生长量和伐期龄、采伐量的关系

<正> 用材林的生长量(本文指的是用材林的材积生长量,下同)和伐期龄、采伐量有着十分密切的关系。森林经理学告诉我们,“当森林在生长发育过程中达到最符合经营目的和任务的状态,称为森林成熟”,而用材林的成熟期主要根据木材生长量确定。森林生长量又是确定森林采伐量的主要依据之一。森林经理学和我国的《森林法》以及历来的森林经理     

森林经营单位合理年采伐量分析研究

森林采伐是调整森林结构、改善森林质量、提高森林功能的关键措施。科学的采伐管理是实现森林可持续经营的重要途径。当前我国森林采伐实行采伐限额管理制度,森林经营单位的年采伐限额原则上按森林经营方案确定的合理年采伐量核定。因此测算和确定合理年采伐量是经营方案编制的重要内容。以吉林省红石林业局为研究区,对森林经营单位如何科学测算和确定合理年伐量进行深入分析研究,以期在技术和方法上为森林经营单位编制森林经营方案及测算合理年采伐量提供参考。     

“十一五”期间森林合理年采伐量测算及存在问题的探讨

介绍了“十一五”期间森林合理年采伐量测算的原则、采伐类型、测算方法、测算数据与测算参数,探讨了合理年采伐量测算工作中存在的问题,对进一步完善合理年采伐量测算方法、优化测算软件提出了意见与建议。     

关帝林局合理年采伐量测算论证分析

关帝林局森林合理年采伐量测算,遵循年采伐量小于年生长量的原则,首先根据林局的资源现状,进行了年生产量测算,然后对年采伐量的测算进行了详细的分析论证,最后得出所确定的年伐量是科学合理的结果。     

森林可持续采伐量测算的几个问题

六大重点林业工程实施以后,原有的森林采伐量测算方法需要进行修改和完善。本文讨论了森林可持续采伐量测算中需要考虑的几个问题,并就改进森林可持续采伐量测算工作提出了几点建议。     

辽宁省“十四五”森林合理年采伐量测算方法

文章结合森林合理年伐量测算系统,使用Python编写程序,实现从测算数据小班表到测算结果的自动、批量处理方法,完成森林合理年采伐量测算数据的一键提取,提高森林合理年采伐量测算的效率。     

刍议不同林种合理年伐量的确定

合理确定森林年伐量是保护和发展森林资源的重要环节。确定和论证森林采伐量与森林的国民经济意义有密切关系。不同国民经济意义的森林具有不同的森林利用制度。所以森林经理在确定年伐量时,应根据所划分的林种加以分析论证。以下分别按用材林、防护林和薪炭林说明年伐量确定的原则。     

采伐限额编制中合理年采伐量的确定

文章论述了在辽宁省＂十二·五＂期间年森林采伐限额的编制中,采用面积控制法和材积控制法对年采伐量进行测算,确定＂十二.五＂期间合理年采伐量,对采伐限额的编制具有现实的指导意义。     

关于核定采伐限额的几点浅见

森林采伐限额是确保森林资源“青山常在,永续利用”的一项强有力措施。而合理地确定采伐限额,是能否充分保护,科学利用森林资源,发挥采伐限额作用的关键性问题。我想就此谈一点浅见。 一、关于合理采伐量的确定 采伐限额能否见效,在技术上取决于合理采伐量的正确与否。从林种上看包括用材林、防护林、特用林及疏林合理年伐量的确定。     

人工用材林资产评估的实践与探索

人工用材林是森林资产的最重要的部分，人工用材林资产的评估是用材林资产评估的基础，本文根据福建省光泽县华桥乡林场部分人工用材林资产的评估实践，探讨了林地地租，幼龄林，中近成熟林评估的各种测算方法，并对各测算结果进行分析，比较，提出了在幼龄林和中成熟林中较为合理的森林资产测算方法。     

The impact of community-based forest management on timber treeregeneration in north-eastern Honduras,with specific reference tobig-leaf mahogany (Swietenia macrophylla)

