闽北用材林林地标准地租的确定

以福建省北部为研究对象,收集杉木成过熟林小班1 342个,选取小班154个,采用林地期望价法计算各小班的地租,根据立地质量等级不同,用各地类中地租最大值与该地类平均地租的比值,确定闽北用材林林地标准地租基于平均地租的上浮比例。结果表明:闽北用材林林地的标准地租是基于平均地租上浮30%基础上确定的。     

基于林地类型的基准地价评估方法与应用研究

评估林地基准地价,为林地流转提供参考价格,有利于规范林地使用权交易。基于海南省五指山市林地定级数据,以外业调查样点林地价格为因变量,样点所在定级单元的定级指数为自变量,分地类建立定级指数模型,利用模型计算所有定级单元的林地价格,同一级别的所有林地定级单元价格平均值即为对应级别的基准地价。结果表明,研究区域林地基准地价与林地级别相对应,从1级到5级呈递减趋势,以芒果和荔枝为代表的乔木经济林地基准地价最高,以茶树为代表的灌木经济林地次之,竹林地、短轮伐期用材林地、一般用材林地、一般灌木林地的基准地价依次递减。经济林地价格远高于用材林地,且同一类型的林地价格因树种不同而差异巨大。各级别林地基准地价反映了不同质量林地的价格水平,可以为林地流转提供参考价格,有利于盘活林业资源,推进森林有偿使用,为自然资源保护和合理开发利用提供支撑。     

林地质量评价技术方法探讨——以重庆市城口县为例

林地质量评价是林地管理的重要内容,以重庆市城口县作为评价样本,以城口县森林资源规划设计调查数据为基础,选择分布比较广泛的马尾松作为标准树种,在计算马尾松小班的立地指数的基础上,回归计算所有林地小班立地指数,作为所有林地小班的地力指数,以小班单位面积蓄积量作为生产力指数,小班的交通距离作为区位指数,综合计算各林地小班的林地质量得分,从而对所有林地小班的林地质量进行分等定级,完成城口县的林地质量评价。评价结果:城口县林地质量等级分为5级,其中:一等地面积占5.5%,二等地面积占40.1%,三等地面积占39.1%,四等地面积占13.6%,五等地面积占1.7%。以此可以制定城口县的林地差别化管理政策,实行与城口县林地质量等级相对应的森林经营模式和利用方式。     

林地质量等级及快速评定

林地是森林资源的载体和林业发展的基础,林地质量分级是林地质量评价的重要指标。结合我省县级林地保护利用规划,选取林地土层厚度、土壤类型、坡度、坡向、坡位和交通区位等6项因子,以林地小班为单位,采用层次分析法,利用电子表格编制公式,快速计算其分值,确定各林地小班的质量等级,为林地保护利用规划和林地资源管理提供科学依据。     

用材林林地分等技术研究

在构建福建省用材林林地等级评价指标体系(自然因素、森林资源因素和社会经济因素3大类15个指标)的基础上,采用灰色系统理论中的灰色关联度确定各评价指标的权重,以福建省县级行政区为评价单元计算总分值,采用聚类分析法划分等级,将全省各县(市、市辖区)划分为3个等级,旨在为林权制度深化改革,全面建立健全现代林业体制、机制,合理开发、利用和保护林地服务。     

基于GIS的射洪县林地质量等级评价研究

林地是森林资源的载体和林业发展的基础,林地质量分级是林地质量分析与评价的重要指标。结合四川省射洪县林地保护利用规划,本文选用土壤厚度、土壤类型、坡度、坡向、坡位和交通区位等6项因子建立评价指标体系,采用层次分析法,以林地落界小班为单位,结合GIS空间分析方法,确定各小班的林地质量等级,并将林地划分为5个等级,Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ等级的林地面积分别为0、44.22 hm2、5 437.46 hm2、41 089.05 hm2、76.36 hm2,分别占林地总面积的0、0.09%、11.66%、88.08%、0.16%,该研究对林地保护利用和林地资源依法、科学、合理、统一管理具有重要的意义。     

金坝林场人工用材林地、林木价值量初步估算

富宁县国有金坝林场面积10 109hm2,其中人工用材林5 410.7hm2,林木蓄积616 900m3,分别采用林地期望价法、重置成本法、收获现值法、木材市场倒算法等对该林场人工用材林地及林木资产进行了估算.估算结果,林地地价1 952.23万元,林木价值为6 867.60万元.     

