辽东半岛山区近自然经营红松人工林物种组成与群落特征

探究短期和中长期近自然经营下红松人工林群落的物种组成、区系成分与生物多样性等群落特征，为辽东半岛山区红松人工林恢复及生物多样性保护提供参考。以近自然经营12 a和45 a红松人工林为研究对象，利用群落样地调查法记录样地物种信息，分析群落特征与物种多样性。研究表明：1)12 a群落中，共有高等植物29种，隶属于19科23属；45 a群落中，共有高等植物54科96属142种；2)随着红松生长发育，群落物种分布类型增加、物种数增加、分布范围扩大，物种分布类型中，物种数量分布情况为北温带分布>世界分布>东亚和北美洲间断分布，温带成分最多，世界成分次之，热带成分最少；3)红松群落从12 a经营到45 a仍然保持纯林状态，但群落物种多样性显著增强，正向演替趋势明显。红松人工林近自然经营周期很长，正向演替明显，短期经营群落生物多样性较低，直到经营中期生物多样性才显著增强，生态位和密度制约理论能很好解释红松人工林生态演替，对辽东半岛红松人工林恢复具有很好的指导作用。     

南方红豆杉天然群落的物种多样性和群落分布格局的研究

采用罗盘你定位测定的方法，对井冈山较大的南方红豆杉天然群落的物种多样性和２分布格局进行研究，结果表明：群落的物种多样性指数较高，在４．８－５．２之间；属的地理成份多样化，每个群落含有１０个以上属的分布区类型，每个属的物种含量为１．３－１．４种。另外，群落的物种多样性在较小的区域范围有适度干扰种生境选择规律。群落内部南方红豆杉的分布格局２表现为空间和时间上的规律。     

岳麓山风景名胜区枫香群落研究

枫香为著名的观赏树种。本文从群落结构、物种多样性和种群动态三个方面，对岳麓山风景名胜区枫香群落进行了定量研究。结果表明：枫香重要值高达198．83(占总重要值的66．28％)，为主要建群成分，但群落结构简单，物种多样性指数低，群落处于演替的衰退阶段。     

肉桂经济产量分析

从７５个样地产量分析，肉桂有３种经营类型：一种以收获枝叶、提炼桂油要经营目的，第一次收获期为５年生，其后的萌芽林２－３年收获一次，达到同产的收获密度为１．０５－１．２０万株／ｋｍ＾２，一类立地类型组枝叶产量９４７４ｋｇ／ｈｍ＾２以上；一种以收获桂皮药材主要经营目的，种植１０年后方可达到高产，收获密度０．６０－０．７５万株／ｈｍ＾２，一类立地类型组桂皮产量１９６１ｋｇ／ｈｍ＾２以上；另一种是枝叶、桂     

卧龙自然保护区山地暗针叶林不同生态恢复过程中群落α多样性的比较研究

本文以人工林和天然次生林两类群落类型为研究对象，按生态恢复所经历的时间，把群落年龄归为A1、A2、A3和A4四个阶段。通过对两种生态恢复过程中群落α多样性动态变化规律的研究发现；(1)自然演替状态下，乔木层多样性变化不大，A1～A3阶段的灌木层多样性大于A4阶段。A1和A4阶段，草本层的多样性明显比A2～A3阶段大；A1～A3阶段人工林灌木层和草本层多样性有逐渐增大的趋势，到A3阶段人工林群落还没有达到稳定状态；(2)A1阶段天然林灌木层物种多样性大于人工林，随着演替的进行两者逐渐趋于一致；A1阶段天然次生林草本层多样性远大于人工林，从A2阶段开始人工林草本层多样性反而超过天然次生林。     

