从龙泉县实际谈木材综合利用问题

龙泉县是浙江省重点林区。全县有林地为387万亩,森林蓄积量有827万立方米,每年提供商品木材12万多立方米,占全省任务的四分之一,另有毛竹180万根左右。但是,由于木材综合利用水平低,大量的采伐、加工剩余物霉烂在山或付之一炬,造成森林资源的极大浪费。近几年来,采伐范围日趋狭窄,木材径级越来越小,采伐路程逐     

尽快改变我国主要林区森林集中过伐的被动局面

(一) 森林是国家的宝贵资源。它不仅能为国家提供建设用材和多种林副产品,更重要的森林是工农业生产和人民生活的天然屏障。它改善生态环境、保持水土、涵养水源、防风固沙、调节气候、净化空气等方面都具有独特的作用。世界上一些工业发达国家,宁肯进口木材也     

森林生态效益计量方法及存在的问题

森林生态效益是在大气环流和太阳辐射的作用下,森林通过物理和化学作用,对地球生物圈提供直接和间接的有利于人类生活质量提高的生态功能,主要包括涵养水源、防风固沙、调节气候、减轻噪音等生态功能,森林的这些生态功能在特定的时间和地点被人们利用所带来的收益.对森林而言,人们已经意识到森林既给社会提供以木材为主的林产品等物质产品,同时也能为社会提供良好的环境服务的非物质产品.     

森林的生态效益

复盖在地球陆地上22％的森林,是地球上最大的生态系。 森林在维持自然界的生态平衡中,有着举足轻重的作用。它不仅能为满足国家和人民日益增长的木材和林产品的需要,更重要的是它对涵养水源、净化大气、消除噪音、调节气候和维持自然界生态平衡起着相当重要的作用。森林的生态效益比它本身的木材价值要大好几倍,十几倍甚至几十倍之多。但对森林的社会功能的经济评价是个极其复杂的问题。我国     

防护林工程建设和生态效益评估

1林业政策和森林生态效益世界上许多国家通过深入研究，对森林所具有的多种功能和多种效益有了较全面的了解。确认森林生态效益的价值，已远远超过它提供木材、林副产品的经济效益价值。如芬兰现有森林2237万hm2，每年提供木材的价值为17亿马克，而在涵养水源、保持水土、保护环境等方面创造的价值为53亿马克，即1:3。美国科学家估算，美国森林的生态效益与经济效益的比值为9:1。在1960年时，美国公布的国有林“多种利用及永续收获”条例把木材生产排在游憩、放牧之后，为第三位。原西德1975年的“保持森林和发展林业法”提出的森林经营目标…     

印度尼西亚的森林资源核算

我们为印度尼西亚森林资源建立了初步的实物帐户和价格帐户。这些帐户的内容并不包括印度尼西亚森林资源的全部价值。例如,产自森林中各种重要的非木材商品,如藤子、油料、树脂、粮食和药物产品,以及森林所提供的重要生态效益均不包括在内。原则上说,森林中的非木材商品是国内生产总值的一部分,但实际上它们的价值往往被大大地低估了。1982年,印尼全国仅非木材产品的出口额就高达1.2亿美元。对毁林所造成损失的完整核算本来也应包括由于毁林而失去的森林非木材产品和生态效益的将来收益。     

建设城市林业生态初探

建设城市林业生态初探陈美高，黄奕炳森林是陆地生态系统的主体，是人类赖以生存的基础，它不仅为社会提供木材和各种林副产品，还具有调节气候、净化空气、保持水土、涵养水源、防风固沙等多种功能，也是农牧业稳定高产的生态屏障，更是人们休息娱乐、强身健体、森林旅游...     

