城市林业在生态城市发展中的作用

指出了森林在维护城市生态环境、改善人类生存空间中发挥了重要作用,为城市带来最大的生态环境效益的同时也带动了城市经济效益和社会效益的增长,极大地推动了城市的生态化建设进程。阐述了生态城市与城市林业的内涵与特点,探讨了城市林业的建设对生态城市经济发展、社会进步和生态化建设中的重要作用,为促进城市林业和生态城市建设与发展提供参考。     

生态化城市建设树种选择及功能性研究

通过对湖南省生态化城市建设树种选择应用中存在的问题进行研究与分析,提出了生态化城市建设树种选择的依据及应具备的功能,即观赏性、抗逆性、生态保健功能、经济效益、文化功能等。     

徐州城市森林建设探讨

随着城市化进程的不断加快,空气污染、热岛效应等城市生态环境问题日渐突出。党的十七大提出了科学发展观,可持续发展是人类社会的共同愿望,在实施城市可持续发展战略中,生态化城市已成为全球城市可持续发展的方向。"生态城市"是城市生态化发展的必然趋势,是社会和谐、经济高效、生态良好的人类居住区形式。城市森林建设是生态化城市发展的重要内容。     

园林设计的生态化策略

指出了生态园林作为城市之中最靓丽的风景之一,它不仅能供居民栖息游玩,陶冶情操,更是提高城市整体观赏性的重要途径之一。目前我国在园林的建设中,着重于生态化园林的建设,生态化园林不仅可以有效地对生态环境进行有效保护,还可以通过其人文环境受到人们的喜爱。对生态化园林进行了全面分析,提出了生态化建设的策略,希望能给相关人员提供一定的帮助。     

北京地区铁路绿化景观建设探讨

<正>北京市提出"人文北京、科技北京、绿色北京"的建设理念,是落实科学发展观、建设和谐社会的集中体现。随着北京城市化进程的不断加快,绿色北京的构建是城市生态化发展的必然趋势。而城区铁路与周围环境的和谐构建即铁路绿化景观建设是生态化城市发展的重要内容之一。     

我国城市林业发展总体规划的研究

城市规模扩大、人口增加、生态环境压力加大,是世界城市发展的一个共同特点。建设生态结构合理、生态服务功能高效的城市生态系统,推动生态化城市建设,已成为世界城市发展的新潮流。       

济南市生态化城市建设调研报告

人类从迁徙转为定居，由农村走向城市，在城市中繁衍生息，写就了5000多年的城市发展史，并奠定了城市作为人类主要聚落形式的基石。城市中的人们在享受丰富多彩的现代化城市文明的同时，却与自然环境疏离得越来越远，精神感到压抑和茫然，备受混凝土城市的困扰。因此，吸取城市建设中的经验和教训，实现城市的生态化，才能把城市建设成为人类理想的家     

西安城市生态景观绿化的七大发展对策

通过实际调查,运用生物生态学原理结合当地的自然、社会经济和绿化状况进行系统分析,提出了西安市城市生态化建设的七大战略措施,为西安、关中以及相似植被区城市的生态化的实施和实际操作提供科学的思路和方法。     

林区城乡生态化建设的策略

当前,生态化建设实践已在我国城乡蓬勃展开。在新一轮跨世纪城乡总体规划中,生态意识已大大提高,全国已有30多座城市明确提出了建设生态城市的发展目标,这些目标的建立是由于政府决策部门和广大群众越来越意识到城乡生态化发展及建设生态文明的重要性和迫切性。     

城市废弃铁路生态化有机更新利用策略

"公园城市"是新时代背景下适应城市发展和转型提出的新理念与新目标,如何通过城市废弃铁路的生态化有机更新推动"公园城市"的建设成为新形势下风景园林所面临的新机遇与挑战。文章以晋中市139铁路公园为例,在"公园城市"理念下提出城市废弃铁路生态化有机更新需要实现"与自然共融、与市民共享、与历史共存"3大层面的目标,并形成以打通城市生态廊道、满足人民美好需求、塑造地域文化特色为核心的城市废弃铁路生态化有机更新策略,实现城市环境品质的提升。     

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.