Reduced-impact logging is used to minimise the negative effects of selective logging. However, it has been suggested that low-impact logging may create too little disturbance for the regeneration of the light-demanding timber tree species, hence compromising forest productivity. This study evaluates the impact of low-intensity, non-mechanised, certified community forest management on timber tree regeneration. Particular attention was paid to big-leaf mahogany (Swietenia macrophylla), which has a regeneration pattern linked with large-scale disturbances. Logging gaps were compared to natural treefall gaps of an unlogged forest. There were more species of the light-demanding timber trees, but fewer individuals of the shade-tolerant timber species in the certified forest logging gaps, compared to unlogged forest treefall gaps. Furthermore, significant differences were found in the environmental characteristics of the logging and natural treefall gaps, although these only partially explained the differences in timber regeneration. Mahogany was found in over half of the logged forest gaps, whilst being nearly absent in the natural treefall gaps. However, all mahoganies in the established logging gaps were seedling-sized, indicating that regeneration may be hampered due to competing vegetation. The results of the study suggest that low-impact forest management may, at least in the short term, favour light-demanding species over the shade-tolerant ones, similarly to conventional forest management.     

Long-term ecological impacts of clear-fell logging on tree species diversity in a subtropical forest,southern Japan

Defining the spatial arrangement and length of the cutting cycle in a logged area is crucial for reconciling potential conflicts between timber yields and maintenance of ecosystem services in natural forests. In this study, we investigated long-term impacts of clear-fell logging on timber production and tree species diversity in a subtropical forest on the Ryukyu Islands, using an individual-based simulation model. We assumed six logging scenarios defined by combinations of forest type and regeneration processes, which acted as surrogates for spatial scales of clear-fell logging. These scenarios were simulated under cutting cycles ranging from 20 to 150 years. Short-cutting cycles resulted in dominance by the sprouting species Castanopsis sieboldii. The compositional shift was accelerated by the lack of seed dispersal from surrounding forest areas. The simulations demonstrated that a sustainable logging regime maintaining both yield and tree species diversity requires a cutting cycle longer than 50 years. The simulation results also suggest that the trade-off between the recovery of tree species diversity and timber production is favored more in stands surrounded by mature forest than in isolated stands or stands surrounded by immature forest. Ecological risk assessments based on model simulations provide an alternative to current forest management practices that rely on empirical knowledge.     

打击木材非法采伐的森林执法管理与贸易国际进程

探讨了世界森林执法管理与贸易国际进程现状, 分析了森林执法管理与贸易进程和打击木材非法采伐存在的主要问题, 并提出推进国际森林公约、参与跨国联合行动、提高木材供给国执法能力、加强消费国木材监管体系建设、重视非政府组织意见、加强行业信用评价、积极开展森林认证和引导消费者的态度等加强森林执法管理与控制木材非法贸易的对策建议。     

Damage to Brazil nut trees (Bertholletia excelsa) during selective timber harvesting in Northern Bolivia

The success of multiple forest management systems is contingent on a variety of social, economic, biophysical, and institutional factors, including the integration of timber and non-timber forest product (NTFP) extraction and management. Selective logging for timber is increasingly taking place in forests where the collection of Brazil nuts, a high-value Amazonian NTFP, also occurs. We report on logging damage to Brazil nut trees in three certified timber concessions in Northern Bolivia from which timber is harvested using reduced-impact logging (RIL) guidelines and nuts are gathered yearly from the ground by local people. Observed frequencies of logging damage to Brazil nut trees were low, likely mirroring the low intensity of timber harvesting (∼0.5 trees/ha and ∼5 m³/ha) being currently applied across the study area. Of the trees ≥10 cm in diameter at breast height about 0.1 Brazil nut trees and 0.4 timber species per hectare suffered some degree of logging damage. Crown loss was the predominant damage type for Brazil nut trees accounting for 50% of all damage. In spite of the observed low rates of tree damage, we further recommend that RIL guidelines be amended to include the pre-harvest marking of pre-reproductive Brazil nut trees along with the future crop trees of commercial timber species. Further refining directional felling to reduce crown damage to Brazil nut trees would also serve to help maintain nut yields in the long term.     

