重视发展社会林业 推动山区综合开发

我国山区发展的历史表明，山区经济的发展、良好生态环境的维持都与森林的枯荣盛衰密切相关，所以，山区综合开发建设要以林为本．山区综合开发要在增加农民收入、发展地方经济与保护森林资源、改善生态环境的结合点上找出路，而出路就是发展社会林业．社会林业是山区综合开发建设最稳妥、最可靠、最有效而快速的途径．     

内蒙古阴山山地山杨更新

内蒙古草原带的山地，山杨分布面积欠于白桦，或于白桦以不同的比例组成混交林。它是山地森林的主要类型之一，是护坡林及痧资源涵养林的重要树种，为增强水源涵养，防止水土流失，保护生态环境，加速三弱防护林体系的建设，实现要业可持续的发展，应加强内蒙古山区山杨更新措施的研究。经多年试验，采取开沟进行山杨人工促进天然更新，是一个可以大力推广的适用技术。     

论大青山林业的作用与发展对策

呼和浩特地区的大青山、具有立地生产力较低,人工林和天然林年龄小等特点。大青山林业的发展,对涵养水源,调节气候,改善生态环境,维护生物多样性,供应城乡居民所需的用材、烧柴及果品、提供游乐场所等方面起着重要作用。其发展方针是：把山区的水源涵养、水土保持和生态环境建设列在首位;以林为主、协调农、果、林、牧的关系,森林的培养,要采取封山育林和人工造林并重的政策;把经济林的发展和其他林种结合起来,重视自然保     

山区森林的发展方针

我国是个多山的国家。山地森林在国土绿化和生态平衡方面起着举足轻重的作用。为了促进山区建设沿着正确的发展道路前进,本文根据我们多年的工作经验和调查研究结果,结合河北省的情况,就山区森林的发展方针问题,做一个初步探讨。 一.山区森林的特点 (一)立地条件较差,生产力较低 河北的山地可分为三大部分:太行山地位于西部,冀北山地和燕山山地位于东部。山地北连高原,向南则呈弧形由北和西面包围着平     

禄幼县转龙镇森林资源特点及林业发展措施

转龙镇森林资源具有宜林荒山荒地面积少，覆盖率高；森林质量差；中幼林比重大，可采资源少；森林类型单一，单位面积蓄积小等特点。其山区面积占总面积的９０％以上，山区脱贫致富的最大优势在于山，为此提出林业发展措施；①采取有效的技术措施把现有的近万亩板栗其地管理好，并适度发展鲜果类经济林；②加强幼龄林的抚育和林分的封山育林工作；③进行山区林业综合开发，大力开发以华山松为主，旱冬瓜、云南松为辅的用材林造林和低产林改造工作；④利用区位优势，发展森林旅游业。     

长江洪涝灾害的原因与森林水文生态效应机制

探讨了1998年长江、松花江和嫩江流域发生特大洪涝灾害的原因，有自然因素的影响，但人为因素诸如滥伐森林、围湖造田和在河滩地搞违章建设等促成此次洪水灾害的严重性。山区林区生态环境恶化，山下平川地区遭殃，历来如此。应强化保护森林，加快长江中上游防护林体系生态工程建设，充分发挥山地森林的水文生态效应机制，对江河湖泊及其流域进行综合治理，协调行动。     

塞罕坝陆生珍贵、濒危野生动物及保护

塞罕坝陆生珍贵、濒危野生动物及保护张向忠，胡永富，侯建华（塞罕坝机械林场，围场０６８４６６）（河北农大林学院，保定０７１０００）塞罕坝位于河北省最北部，是辽宁、内蒙、河北三省交界地带，高原、山地兼备，森林、草原并存，区域内生态环境复杂多样，是一个特殊...     

建设生态林业发展旅游经济

南岳之胜在山，山之胜在林。森林既是构筑南岳生态环境的主体，又是南岳旅游经济发展的基础。作为以旅游立区的南岳区，其主要任务：一是建设好生态林业，改善旅游环境，培育旅游资源；二是发展旅游经济，把生态林业变为经济资本，让森林在经济发展中发挥最大的效益。随着我国加入WTO，党中央、国务院非常重视生态环境的建设，把改善生态环境提高到关系到中华民族生存和发展的长远大计来抓。省委、省政府对我区生态环境建设非常重视。省委书记杨正午先后作了重要指示，省林业厅葛汉栋厅长多次莅临南岳研究、考察林业工作。由于领导重视，…     

从镇雄县看滇东北核桃产业的发展

云南是典型的山区省份,全省94%的国土面积是山区,近3400万人居住在山区半山区,占全省总人口的70%。念好"山"字经,做好"林"文章,是"三农"工作的重要内容,也是社会主义新农村建设的重要支撑。省委省政府高度重视山区特色林产业的发展,作出了加快林业发展建设森林云南的决定,出台了《加快木本油料产业发展的意见》,把以核桃为主的木本油料产业发展,作为发展山区经济,改善农村生态环境,加快社会主义新农村建设的重大举措。     

融水山区综合开发治理与林业可持续发展探讨

融水苗族自治县地处桂北山区 ,是国定贫困县 ,林业在全县国民经济中占有很重要的地位 ,林业可持续发展是全县山区可持续发展的重要基础。融水县山区林业可持续发展的内涵和特点第一 ,融水县位于珠江流域的上游 ,是国家确定的首批５０个“珠江防护林工程”建设重点县之一 ,广西三大暴雨中心之一 ,要求山地森林具有更高的水分涵养和土壤保持功能 ,水土保持要求渗透到一切山地森林的所有经营活动中去。第二 ,具有由山地生态环境的立体性和多样性衍生的森林生态系统本身的多样性以及森林生态系统中的动物、植物、微生物的多样性以及这些物种遗传…     

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.