森林资源核算及其纳入国民经济核算体系的研究

一、前言目前,无论是就全球范围而言还是从我国的情况来看,森林资源都面临着很严峻的形势,森林资源和其它自然资源的衰退以及环境的恶化,导致了一系列严重的后果。从经济方面来看,如果把经济增长建立在不断开采和利用自然资源的基础之上,而忽视了对这些有限资源的维护,那么这种经济繁荣是不可能持久的,自然资源枯竭之日,也就是经济衰退之时;从环境方面来看,无节制掠夺式地开发利用自然资源必将伴随着生态系统不断地和不可逆转的改变,环境恶化将使得经济增长给人类带来的有限好处不足以弥补环境破坏所造成的损失。因此,近年来国际社会的有识之士一直在呼吁建立一个经济、社会、资源和环境持     

自然保护区管理现状与发展探索

设立自然保护区是保护自然资源,维持生物多样性,保持水土,降低自然灾害最有效的手段。自然保护区有着丰富的自然资源和生物资源,落实自然保护区的管理工作对于维持生物多样性,保护生态平衡具有至关重要的作用。如何管理自然保护区直接关系到我国的环境安全和生态安全。该文论述了我国自然保护区的管理现状,并提出相应的发展战略,以期全面提高管理效果,从而实现自然保护区的可持续发展。     

环境审计相关问题研究——以中冶美利云公司为例

指出了工业企业"先污染,后治理"的粗犷型经济发展方式给环境带来了较大伤害,对此,我国政府大力推动环境审计实践,重视环境保护工作。国家审计署在2008年把资源环境审计确定为六大审计类型之一,同时生态文明建设在党的"十八大"报告中被提升到了"五位一体"的国家总体发展地位。以中冶美利云产业投资股份有限公司为例,在阐述了我国环境审计的基本概念基础之上,分析了我国环境审计存在的问题及其原因,提出了促进我国环境审计理论和实践发展的建议,以期提高环境审计的效率和水平,推进生态环境保护和自然资源利用的协调发展。     

自然资源产权管理和运行的市场经济模式

在借鉴国外自然资源产权运行模式的基础上，设计了我国自然资源产权管理和运行的市场经济模式．自然资源要实行商品化经营，有偿使用；资产勘查部门应企业化．我国的自然资源市场实际上是一种租赁市场，其由自然资源出让市场与使用权转让市场二级构成．国家对自然资源市场宏观调控的手段和内容；建立健全自然资源法规，明确林业经济的基本政策，建立有权威和效力的管理体制，改革税收体制，建立自然资源储备制度。     

发展林业,改善西部生态环境

通过分析我国西部地区的自然资源与生态环境状况，以及经济环境与林业生态的发展关系，提出了为改善西部地区生态环境而发展林业的策略。     

民法物权法律视角下的我国自然资源立法

我国现行的自然资源立法，经过多年的建设和完善，与历史相比，已经有了很大的进步和发展。自然资源的基本法律制度已初步建立，自然资源的立法体系也已初具规模，且在某些环节和领域还实现了体制与机制的创新。但是，与我国自然资源管理的客观要求以及西方发达国家自然资源立法的实践相比，仍然存在着诸多问题和不足。     

对湖南自然保护区区划浅见

一、概述环境和自然资源是人民赖以生存的基本条件,是发展生产、繁荣经济的物质基础,管理好环境,合理地利用自然资源,是现代化建设的一项基本任务。包括人类在内的生物和环境组成大大小小的各个生态系统,无时无刻地进行着能量交换和物质循环,在一定的时间和相对稳定的条件下,保持着动态平衡,即所谓生态平衡。自然环境和自然资源,都参     

依法治林，保护生态遗产

数据显示，我国环境法律占全部法律的10％左右，环境行政法规占全部行政法规的7％左右。环境法律的门类越来越齐全，结构也越来越完整，涵盖了污染防治、自然资源保护、生态保护、资源循环利用、节能减排、防灾减灾等多个门类。     

关于自然资源价值补偿问题研究

指出了随着经济的高速发展，资源环境问题不断显现，人类与自然界矛盾重重，有关自然资源价值补偿的问题更多地引发关注。从西方经济学价值理论角度论证了自然资源的价值，解释了自然资源没有得到补偿的原因，进而提出了相关的政策建议来正视自然资源价值补偿问题。     

基于农业生态经济系统能值分析的农业绿色GDP核算——以怀化市为实例

运用奥德姆(Odum)创立的生态经济系统能值理论和分析方法,定量分析了怀化市2005年农业经济发展过程中投入的能值总量,计算了所消耗的自然资源的能值-货币价值,并核算了怀化市农业绿色GDP.结果表明:怀化市农业生产总值为702 072万元,如果考虑其对自然资源的损耗,则农业生产总值为634 000万元,即农业绿色GDP占传统GDP的90.31%,也就是说在传统GDP的核算中有9.69%是以无偿"透支"自然资源和对环境的损耗为代价的.表明怀化市传统农业GDP所计算增长的结果是偏高的,是包含了对这些自然资源和对环境的消耗为代价.     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.