苏北地区常绿树种造林应用情况调查分析

对徐州、宿迁和连云港3市近年来造林绿化工程中常绿树种应用情况进行的调查分析结果表明,常绿树种应用频度在94.1%,其中乔木树种的应用频度达88.5%,一般常绿乔木的应用数量已占全部乔木数量的1/3至2/3。3市造林中使用的常绿树种有35种,其中乔木树种只有14种,灌木21种,乔木树种中女贞应用频度最高(75%),其次为雪松、香樟和广玉兰;灌木树种应用频度最高的为红叶石楠,其次为大叶黄杨和海桐;香樟在苏北地区冻害严重,生长势很差。     

重庆主城区边坡绿地植物群落的结构分析

以重庆主城区边坡绿地为研究对象,调查分析了边坡绿地物种组成、配置模式、乔木层亚层数及外貌特征。结果表明:在调查范围内,边坡绿地共有植物83种,群落中最多有16种植物,具有4种植物的群落比例最大(27.27%);有9种配置模式,"灌+草"型的群落最多(25.00%);有75.00%的群落无乔木层结构或仅有单层乔木层结构;乔木层常绿与落叶树种的种类和数量比例分别为1∶2.57、1∶2.09。     

武威市绿化树种调查与优化

为了对武威市绿化树种现状进行分析评价，选择武威市城区典型绿化区域对绿化树种构成、应用频度、生活型、开花特性、观赏特性、生态适应性及应用形式进行调查，结果表明，武威市建成区共有城市绿化树种113种（含变种、变型、品种），其中常绿树种18种，落叶树种95种；乔木48种，小乔木25种，灌木42种，藤本3种；观花树种50种，观叶类树种28种，观果类树种15种，观枝类树种6种；完全适应当地气候条件树种78种，基本适应25种，适应较差10种；栽植方式有孤植、列植、对植、丛植、丛植、群植等6个，配置模式有乔+灌+草、乔+草、灌+草、乔+灌、乔+乔等5个。根据应用频度、栽植数量、生态适应性、用途分为5类，其中基调树种5种，骨干树种15种，常规树种71种，试用树种10种，特用树种12种。     

诸暨市城区主要街道树种多样性与配置模式初探

采用抽样法对诸暨市城区50条主要街道绿化树种的种类及其生长状况进行了实地调查,运用物种出现频度、物种多样性指数等指标对街道绿化树种多样性及其配置模式进行了分析.结果表明:渚暨市主要街道的绿化树种有66种,隶属39科,其中乔木12科19种、灌木20科32种、地被植物7科16种;乔木类使用频度最高为香樟34.57%,灌木类使用频度最高为红花拯木9.77%;绿化树种多样性指数2.0～2.5的街道最多,占30%;树种的配置模式有乔木单层结构、乔灌两层结构和乔灌草三层结构,其中三维空间的立体结构类型的街道有11条,占所调查街道的22%.但诸暨市城区主要街道绿化树种的物种多样性偏低,城市绿化景观特色还不够鲜明.     

河北省城市园林绿化树种应用现状与分析

以河北省2007-2008年主要城市园林绿化植物应用普查为契机,对11个设市城市园林绿化树种应用现状进行统计分析和研究,包括树种种类组成、主要树种比例、树种生长适应性等现状,指出目前河北省城市园林树种应用存在以下问题：树种种类不够丰富;乔、灌比例失调;树种应用频度较低;乡土树种应用比例不高;树木养护管理有待加强等。针对存在问题,提出见解,以期为未来的发展方向提供指导。     

呼和浩特青城公园植物种类及群落景观评价研究

文章对呼和浩特青城公园绿地中植物种类进行了调查,从乔、灌、草比例、物种丰富度、物种多样性、自然度、群落层片等指标对青城公园的草坪、植物种类及群落进行了分析。结果表明:青城公园内树木种类共计43种,其中乔木29种,灌木13种,藤本1种;乔、灌、草比例为1∶1.1∶30.8,草坪质量等级为良;公园内本土植物占全部植物种类的68%,青城公园绿化植物种类的选择非常注重本土植物的开发,而草坪是引进类,草坪草种本土化还是一项非常艰巨的研究任务,有待于开发。     

青海格尔木天然胡杨林群落结构特征浅析

通过对格尔木天然胡杨林群落的植物组成、生长量等特征调查,经统计分析得出:1天然胡杨林的植物有83种,24科55属,其中天然乔木只有胡杨1种,灌木树种有39种,草本植物有43种;2胡杨平均树高为4.35±0.3513m,树高在2.0~≤4.0m的胡杨比例占50.0%为最多;平均胸径为13.67±1.6459cm,胸径在5.0~≤10.0cm的树木占33.3%为最多;平均密度为212.5(N/hm2),样地GH2(E94°22′171"N36°25′878")的密度最大为15875N/hm2,综合林分密度、平均树高、平均胸径、树干基盖度、更新幼苗数和倒枯比例6个指标,综合指数最高的样地是GH2为26.13;3胡杨林中频度≥5%的灌木树种有13种,平均树高为0.9m,平均冠幅为0.7m,平均频度为25.6%,其中柽柳的种类和数量最多;4频度≥20%的草本种类有21种,出现频度最大的是苦豆子、冰草、假苇拂子茅和芨芨草。     

宁夏同心县园林绿化树种选择浅析

在对同心县绿化树种调查的基础上,根据当地气候条件、土壤等自然条件以及县城现状和发展需要,对能满足当地园林绿化要求的植物种类与品种做出了选择和配置原则。调查表明:同心县现有绿化树种83种,分属28科。其中,落叶乔木37种,常绿乔木8种,常绿灌木3种,落叶灌木31种,藤本4种;乔、灌木比例为3∶2,落叶与常绿树种的比例为6∶1;绿化树种的花期主要分布在3-7月。     

太原市城市道路绿化模式研究

对太原市47条道路进行实地调研,统计与分析其道路绿化断面形式以及不同绿化带的典型配置模式。结果发现,太原市道路断面结构以一板二带式与二板三带式为主;绿化树种较为丰富;绿化搭配层次饱满,常用绿化配置结构为乔木+灌木+绿篱。分析道路绿化植物应用现状,探讨道路板式及典型绿化配置模式。提出降低植物种植密度,选择乡土树种,合理配置树种比例,增加布局曲线性与多样性,充分运用树木观赏要素等建议。     

泰州市海陵区主干道行道树应用现状及优化对策

以泰州市海陵区29条主干道路行道树为研究对象,调查了树木种类、垂直结构、径级结构、生长现状、观赏特性,结果如下:海陵区行道树分别隶属于16科22属,共计有27种,53 532棵。其中落叶树种与常绿树种比例为1∶1.1;乡土树种与外来树种比例为1∶1.8;速生树种、中生树种与慢生树种比例为3.1∶2.4∶1;行道树胸径处于Ⅰ级范围的最多,占总数的41.9%,其次是Ⅱ级范围,占36.8%,Ⅲ级和Ⅳ级数量大致持平,均在10%左右。在行道树选择上存在行道树截干苗使用比例过高、种类单一、乡土树种应用少、部分树木生长不良等问题,并提出相应的优化对策。     

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.