天然林保护工程中的森林经营技术讨论

基于天然林保护的内涵,探讨天然林保护的重要意义,阐述天然林与林业发展的关系,研究提出天然林保护工程中森林经营技术的应用.为天然林保护工程的更好实施提供一定的参考.     

论河南省天然林保护工程区的天然林保护与森林可持续经营

通过对河南省天然林保护工程区林业现状和天然林保护工程措施的分析 ,探讨了工程区森林资源可持续经营存在的问题及保护工程对森林可持续经营的促进意义。     

文山州天保工程力促生态建设

文山州紧紧抓住实施天然林保护工程这一千载难逢的历史机遇,以天然林保护工程为依托,加大现有资源的保护管理,积极开展森林防火、林政管理、森林病虫害防治、农村能源建设;抓好天保工程各项目的实施,将全州森林资源保护和林业产业发展推向分类经营的轨道;林业产业得到有效优化和有序调整,全州实行以生态建设     

天然林资源保护工程与林业分类经营

天然林资源保护工程(以下简称“天保”工程)是林业部门调整森林经营方向,在国土保安的前提下,实现林业可持续发展的一次重大改革。科学地实施这一工程,可以扭转我们长期坚持的大木头思想,尊重科学,实现由传统林业向现代林业的转变。     

面向21世纪的森林生态系统经营与天然林保护工程

森林生态系统经营的实质是维持森林生态系统的长期健康稳定和持久的林地生产力，其核心是建立起一个自适应机制，它是天然林保护工程的理论基础。本文论述了森林生态系统经营的概念和实质，在该理论指导下天然林保护工程是一项关系到自然、经济、社会的复合生态系统。     

发展短周期造纸工业原料林势在必行

建设比较完备的林业生态体系和比较发达的林业产业体系是我国林业近期的奋斗目标。为此,必须尽快实施森林分类经营,合理布局、协调功能、完善机制,充分发挥森林各种功能,不断优化生态环境,增加林产品有效供给,确立高效可持续发展的现代林业的主导地位。 我国森林总量不足,分布不均,一些地区森林资源遭到严重破坏,生态环境日益恶化、自然灾害频繁发生。为保护好天然林资源,加强生态环境建设,从1998年起,天然林保护工程全面启动,国家林业局明确提出要大幅度调减现有天然林采伐量。据有关资料表明,2000年生产用材供应量仅为1.19亿立方米,木材供应缺口达     

郴州市天然林管护工程问题及对策

随着我国林业事业的不断发展,天然林保护工程开展愈发受到人们的关注与重视。作为天然林保护的主要手段之一,森林管护开展关乎到天然林保护工程实施质量与效果,影响着我国生态环境的改善。基于此,以郴州市天然林保护工程实施现状为切入点,分析了森林管护工作尚存问题,提出了科学解决的对策来强化森林管理工作水平与效果,为天然林保护工程的高效全面落实打下良好基础。     

天西实施“天保工程”必须抓好的关键环节

天然林保护工程是党中央、国务院从保护资源环境,建设生态林业,实现经济和社会可持续发展战略的高度出发,提出的一项功在当代、利在干秋的重大战略决策。天西林区要实施好这项工程,必须在全局认真树立生态效益第一的思想,切实抓好森林分类经营、强化资源和林地监管,加快后备森林资源培育,作好产业结构调整与职工分流几个关键环节的工作。1全局工作必须以天然林保护工程为重点,彻底转变林业经营指导思想实施天然林保护工程,是党和国家在世纪之交提出的一项英明兴国决策,不但能有效地缓解找国天然林消耗过度、生态环境恶化的现状,…     

安宁市生态公益林效益补偿机制研究

安宁市是云南省实施国家天然林保护工程县之一，根据全国重点地区天然林保护工程森林分类区划的要求，共区划生态公益林面积88288．9hm^2，占林业用地面积的92．2％，生态公益林的补偿机制尚未建立。文章结合安宁市森林分类经营生态公益林区划结果和安宁市的情况，对安宁市建立生态公益林效益补偿机制进行初步研究。     

后续产业成为林区新的经济增长点

由于国家森林经营政策的重大调整,实施天然林保护工程后,特克斯林场认真肩负起了天然林保护工程实施重任,并依托林区自然资源优势,以森林旅游业、畜牧养殖业、种植业为突破口,引进现代企业制度管理,积极开展林业后续产业,对富余职工合理分流,提高林业经济效益,实现了产业结构调整的平稳过度。     

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.     

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。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.