林地定级及基准价的研究与应用——以浙江省龙泉市为例

【目的】对林地进行合理定级并制定林地基准价,为解决林地资源资产评估核算困难的问题,提高大批量林地价值评估效率提供参考。【方法】基于浙江省龙泉市2016年森林资源规划设计调查数据,林地定级运用因素法,首先选取自然因素、社会经济因素以及区位因素,利用熵值法确定各个因素指标权重,加权求和模型计算定级指数,最终采用总分数轴确定法对林地定级;林地基准价通过林地期望价法计算确定。【结果】1)研究区林地资源分为4个等级,小班个数及总面积从1级到4级先上升后逐渐减少,林地等级呈正态分布形式,结构合理;2)研究区林地基准价从1级到4级分别为10 504、8 978、7 631和6 284元·hm^-2,各等级林地基准价的高低反映林地质量的优劣程度;3)根据林地的特殊性,结合林地生产力水平的外在体现,制定出与林地基准价相匹配的价格修正系数;4)结合林地基准价与价格修正系数核算研究区林地资源资产经济总价值为2 456百万元。【结论】各等级林地分布特征表明林地定级结果符合林地质量与林地价值差异特征,利用林地基准价进行研究区林地资源资产经济价值核算具有较高适用性,研究成果可为大批量林地资源价...     

林地分等定级技术体系框架探讨

林地的科学分等定级对促进林地资源优化配置、强化林地管理具有十分重要的现实意义,是深化林权制度改革的重要途径。在吸取当前我国森林立地评价的相关成就基础上,构建了林地分等定级技术体系。通过林地“分等”和“定级”两个层次工作,对影响林地质量的经济、社会、自然因素各项因子综合分析,按立地类型进行立地质量分析和适宜性评价,确定林地自然质量等;根据区域土地利用和社会经济水平调查结果,确定林地综合指数;充分体现其使用价值,以期为今后林地估价工作奠定基础。     

林地分等定级模式构建与实践——以海南省林地为例

以海南省林地资源为例,开展基于《自然资源分等定级通则》的实践研究工作。创建了不能直接获取数据的分等定级指标解译模型,利用因素法及修正法,构建了海南省林地分定等级的评价方案,明确采用五等五级评价系统。结果表明：海南省国土三调阶段性成果林地1 824.74万hm²,林地分等定级基本单元212.52万个图斑,每个图斑一等一级。实际存在1—4等4个等别;商品林林地788.09万hm²,实际存在1—5级5个级别;公益林林地1 036.65万hm²,实际存在1—5级5个级别。评价结果较好地反映出海南林地实际情况,可为全国林地分等定级工作的规范化、程序化及促进林地资源保护与合理开发利用提供参考。     

Analysis of determination methods for characteristic timber properties as related to growth area and grade yield

The origin of the raw material is a key aspect for strength grading of timber. Large grading areas are favored by the sawmilling industry as they require less effort in handling and documentation during the production process. However, large growth areas can also cause problems, as too high mechanical properties can be declared or yields may become uneconomical. The presented study presents a method that should allow for timber from different countries to be combined into a single grading area. Additionally, the influence on the yield for guaranteeing timber properties for differently defined populations is analysed. In this process, a number of available calculation methods for characteristic values for modulus of rupture, modulus of elasticity, and density are considered as the determination method also influences the final yield. Non-destructive and destructive test data from 8487 spruce specimens from Europe tested in bending or tension are the basis for the presented study. Based on the grading results the presented method is able to simply identify countries that may be combined. The definition of pan-European grading areas seems problematic if characteristic timber properties need to be guaranteed separately for each individual country as it may result in a severe drop in yield. However, checking timber properties only for the European population is unsatisfying as calculated timber properties considerably vary depending on the origin. As for the calculation method, the preferred method itself seems to have less impact on bending class assignments then on tension class assignments.     

独龙江流域森林资源现状及特点

根据森林资源规划设计调查方法,将独龙江流域进行单独区划,衔接县级林地保护利用规划及公益林生态效益补偿实施方案修编成果,得到了独龙江流域的森林资源现状。分析认为,独龙江流域具有林地比例高,人均林地面积多;森林覆盖率高,林地利用充分;乔木林每公顷蓄积量大,森林质量高;生态区位重要,公益林比例和林地保护等级高;天然林比重大,近成过熟林比例高;原始林多,植被保护好等特点。提出分级保护、发展林下经济、开展森林生态旅游、禁止木材运出等保护及开发利用建议。     

影响南平市木材价格主要因子的分析研究

本研究遵循资料易于获取的原则，从统计年鉴中选取可能影响木材价格的因素，采用主成分分析法和逐步回归分析法进行分析。研究结果表明：影响木材价格的主要因素，即亩蓄积、林地利用率、人均林业总产值和当地物价指数。     

贵港市港南区林地质量等级评定方法探讨

为了研究林地立地条件对当地主要树种的影响,在广西贵港市港南区范围内对林地小班逐个进行质量分等评定,港南区林地总面积为35989.5hm2,其中,Ⅰ级林地面积683.8 hm2,Ⅱ级林地面积7441.9 hm2,Ⅲ级林地面积27180.4 hm2,Ⅳ级林地面积600.3 hm2,Ⅴ林地面积83.1 hm2。文章分析了林地质量各个等级的空间分布,得出了坡度、石砾含量、土层厚度等的反应强度系数呈现出规律性变化,为今后林地小班选择造林树种提供了依据。     

