马家河乡森林生态系统单项服务功能价值中除了森林游憩保健服务功能的价值有所上升,其余各项服务功能的价值均有不同程度地下降。     

Soil properties and physiographic factors controlling the natural vegetation re-growth in a disturbed catchment of the Central Spanish Pyrenees

Large changes in land use have occurred in the Central Spanish Pyrenees during the twentieth century. This mountain area supported an intense human use since the Middle Ages, that greatly transformed the natural landscape. The land uses changed dramatically during the first half of the twentieth century, due to major socioeconomic forces which lead to depopulation and land abandonment. Since then, a process of natural vegetation recovery has taken place. The anthropogenic impact during centuries deteriorated the soil quality, threatening the sustainability of agroecosystems and the natural vegetation re-growth. In this study, a soil survey was performed to identify the soil types and the physico-chemical properties of the soil that are relevant for maintaining the soil function for the recovery of vegetation after land abandonment. The study was conducted in the Arnás River catchment, which is representative of the region. The highest cation exchange capacity (CEC), nutrients, water retention, water availability and infiltration rates, as well as the lowest pH and carbonates, occurred in Lithic Hapludolls and Calcic Haploxerolls at the shady aspect, under a forest cover. Lithic Ustochrepts and Lithic Xerorthents on the sunny aspect, which were covered by shrubs, were of lesser quality than were the deeper and better-developed soils on the shady aspect. This is seen as an evidence of different patterns of soil degradation, which conditioned the re-growth of natural vegetation after land abandonment. The results provide insights into the main soil factors that have affected the re-establishment of natural vegetation in recent years. Recommendations are given for designing effective strategies for soil conservation after land abandonment in similar mountain environments.     

National assessment of the evolution of forest fragmentation in Mexico

This paper presents assessments of the fragmentation of the temperate and tropical forests in Mexico at the national level for two dates 1993 and 2002. The study was based on land use and vegetation cover data sets scale 1:250,000. Two broad forest types (Temperate Forests and Tropical Forests) and five more specific forest types (Broadleaf Forests, and Coniferous Forests; Tropical Dry Deciduous Forests, Tropical Sub-evergreen Forests, and Tropical Evergreen Forests) were defined to conduct the analyses. FragStats 3.3 was used to estimate nine metrics of the spatial pattern of the forests for each forest type and date considered. The results indicate that the land cover transitions that have occurred between 1993 and 2002 have resulted in more isolated forest patches with simpler shapes in both the Temperate and Tropical Forests. The remaining Tropical Forest patches have become smaller and more numerous. In contrast, the remaining Temperate Forest patches are fewer and on average larger. Of the more specific forest types defined in this study, the Broadleaf Forests have the highest indicators of fragmentation. However these forests are usually embedded or adjacent to Coniferous Forests. Of more concern for conservation purposes are the high values of fragmentation metrics found for the Tropical Evergreen Forests and Tropical Dry Deciduous Forests, because these forest types are usually surrounded by non-forest land covers or anthropogenic land uses.     

A United States View on Changes in Land Use and Land Values Affecting Sustainable Forest Management

Summary

With increasing opportunity costs of keeping land in forests because of increasing values for other land uses, such as for developed uses, forest ownership may become less attractive for some landowners and the return on investment less viable for both private and public landowners. This raises the question of what will become of the forests and the resources the forest supports, such as water and wildlife, if owners of the forests find it too costly to manage the forest. Land markets provide evidence on revealed behavior about what people are willing to actually pay for a bundle of rights necessary to gain access to land that can provide forest-based goods and services into perpetuity. However, owing to market failures and the nature of some forest land values, markets do not always reveal true forest land values, as discussed below. Allocation of land by use and cover types is a key determinant in sustainable forest management, with changes in land values providing important signals to land managers. Land valuation differs under market-oriented economies, emerging values in transition economies, and administered values in countries with command economies and is influenced by interactions between the environment and humans, including land ownership, use, and management.     

论沙化土地的治理

乌拉特前旗属干旱、半干旱地区,地貌类型复杂多样,造林立地条件较差。恶劣的自然条件,使大量土地日趋沙化,直接影响着这些地区的造林成活率和保存率的提高。文章对当前制约造林的沙化土地因素进行调查分析,提出治理的具体措施,可为同类地区提供造林技术参考。     

Tree planting for poverty reduction in less-favoured areas of the Ethiopian highlands

This paper assesses the potential impact of planting of eucalypt trees as a strategy to reduce poverty in a less-favoured area of the highlands of Ethiopia. Results from simulations with a bio-economic model for a less-favoured case study area in the highlands are combined with survey data at community, household and plot level to assess how general the results of the bio-economic model are. Application of the bio-economic model shows clearly that land degradation, population growth, stagnant technology and drought threaten food security. Household welfare and land quality are deteriorating rapidly in the area and interventions are urgently needed to avoid human disaster. Planting of eucalypts on land unsuitable for crop production may substantially increase household incomes if market outlets for trees can be found. Tree planting will not have severe negative effects on food production or land conservation. A policy combining promotion of tree planting and conservation of cropland may achieve win-win benefits in terms of increased household incomes as well as more sustainable land-use. Analysis of survey data from the Amhara Region of Ethiopia reveals that there is a large area of land that is unsuitable for crop production located close to all-weather roads in the less-favoured areas of the region. Few trees have been planted on this type of land up to now. The past policy seems to have discouraged tree planting except on homestead plots that are more suitable for food crops. This paper reports part of the IFPRI/ILRI project ‘Policies for Sustainable Land Management in the East African Highlands’. These two agencies have provided funds and logistical support for the work. The Norwegian Ministry of Foreign Affairs has provided funds for this research in the Amhara Region in Ethiopia. The authors also draw on earlier work funded by Research Council of Norway. Any correspondence should be directed to the first author.     

半固定沙地植苗造林治理模式

呼伦贝尔沙地扩展和危害日益严重,为了保护呼伦贝尔大草原,有效治理草原沙漠化土地,在呼伦贝尔沙地不同分布区、不同类型立地进行了3个试验区的沙地造林试验,结果表明:3个试验区造林成活率都很高,固沙效果明显;陈巴尔虎旗和新巴尔虎旗试验区因牲畜啃食和浇水不及时而致保存率偏低;鄂温克旗采取网围栏全封措施,而保存率较高;3个试验区都有天然樟子松和杨树分布。     

Composted shrub-prunings and other organic manures for smallholder farming systems in southern Rwanda

Organic manures are the primary source of crop nutrients in many African farming systems. The quantity of such materials that are available on farms and their quality are therefore important issues, especially in countries with limited land resources, such as Rwanda. In this study, different types of compost (including composted shrub-prunings) were compared with farmyard manure (FYM) and green manure (Calliandra calothyrsus) using beans (Phaseolus vulgaris) as test crops. The study confirmed the farmers’ general opinion that FYM has high manurial value for crop yields. Composts with P- and Ca-rich Tithonia diversifolia prunings were of similar quality as FYM or dung composts and had a higher fertilizer value than Calliandra ‘green manure’ (biomass transfer). However, the farmers’ perception of trees and shrubs as biomass and nutrient sources is still very low in Rwanda. This revised version was published online in August 2006 with corrections to the Cover Date.