大力发展木材综合利用是云南林业建设的当务之急

云南省的森林,自然条件比较优越,开发又较晚。因此,云南省的森林资源还算多一点。但是,随着木材和其它林产品的需求量与日俱增,云南省的木材供需矛盾同样也越来越突出。现在,越来越多的人认识到,森林不仅能提供木材和其它林产品,而且还具有调节气候、涵养水源、保持水土、防风固沙、净化空气、美化环境等作用。所以,必须十分爱惜森林资源,而大力发展木材综合利用是保护森林、发展林业、解决木材供需矛盾的重要途径,     

谈谈林木的商品性——1985年12月2日在林业经济讲座班的讲话

林业这几年在问题成堆的情况下,已逐步理出了头绪。林业问题在中国是一个极大的问题,它是经济问题,但又不是单纯的经济问题,而是一个与自然环境问题有密切关系的经济问题。因此,它引起人们的注意、引起党和政府的重视,就决不是偶然的。作为与自然环境关系十分密切的林业,经历了两个根本性的转化。第一,是从产品向商品的转化;第二,是从自然产物向人工产品的转化。森林,最初不是商品,作为自然生长物,在人类有商品交换之前,甚至人类存在之前,就已存在世界上。只是随着社会经济的发展,特别是交通运输的发展,大片天然森林才由自然存在物转化成社会商品。与此同时,木材的用途也日益广泛,使用量急剧增加,迫使它开始了自然产品向人工产品的转化。     

英国的城乡绿化

英国是一个美丽的岛国，坐落在欧洲西部茫茫的大西洋中，英国全国森林面积283万公顷，人均有森林0．04公顷，森林覆盖率11．6%。英国木材的自给率很低，年产木材700万立方米，仅占全国消耗量的15％，其余靠进口。英国森林的主要功能不是生产木材，而是提供环境服务和游憩。     

Changes in Brazil’s Forest Code can erode the potential of riparian buffers to supply watershed services

In Brazil, the Forest Code requires landholders to maintain fixed-width buffers of native vegetation along watercourses – legally called Areas of Permanent Preservation (APPs). In 2012, agricultural activities started to be partially allowed in APPs, but only if best management practices on soil and water conservation are adopted and if a narrow buffer strip with native vegetation is restored adjacently to the watercourse. In this paper, we present a modeling framework to investigate the capacity of legal compliant APPs to supply watershed services (erosion control and stream bank stabilization) in a 2,200 ha watershed in São Paulo State, Brazil. Our results suggest that the narrower the riparian buffer the lower the control of soil erosion dynamic within APPs, and that riparian buffers smaller than 8 m can act as a source of sediments to streams. The adoption of best management practices can contribute to controlling soil erosion within APPs but the presence of native forests in the first 15 m is necessary to guarantee equivalent protection to streams when compared to APPs completely covered by forests. Moreover, we observed that forest restoration within APPs helped to reduce the average soil loss of the watershed by only 20 %, compared to a reduction of 55 % when best practices are implemented in all watershed agricultural areas. We conclude that (i) the reduced requirements for APP restoration may contribute to stream sedimentation, which will likely affect the supply of watershed services by stream ecosystems; (ii) the implementation of best management practices in APPs will not have the same effect as native forests to reduce stream sedimentation; and (iii) the adoption of best management practices in all agricultural production areas – and not only within APPs as required by law – is the best strategy to promote the supply of watershed services to society.     

Optimizing joint production of timber and carbon sequestration of afforestation projects

Optimizing harvesting decisions has been a matter of concern in the forestry literature for centuries. However, in some tropical countries, growth models for fast-growing tree species have been developed only recently. Additionally, environmental services of forests gain importance and should be integrated in forest management decisions. We determine the impact of a joint production of timber and carbon sequestration on the optimal rotation of a fast-growing species in north-western Ecuador, comparing different optimization approaches and taking the latest developments of the Kyoto Protocol into account. We find that payments for carbon sequestration have substantial impact on the rotation length: in contrast to an optimum of 15 years when focusing on timber production only, joint production leads to a doubling of the rotation length, which means that timber harvest should be postponed until the end of the carbon project.     