Mechanical stress grading of tropical timbers without regard to species

Some reports have shown that for single species the correlation between modulus of elasticity (MOE) and modulus of rupture (MOR) in bending is quite high. Tropical timbers consist of hundreds of species that are difficult to identify. This report deals with the mechanical stress grading of tropical timber regardless of species. Nine timber species or groups of species with a total number of 1094 pieces measuring 60 × 120 × 3000 mm, were tested in static bending. The MOE was measured flat wise, while MOR was tested edge wise. Statistical analysis of linear regression with a dummy model and analysis of covariance were used to analyze the role of MOE and the effect of species on prediction of MOR. The analysis showed that using MOE as a single predictor caused under/overestimation for one or more species and/or groups of species. The accuracy of prediction would be increased with species identification. An allowable stress and reference resistance for species and/or groups of species were provided to compare with the prediction of strength through timber grading. The timber strength class for species and/or groups of species was also established to support the application of mechanical timber grading.     

Application of modal-based damage-detection method to locate and evaluate damage in timber beams

Modal-based damage-detection algorithms were used to identify the location of defects commonly found in timber and to estimate their severities. In this study, the authors propose modifications to an existing damage-detection algorithm for locating and evaluating damage by comparing the modal strain energy before and after damage using the first two flexural modes of vibration. Experimental verification was performed on pin-pin supported timber beams by employing the algorithms with extracted modal parameters using experimental modal analysis. Single and multiple cases of damage used to simulate pocket(s) of rot with various severities were inflicted by removing sections of timber beam specimens. The proposed damage indicator, computed from the first two flexural modes, was capable of detecting all damage locations. It was also able to estimate, with reasonable accuracy, the severity of damage in term of loss of sectional moment of inertia. The modified damage index method is generally reliable in detecting the location and estimating the severity of simulated defects in timber beams.     

半干旱农牧交错区人工林退化:概化模型和现状评价

在干旱半干旱地区,造林通常被作为荒漠化防治最为有效的措施之一,然而这一区域人工林退化也是不可回避的事实。本文以半干旱农牧交错区的内蒙古伊金霍洛旗为例,对其林地退化状况进行评价。根据野外调查结果我们建立了一个林地退化概化模型,据此筛选出湿润指数、植被指数、土壤类型和土壤侵蚀模数4个评价指标,并采用GIS对该区人工林退化状况进行评价。结果表明,在336.09km2人工林中,退化面积达311.35km2,其中轻度、中度和重度退化面积分别为78.97,119.73和112.65km2。退化人工林的防治重点应放在现有林的改良和造林植物种特别是灌木种的选择上。图4参15。     

基于LDI方法的新济洲国家湿地公园生态健康评价

采用遥感影像分析结合实地调查,对新济洲国家湿地公园的土地利用类型进行了分析,基于LDI方法对该湿地公园的生态系统健康状况进行了评价.结果表明:湿地公园有草地、天然草地、林地、农田、空地、水域、道路及建筑八种土地利用类型.其中,面积最大的土地利用类型是林地,占总面积的39.61％,在各个岛屿都有分布;退耕的农田面积比例为...     

The potential for developing a normal age-structure in managed ancient woodland at a local scale in three English counties

This paper describes a model for assessing the potential forsustained management of ancient woodland at the local landscapescale, based on the premise that a ‘normal’ foreststructure is the best option for integrating nature conservationwith provision of a regular supply of timber. The concept of‘normality’ is applied to clusters of small ancientwoods which are considered together and treated as a whole. Data on ancient woodland distribution are used from West Sussex,Essex and North Yorkshire. At ten sample points within eachcounty the woodland area within a 25-km² block centred on thepoint was considered to see whether a normal forest structurecould be created and maintained by sustained management usinglikely minimum felling rates and average rotation lengths forthe main species for both high forest and coppice systems. Themodel was also tested for situations where small woods or woodswith conservation status were excluded from the system, as wellas for different minimum felling rates. The areas proposed forfelling within ancient semi-natural woods currently listed withinthe Woodland Grant Scheme (WGS) (II) are higher than can bemaintained in the longer term in West Sussex and Essex. The model provides a preliminary method for setting the contextof individual forestry schemes withn the wooded landscape asa whole.     

基于神经网络和颜色特征对木材进行分级的分析

为了解决木材的分级问题，提出了利用神经网络和木材表面颜色特征对木材进行分级的方法。利用竞争神经网络对114种不同树种进行粗分，然后再用BP神经网络算法对此进行验证，又对四种木材进行分类验证。从计算机分类分级仿真效果上看，达到了预期的目的。