河西走廊西段荒漠戈壁灌木群落物种多样性的海拔格局

【目的】分析河西走廊西段灌木群落结构特征在海拔梯度上的分布规律,探讨荒漠戈壁灌木群落物种多样性的空间分布格局。【方法】以甘肃荒漠戈壁灌木群落为对象,在800～3 200 m的海拔范围内设置12个海拔梯度,探讨物种多样性沿海拔的变化特征。【结果】荒漠戈壁灌木群落类型沿海拔从低到高依次有沙拐枣+梭梭群落、泡泡刺群落、沙拐枣+泡泡刺群落、泡泡刺+红砂+沙拐枣+膜果麻黄群落、合头草+红砂群落、泡泡刺+红砂群落、合头草+盐爪爪+红砂群落、灌木亚菊+细枝盐爪爪群落、合头草群落、盐爪爪群落、盐爪爪+红砂群落、红砂群落,其中,红砂、合头草和泡泡刺等为分布范围较大的优势种;群落的α多样性指数沿海拔梯度从低到高呈先增加后降低的单峰型分布格局,最大值出现在海拔2 000～2 200 m内,其中,丰富度Gleason、Margalef指数和多样性Shannon-Wiener、Simpson指数随海拔上升表现出显著的单峰型格局(P0.05),海拔显著影响荒漠戈壁灌木群落的物种多样性(P0.05);虽然年均降水量和年均气温与海拔极显著相关(P0.01),但物种多样性与年均降水量和年均气温的相关性均未达到显著水平(P0.05);群落物种多样性指数偏低,群落结构简单,物种组成稀少;大多数相邻海拔梯度间灌木群落的Jaccard相似水平较低。【结论】河西走廊西段荒漠戈壁以灌木为优势种的群落呈区域性的斑块状分布格局。不同海拔梯度内灌木群落的建群种都发生了变化。物种多样性在海拔梯度上呈先升后降的单峰分布格局。     

广东省红树林植物群落分布与演替分析

文章介绍了广东省红树林的资源现状，包括红树林的种类、群落类型、数量、分布、群落演替类型及生长环境等；分析了广东省红树林植物群落的分布规律及广东红树林植物群落的4个演替阶段；指出红树林演替系列是与生态序列相一致的演替特征。     

福建万木林省级自然保护区苦槠群落特征研究

对福建万木林省级自然保护区苦槠天然林的群落结构、物种组成、多样性及演替趋势等进行调查分析,结果表明:该群落的物种多样性较丰富,共有维管束植物36科58属79种,群落中木本植物占绝对优势;群落层次分明,有乔木、灌木和草本3个层次;乔木层中苦槠的重要值最大,但在灌木层中未见苦槠分布,表明苦槠林正处于缓慢演替之中。     

安宁河北部流域云南松群落林分径阶大小多样性研究

采用1 km×2 km机械布点的方法，在四川省德昌县安宁河流域北部区域,共调查云南松树种组成≥6成的样地74块，探究云南松群落的林分直径大小多样性。结果表明：74个调查样地中，共调查胸径≥5 cm的乔木树种2 758株，平均密度为932株·hm^-2；径阶以6～20 cm为主，占总株数的84.63%；云南松径阶香农-维纳指数和辛普森指数较总体的波动幅度大；典范对应分析表明，径阶的分布及其多样性主要受到密度、海拔和坡度的影响。综上所述，云南松群落林分通过密度、海拔和坡度的变化，影响了其径阶大小的多样性。     

燕山东段森林群落及灌木群落枯落物的研究

燕山东段森林群落枯落物现存量平均为４．３５－２８．６７ｔ／ｈｍ＾２，以山杨混交林、松栎混交林、椴树混交林最高，栎林和油松林次之，侧柏林最低。灌木群落枯落物现存量平均为４．１５－１８．９４ｔ／ｈｍ＾２，低于森林群落。森林枯落物现存量受树种组成、年龄、立地条件及人为干扰的影响。其中，人为干扰影响最大，几乎使枯落物损失殆尽。森林枯落物营养元素总贮量０．１７６－１．５３４ｔ／ｈｍ＾２，最大贮水量３．９－５     

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。     

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.     

Key Habitats in the Norwegian Production Forest: A Case Study

This study investigated the forest history, structural characteristics, the presence of fungal species suggested to indicate ecological continuity in old-growth forest, and the species composition of saproxylic beetles in 30 old forest ''woodland key habitats'' (WKHs), and compared them with production forest in the same age-class in south-eastern Norway. No statistically significant differences in forest characteristics, community of saproxylic beetles or number of red-listed beetles were found between the WKHs and the production forest, probably owing to a combination of profound long-term logging and a lack of will to delineate sufficiently large WKHs in the one area with significantly less forestry impact. The study indicates the advantage of including forest history information in WKH selection where such data exist, and the importance of restoring habitats in heavily exploited forest landscapes.