集体林区林权制度改革对木材供给影响的实证分析

首先用probit模型对林农参与集体林区林权制度改革的激励因素进行了探讨,之后应用双重差分模型(DID)和处理效应(TE)方法深入分析了林权制度改革对木材供给行为的影响。研究结果证实,由于赋予林农更加完全和稳定的林地经营权和收益权,林权改革显著增加了木材的采伐量,对木材市场的供给起到了积极的促进作用,但对于改革前后产权制度变化不明显的竹林则不存在显著影响,同时提出要进一步分析林权改革给林农福利和森林资源带来的影响,还需更加长期的观察和研究。     

Editorial - Multiple-use forestry

The problem of multiple-use forestry arises because (1) a forest can be managed to provide a wide range of products and services, (2) the different uses are not perfectly compatible with each other, and (3) some products are not priced in markets and many of the services a forest provides have the characteristics of public goods. Examples of major forest products include, in addition to timber, edible berries, fungi, and hunting games. Forests also provide recreation opportunities and various environmental services (such as regulating local climate, reducing soil erosion, reducing pollutants in the atmosphere, regulating the global climate, providing habitats for wildlife, etc.). The outputs of nontimber goods in general depend on the quantity and structure of the forest, which can be changed by various forest management activities. However, a forest state most suitable for the production of one good is usually not optimal with respect to another good. Typically, there does not exist a set of management activities that simultaneously maximize the outputs of timber and all other goods.Another way to understand the conflicts between different uses is to view standing timber as an intermediate product of forestry investment, which is employed as an “input” for the production of timber products and nontimber goods. Thinking in this way, the conflicts arise partly because timber production and nontimber uses compete for the same input, and partly because of the differences in the “production technology” among different nontimber goods. A change in the standing timber may have positive impacts on some nontimber uses, but have negative effects on others. Because of the conflicts among different uses, it requires that both timber products and nontimber goods should be explicitly incorporated into forestry decision-making in order to achieve the greatest benefits to the forest owner and/or the public.Most of the economic analyses of multiple-use forestry decisions have explicitly or implicitly adopted the view that multiple-use should be achieved in individual stands. Each stand should be managed to produce an optimal mix of timber products and nontimber goods. Another view of multiple-use forestry is to manage each stand for a primary use, whereas multiple-use concerns are addressed by allocating different stands in a forest to different uses. A general argument in support of the primary-use view is that specialization makes for efficiency. The production of timber and nontimber goods is a joint process, however. Strictly speaking, one cannot separate timber production and the production of different nontimber goods. For example, managing a stand for timber production does not exclude the possibility of producing some nontimber goods in the stand. Since every stand usually produces more than one product, efficient multiple-use forestry requires that each stand should be managed for an optimal mix of timber and nontimber outputs. On the other hand, it may well be the case that the optimal multiple-use mix for a particular stand consists of a maximum output of one product. In this case the optimal multiple-use management decision would coincide with the optimal decision pertaining to a single use. In other words, it may be optimal to manage a particular stand for one primary use. Using the terminology of economics, primary-use may be efficient for stands in which the multiple-use production set is nonconvex. Recent research has explored several sources of nonconvexity in the multiple-use production set. However, there is no evidence supporting the argument that specialization is always more efficient than multiple-use management of individual stands. From an economics viewpoint, efficient primary-use is special cases of multiple-use stand management.A widely recognized limitation of multiple-use stand management is that, by considering each stand separately, one neglects the interdependence of nontimber benefits and ecological interactions among individual stands. The nontimber benefits of a stand depend on the output of nontimber goods from other stands. Likewise, the nontimber output from one stand affects the value of nontimber goods produced in the other stands. Ecological interactions among individual stands imply that the output of nontimber goods from two stands in a forest differs from the sum of the outputs from two isolated stands. These interdependence and interactions imply that the relationship between the nontimber benefits of a stand and the stand age (or standing timber stock) cannot be unambiguously determined - it depends on the flow of nontimber goods produced in the surrounding stands. Therefore, it is improper to determine optimal decisions