Estimating harvest costs and projecting quantities of logging residues for small-scale forestry in Nasushiobara,Tochigi Prefecture,Japan

We used GIS on a regional scale to estimate and compare supply potentials and costs of small-scale logging systems, a mini-forwarder and a 4-ton truck operated by private logging contractors, and manual logging and a light truck operated by individual forest own- ers, with the mechanized operational system of the Forest Owners＇ Asso- ciation. Total potential yields of timber and logging residues were esti- mated as 418,895 m3 and 254,962 m3, respectively. The economic bal- ances were estimated and available amounts were projected as supply potentials from profitable sub-compartments. As a result, available amounts of timber and logging residues were estimated at 375,466 m3 （89.9%） and 203,850 m3 （80.0%）, respectively. Because their transport expenses were lower than for other systems the most profitable sub-compartments were operated by private logging contractors who sold logging residues at a plant. The profitable sub-compartments operated by individual forest owners were few because the extracting distances were usually greater than 20 m. Raising logging residue prices from 3,000 yen·m-3 to 4,080 yen·m-3 or 6,800 yen·m-3, and establishing forest roads, which reduced some extracting distances to less than 20 m, increased the number and area of profitable sub＊compartments, and increased available amounts of logging residues.     

Why stumpage prices differ between ownerships: A statistical examination of state and forest service sales in montana

Broad differences in prices exist between national forest timber and that sold by other public agencies in the western U.S. Using state vs. national forest timber sale data from Montana, the author makes a statistical inquiry into the sources of these price differences and reaches several important conclusions. National forest timber sells for a lower price than state timber because large national forest sales command much lower prices than small national forest sales and, therefore, draw down the average national forest timber price. In general, the larger national forest sales are associated with higher sale development costs and utilize more costly logging systems. More prudent national forest sale planning and development could increase national forest timber receipts substantially and aid in solving one of the national forest system's more perplexing policy dilemmas—below-cost sales.     

云南省“十二五”森林采伐限额执行情况研究

分析“十二五”森林采伐限额的政策特点，指出森林采伐限额执行中县级采伐管理制度不健全、采伐管理人员素质低，森林采伐限额及木材生产计划分配不合理，作业设计不规范、质量不高，林木采伐（移植）许可证办理不规范等问题，并对存在问题进行了原因分析。提出加强政策学习，完善规章制度，科学分配指标，严格公示制度，加强人员培训，提高设计质量，加强伐区监管等对策与建议。     

Estimating costs of salvage logging for large-scale burned forest lands: A case study on Turkey's Mediterranean coast

Different forest fires causing different degrees of effects occur in fire-sensitive forests due to various reasons such as climate change.Useful as well as harmful aspects of forest fires are a multi-disciplinary research topic.Geographical information systems(GIS) and remote sensing(RS) methods offer a number of benefits for researchers and operators in the field of forest fire research.The present study analyses timber pricing based on forest contractor demands of post-salvage logging processes.The effect of timber obtained from compartment units on producers' pricing policy was modelled.Sapadere forest fire area(2500 ha)located in Antalya in Turkey was selected as the main study area.Topography parameters(aspect,slope and slope position),stand types(diameter class and crown closure),and burn severity were analyzed together using GIS and R software packages.A multi-linear regression model(R~2=0.752)demonstrated that factors that had the most impact on pricing were slope position,aspect,stand age,crown closure and burn severity.This model can be used to estimate salvage logging prices in Calabrian pine(Pinus brutia Ten.) stands with similar parameters.Forest administrators and contractors may readily address the unit price of timber by estimating approximate costs in a given forest area for which they are going to bid.This will help reduce operational planning times of harvesting procedures in burned stands.     

印度尼西亚森林警察打击非法采伐的执法对策及存在问题分析

木材生产国的森林警察在打击非法采伐方面起到了十分重要的作用。文中首先简要介绍印度尼西亚的森林警察制度,以Gunung Palung国家公园和吉打邦为例总结森林警察面对非法采伐的执法对策,对其抑制非法采伐的效果进行分析,指出印度尼西亚现行森林警察制度在打击非法采伐方面存在的问题主要包括执法权限受限、地方分权造成地方政府对于林地管理部门的忽视以及经济奖励制度存在缺陷。     

“四定四禁止”是云南烧材限额管理的一种好形式——禄丰县烧柴限额管理的启示

“八五”、“九五”期间云南全省烧材限额分别占总限额的55%和56%,而实际烧材还不止这个数字。“十五”期间烧材限额占59.1%,因此形势非常严峻,为探索新形势下烧材管理的有效办法,通过对楚雄州禄丰县的调查,认为对烧材实行“四定”和“四禁止”是一个好办法。“四定”县“定采伐数量、定代伐地点、定采伐时间、定采伐树种”。“四禁止”是“禁止挖树根、禁止砍伐水源林及特殊地带的林木、禁止在公益林带及稀疏林内砍伐林木、禁止砍伐用材林”。此外还有相应的配套措施。