祥云县象鼻水源林保护区可持续发展思路

祥云县象鼻水源林保护区自然泉水由五十年代初的0.3m^3/s减少到现在的0.2m^3/s，洪峰流量从五十年代的9.3m^3/s，增加到九十年代的69.3m^3/s，生态环境逐渐恶化。为了恢复植被，改善生态环境，必须以生物治理和工程治理有机的结合，采取植树造林、封山育林、退耕还林、以煤代柴、节能改灶、建沼气池等生物治理和谷坊、拦沙坝、坡改梯等工程治理措施。     

封山的回报

位于广西大化县西部的贡川乡古方屯，是个四面石山环抱、风景迷人的小屯。从1987年以来，该屯把后背山、巴洪山和弃盘山共400来亩的山林死封，现在森林覆盖中达75％。山上樟树、榕树、金钢木和竹子纵横交错。更大的奇观是，村前一百多米处低洼地长有18株无名的大树，高耸入云。据老人们介绍，该树已有150多年的树龄。由于古方人爱山爱树爱绿，10余年的封山育林也得到了回报：泉水重冒80年代初，山脚几处泉水曾断流，全屯人每天只有到半山腰去排队取水。现在良好的植被依枯泉重又流水潺潺。猴子归山据村民陆正平汇报，1996年春以来，这里年年…     

泉水重新流出的启示

前不久，笔者前去荣获全国实践“三个代表”先进集体的通渭县华家岭乡大牛村参观，在山湾里碰到一位60多岁的老农，牵着一头大黄牛在山泉旁饮水。老农高兴地说，这泉水在上个世纪七八十年代干涸了，这几年又流出了清粼粼的泉水。为什么又流出来了?他说这是山上栽了树的原因。这样重新流出来的泉水有多少眼?老农说，全村一共有     

长江流域森林植被的水土保持作用

根据长江流域特别是三峡库区的调查和研究资料，论述了长江流域历史上自然植被的破坏情况，指出自然植被的破坏历史，就是长江流域水土流失的发展史。对三峡库区１９个县市５０年代与８０年代森林覆盖率比较和森林现状分析，表明三峡库区森林植被破坏十分严重，目前森林覆盖率平均只有１９．５％；同时库区自然植被出现逆向演替，即植被退化，并指出了植被退化的一般规律。根据对三峡库区不同土地利用状况下土壤侵蚀和产沙情况的调查资料分析，表明这一区域侵蚀产沙的主要面上来源是沿江的农田，库区长江河谷两岸大量存在的崩塌和滑坡也是侵蚀产沙重要的点来源。通过对三峡库区各类土地利用方式侵蚀程度、面积和比例的统计分析，反映出三峡库区土壤侵蚀状况是随着森林植被的逆向演替而相应发展和加剧的，森林植被保护和建设是长江流域水土保持的根本性措施。     

杨善洲：坚守信念 绿染大亮山

2010年春天．已持续半年的干旱让云南很多地方群众的饮水变得异常困难．施甸县大亮山附近群众家里的水管却依然有清甜的泉水流出。他们的水源地正是大亮山林场。近些年．随着大亮山植被状况明显改善．山林的水源涵养功效得以很好发挥。附近村委会架起水管，将泉水从林场引到村里．通到各家各户．村民再也不用为吃水犯愁。受旷日持久的干旱影响．水管里的流水较之以往细小了很多，但足以让附近的村民心满意足，也让他们对杨善洲的功劳更加念念不忘：     

闽东北鹫峰山顶部植被演变规律的初步探讨

闽东北鹫峰山项部植被经过半世纪的演变进程，森林经多次火烧、放牧，到20世纪70～80年代演变为草地，之后经过20多年的人工造林、封山育林，到21世纪初再次演变为森林。文章分析了鹫峰山顶部草地的形成与植被恢复，旨在为探讨植被恢复措施提供参考。     

贵州喀斯特山地近自然人工造林技术

生态问题是当今研究的热点，生态环境的好坏将在很大的程度上决定着人们的生存质量。20世纪80年代以来，随着人类活动的加强，喀斯特山区生态退化严重，石漠化面积不断加大，严重地阻碍了国民经济建的发展。植被的恢复，特别是森林植被的恢复是改善喀斯特区生态环境的根本。从上世纪年代开始，由朱守谦、杨世逸、喻理飞、祝小科等组成的研究团队，     

三峡库区坡地植被—土壤环境变化及土地利用的研究

三峡库区现有坡地植被是由亚热带常绿阔叶林演替而来的天然次生林和荒地草坡及人工林植被。森林覆盖率从２０世纪４０年代的４５．５％降至１９８５年的２１．７％，而且面积分布不均匀呈“岛状”和“斑块状”。坡地植被的退化导致了土壤瘠薄。     

中国森林植被碳储量总量78．11亿吨

我国森林植被碳储量总量78．11亿吨，其中，乔木林占85．29％；疏林地、散生木和四旁树占7．59％；灌木林占4．58％；竹林占2．54％。中国森林植被碳储量主要集中在东北和西南地区，分别占全国的20％和40％。乔木林总碳储量中天然林占83．05％；人工林占16．95％。以栎类、杉木、     

戈壁地的珍稀野生动物——记马鬃山地区双峰野骆驼、北山羊和蒙古野驴

戈壁，是蒙古语“高博”一词的音译。戈壁是自然地理名称，汉代称沙碛，后来的历史记载中多与沙漠联系在一起使用，如“戈壁沙漠”、“荒漠戈壁”。戈壁地区的显著特点为：地表裸露，被砾石或低山地带的小碎石覆盖；植被稀疏，大面积为无水区，个别地段虽有泉水，但多为含氟量高的苦水     

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.