for the individual stands independently. In stead, efficient multiple-use forestry decision should be analyzed by considering all the stands in a forest simultaneously.Another serious limitation of multiple-use stand management is that each stand is treated as a homogenous management unit to be managed according to a uniform management regime. One implicitly assumes that the boundaries of each stand is exogenously given and will remain unchanged over time. This assumption imposes a restriction on the multiple-use production set, thereby creates inefficiency. As an example, consider a large stand with a nonconvex production set. It may be possible to eliminate nonconvexity in the production set and push the production possibility frontier outwards by dividing the stand into several parts and managing each part for a primary-use. It may also be efficient to combine two adjacent stands into one to be managed following a uniform regime, because of the presences of fixed management costs, and/or because the relationship between some nontimber outputs and stand area is not linear.In contrast to income from timber production, nontimber goods produced at different time points are not perfect substitutes. The rate at which a forest owner is willing to substitute a nontimber good produced at one time point for that produced at another time point changes with the outputs of the nontimber good at the two time points. In general cases, the nontimber goods produced at one time point cannot be consumed at another time point, and the marginal utility of a nontimber good decreases when its output increases. This provides a motivation for reducing the variation in the output of nontimber goods over time. An effective approach to coordinating nontimber outputs over time is to apply different management regimes to different parts of a stand, or apply the same regime to adjacent stands, which would change the boundaries of the stands. Preserving the existing stand boundaries would limit the possibility of evening out the nontimber outputs over time, and thereby lead to intertemporal inefficiency in multiple-use management.In previous studies of multiple-use forestry decisions the nontimber outputs or benefits are usually modeled as functions of stand age or standing timber stock. Future flows of nontimber goods or benefits are incorporated into a stand/forest harvest decision model to explore the implications of nontimber uses for optimal harvest decisions. While stand age and standing timber stock may have significant impacts on nontimber outputs, other forest state variables, e. g. the spatial distribution of stands of different ages/species, may be of great importance to the production of nontimber goods. Recognition of such forest state variables could change the relationship between timber production and nontimber outputs and therefore change the optimal forest management decisions.In summary, multiple-use forestry is not simply an extension of timber management with additional flows of benefits to be considered when evaluating alternative management regimes. Recognition of multiple uses of a forest leads to two fundamental changes of the forestry decision problem. First, the optimal intertemporal consumption of forestry income is no longer separable from forest management decisions. In general, the optimal intertemporal consumption of forestry income depends on future flows of nontimber goods, implying that the consumption-saving decision should be made simultaneously with the decision on the production of timber and nontimber goods over time. Secondly, it is no longer appropriate to optimize the management regime for each stand separately. The nontimber outputs from a forest depend on the age distribution of individual stands, and on a wide range of other forest state variables such as the spatial distribution of stands of different ages and tree-species composition. Ecological interactions and interdependence among stands imply that management regimes for different stands should be optimized simultaneously. In addition to changing rotation ages and harvest levels, efficient multiple-use forestry requires optimizing the spatial allocation of harvests, redefining the boundaries of stands, coordinating the choices of tree species in regeneration of harvested area and so on.The lack of rigorous production functions for nontimber goods imposes a severe restriction on attempts to perform comprehensive economic analyses of multiple-use forestry decisions. This restriction in itself is no justification for ignoring many of the key aspects of multiple-use forestry problem and modeling the problem as one of determining the optimal rotation age or optimal harvest level. It requires that economic models of multiple-use forestry should be developed with special consideration of the vague and imprecise information regarding the relationships between nontimber outputs and forest state variables.Peichen GongDepartment of Forest EconomicsSE-90183 UmeåSweden     

