九寨沟自然保护区森林防火研究

森林作为人类生存和发展不可或缺的自然资源,在推动我国社会经济发展中发挥着至关重要的作用,其不仅可以为工业和农业生产建设提供所需的木材和林副产品,而且在维持陆地生态平衡、美化环境、保持水土、净化空气、涵养水源等方面也都发挥着至关重要的作用。但是和其他自然资源一样,随着人类的不合理开发和利用会极大地影响森林资源可持续性发展。其中以火灾为例,当前森林火灾已经成为破坏森林三大自然灾害之首,而要实现对自然保护区森林资源的保护,首当其冲便是做好森林的防火工作。文章以九寨沟自然保护区为例,通过查阅相关资料和报告,对九寨沟自然保护区森林防火情况进行分析,总结了九寨沟森林防火现状,指出九寨沟自然保护区森林防火中存在的问题,并在此基础上提出了森林防火对策,旨在降低九寨沟自然保护区森林火灾发生率,减少森林火灾引起的人员伤亡和资源损害,从而达到保护九寨沟自然保护区森林资源,保证生态系统平衡的目的。     

牛背梁自然保护区森林防火对策的思考

一、自然保护区森林防火的重要性 众所周知，自然保护区在涵养水源、保持水土、调节气候、净化空气、减少噪音、改善环境和保持生态平衡等方面发挥着重要作用。自然保护区的保护工作也就显得尤为重要。而对自然资源最大的威胁来自于森林火灾，森林火灾不仅难以预防和控制，而且破坏性极大，因此，针对牛背梁保护区的90．12％的森林覆盖率这一实际情况来说，森林防火工作显然成为保护区自然资源保护中最为重要的一项工作。     

林业资源保护及森林防火管理措施初探

我国丰富的林业资源为国民经济发展奠定了坚实的基础,但是我国林业资源还存在着分布不合理、不平衡、森林覆盖率低、人均占有量较小及人为破坏行为严重等情况,因此需要对林业资源加强保护的同时要加强森林防火管理。基于此,从林业资源现状入手,对林业资源保护以及森林防火管理措施进行深入分析,以期能够提升对森林的保护以及防火力度,确保林业资源能够实现可持续发展的目标。     

卧龙自然保护区森林燃烧性分析

卧龙自然保护区位于岷江上游,以保护珍稀濒危动植物资源和生态环境为目的,是一个广谱基因库。自然保护区不允许发生森林火灾,即使是森林火警也不应发生。过去的十多年,卧龙没有发生大的森林火灾,这就使人们产生一种卧龙不会发生森林火灾的错觉,防火意识逐步淡化。本文通过对卧龙自然保护区森林可燃物特性、火环境特点及火源动向的分析,认为卧龙的森林具有易燃的特点,火源和火环境也具备,发生森林火灾的潜在可能性是存在的。这对提高人们的防火意识,加强自然保护区的防火工作,防止发生森林火灾具有重要的意义。一、森林可燃物特点可燃物是森林燃烧的物质基础。可燃物的大小、     

河北雾灵山国家级自然保护区森林防火现状及对策分析

森林防火一直是林区资源保护的重要一环。概述了雾灵山国家级自然保护区森林防火现状,分析了当前防火工作存在的问题,并针对这些问题提出了相应的防控对策和建议,为自然保护区森林火灾防控工作提供参考和借鉴。     

自然保护区的森林防火工作探讨

指出了自然保护区不仅是各种动植物的避难所,也是濒危物种的保存区域。一旦引发火灾,保护区内的动植物资源将会面临毁灭的命运,林区生态系统也会遭到破坏,可以说,做好自然保护区的森防工作,对于生物多样性保护、气候调节以及水源涵养等意义重大。当前,自然保护区火灾形势不容乐观,对动植物的生产生活危害重大。基于此,分析了自然保护区森林防火的现状,就如何做好自然保护区的森林防火工作提出了相应地策略。     

红塔山自然保护区森林防火措施探讨

森林防火是森林资源保护的重点工作,从建立健全森林防火机构、落实森林防火责任、加强森林防火宣传、狠抓火源管理、全面监测森林火情、坚持24小时森林防火值班、加强专业扑火队管理、加强扑火物资管理、建立广泛的森林防火统一战线、强化森林防火监督检查、安全扑救森林火灾、加强森林火灾案件查处等方面,探讨了30年来红塔山自然保护区采取的森林防火措施。     

塞罕坝森林资源保护措施浅析

从资源环境可持续发展和塞罕坝机械林场资源管护中所面临的问题出发,对各种影响因素进行了分析,提出了在林区内部加强保护区建设、开展分类经营、生态旅游、做好森林病虫害防治、森林防火等措施,提高森林资源保护意识,探索维护生态平衡,防止人为破坏,合理开发利用自然资源途径,以实现可持续发展。     

武夷山自然保护区森林防火机制探讨

分析了武夷山自然保护区的地理区位、地形和植被,社区居民和生产经营活动,火灾的发生情况等特点。阐述了武夷山保护区建立的森林防火的联合保护、社区参与式管理等有效机制,以及取得社区经济持续稳步增长、资源保护成效显著等明显成效。     

森林防火助力生态文明建设探讨

生态文明建设是衡量我国国民经济发展的一项重要指标。随着社会方面对于绿色生态环境的大力重视，森林防火被纳入生态文明建设中，其中，加大林业资源保护力度以及全面预防森林火灾隐患，不仅是森林防火工作者的职责所在，同时也是人民群众的基本责任。这就需要做好森林火灾防范工作，防止森林资源受到破坏，从根本上确保人们生命和财产安全，从而助力生态文明建设。     

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.     

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.     

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。     

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.     

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.