Harvesting Choices and Timber Supply among Landowners in the Southern United States

The recent rise of institutional timberland ownership has led to a significant change in the structure and conduct of the timber industry in the United States. In this study, we apply a two‐period harvest model to assess the timber harvesting behavior of various landowners at the stand level by utilizing USDA Forest Service Forest Inventory and Analysis data for nine southern states. Forest industry and institutional timberland owners were found to be more likely to conduct partial and final harvests than nonindustrial private forest landowners. Aggregately, Timberland Investment Management Organizations were found to be most, and timberland Real Estate Investment Trusts to be least, price‐responsive among ownership groups.     

社会化服务对农户林地规模经营行为的影响研究

以林业栽培技术服务为例,基于1342份实地调研数据运用IVProbit和倾向得分匹配(PSM)模型考察林业社会化服务对林地规模经营行为影响的程度和方向。结果表明:林业栽培技术服务能显著促进农户林地规模经营行为,但对不同林种的影响程度差异较大;林业工作站或技术推广站主导的栽培技术服务在促进农户规模化经营行为中承担主要角色,反映出林业社会化服务的市场化进程相对缓慢,市场化主体供应的服务未能很好地满足农户林地规模化经营的需求。因此,政府应当大力发展林业社会化服务,完善林业生产服务体系,扩大服务的受众面;培育多元化社会化服务主体,推动林业社会化服务专业化和精准化发展。     

Consequences of carbon offset payments for the global forest sector

Long-term effects of policies to induce carbon storage in forests were projected with the Global Forest Products Model. Offset payments for carbon sequestered in forest biomass of $15–$50/t CO₂e applied in all countries increased CO₂ sequestration in world forests by 5–14 billion tons from 2009 to 2030. Limiting implementation to developed countries exported environmental damage from North to South, as developing countries harvested more, decreasing their stored CO₂e. Substantially more CO₂e was sequestered by allocating a given budget to all countries rather than to developed countries only. As offset payments increased wood prices relatively more than they decreased production, timber revenues generally increased. In the few countries with timber revenues losses they were more than compensated by the offset payments.     

中国西北干旱地区湿地生态系统的形成、演变和保护对策

在我国西北干旱地区，一些内陆湖泊湿地生态系统滋养了西北地区的历史文明和繁荣，从多方面支持了当地人民生活、全球生态系统的稳定和生物多样性，对保护干旱地区生态环境和促进干旱区域可持续发展具有重要意义；分析了西北干旱地区湿地生态系统的类型、形成过程及人类活动的影响，从区域可持续发展、流域水资源的合理利用、生态用水的保证、湿地生态系统服务功能的维持等方面，提出了西北干旱地区湿地生态系统的管理目标和保护对策。     

论以林地资源管理为中心创新森林资源管理制度

森林资源包括森林生物资源、林地资源和森林环境资源,但林地资源是基础。森林资源管理必须以林地资源管理为中心。由于公益性森林资源作为公共物品其经营的主导利用目标是生态效益。因此,林政资源的管理要以林地资源管理为基础,林木与林地管理并重,严格森林资源的保护。而商品性森林资源经营的主导目标在于经营利润的最大化,应赋予经营者更灵活的处置林木的权力,资源管理以林地资源管理为主。     

Urbanization as a land use change driver of forest ecosystem services

Land use change in the form of urbanization is a direct driver affecting the provision of ecosystem services from forests. To better understand this driver, we modeled the effects of urbanization on three regulating and provisioning ecosystem services in two disparate watersheds in Florida, USA. The study integrated available geospatial and plot-level forest inventory data to assess future changes in carbon storage, timber volume and water yield during a period of 57 years. A 2003–2060 urbanization and land use change scenario was developed using land cover data and a population distribution model. The Integrated Valuation and Ecosystem Services Tradeoffs model was then used to quantify changes in ecosystem services. Carbon storage was reduced by 16% and 26% in the urbanized 2060 scenario in both the rural Lower Suwannee and urban Pensacola Bay watersheds, respectively. Timber volume was reduced by 11% in the Lower Suwannee and 21% in the Pensacola Bay watershed. Water yield, however, increased in both watersheds by 4%. Specific sub-watersheds that were most susceptible to urbanization were identified and mapped and ecosystem service interactions, or trade-offs and synergies, are discussed. Findings reveal how urbanization drives the spatio-temporal dynamics of ecosystem services and their trade-offs. This study provides policy makers and planners an approach to better develop integrated modeling scenarios as well as designing mapping and monitoring protocols for land use change and ecosystem service assessments.