粤湘赣乌桕家系在广东从化的早期生长表现

对来自湖南省望城县、广东省连山县、江西省上犹县的3个乌桕种源进行早期生长研究,结果表明,种子千粒重、苗高、幼林树高和胸径在种源间、家系间均达极显著差异水平,种子千粒重与苗高间,苗高与幼林树高、胸径间均表现为较密切的正相关关系;湖南望城种源的种子千粒重、苗高、幼林树高和胸径均最大;经综合评选,筛选出16个优良家系,其中湖南望城、广东连山、江西上犹种源入选家系个数分别为8,4,4个,优良家系树高和胸径的现实遗传增益分别达到23.1%和37.5%     

乐东拟单性木兰地理种源变异与选择研究

对乐东拟单性木兰14个种源种子、苗期以及幼林期生长性状进行了调查分析.结果表明:种子千粒质量、苗高、地径、叶长和叶宽等5个性状在种源间差异极显著;造林保存率种源间差异显著,来自北部的种源,如浙江龙泉种源保存率较高,而来自南部的海南尖峰岭种源保存率较低;幼林期4年生树高、5年生树高和胸径、6年生树高和胸径等5个主要生长性状种源间差异均达到极显著水平,其生长性状广义遗传力为0.855～0.930,说明乐东拟单性木兰幼林期主要生长性状的表型差异主要受遗传因素的控制;乐东拟单性木兰苗高和地径与纬度负相关,表明随种源纬度的升高,乐东拟单性木兰种源苗期生长有减小趋势;乐东拟单性木兰幼林期树高和胸径与经度正相关,与纬度极显著正相关.根据乐东拟单性木兰种源幼林期试验结果,选择出浙江龙泉、福建顺昌和湖南新宁3个优良种源.通过聚类分析,把乐东拟单性木兰种源初步划分为3个区:西部种源区、东部种源区和南部种源区.     

巨桉种源家系多点遗传变异及选择比较

对4．5 a 生巨桉种源／家系3个试验点共13个种源175个家系的生长和形质性状进行遗传分析。结果表明：所有观测性状在地点、区组和家系间均呈极显著差异（P ＜0．01）,胸径在种源间差异极显著（P ＜0．01）,树高、干形、分枝和冠幅在种源间差异不显著;树高和胸径变异系数在地点间差异不大,冠幅表型变异系数为45％～60％,江西南康的分枝变异系数高达34％,广东连山的分枝变异系数仅15％,总体上广东连山试验点各性状变异系数略低于江西南康和云南景谷,冠幅遗传变异系数＞胸径＞树高＞干形＞分枝,景谷点参试性状遗传力＞连山点＞南康点;相关性分析表明：生长性状间、生长性状与冠幅、生长性状与部分形质指标均呈极显著正相关（P ＜0．01）;利用综合指数选择法,筛选1号（昆士兰州 NW Townsille）、2号（昆士兰州 Copperlode）和12号（四川乐山）为优良种源,2号（昆士兰州 Copperlode）、21号（昆士兰州 Barron Gorge National Park）、40号（昆士兰州 Koombooloomba）、51号（昆士兰州 Tinaroo）、125号（昆士兰州 Bambaroo）、127号（昆士兰州 Bambaroo）、137号（昆士兰州 Bambaroo）和144号（昆士兰州Tully Gorge National Park）等家系在两个试验点中同时表现优良,但没有家系同时在3个试验点中表现突出。     

杉木数量性状相关性的研究

研究表明:杉木种子性状间、发芽率与优良度、发芽率与发芽势为极显著相关,而优良度与千粒重为显著相关;千粒重与苗期、幼林的生长性状间的线性相关不显著;同一家系年重复与千粒重之间虽显著线性相关,其它性状相关则不显著;同一家系同年份,苗高、侧枝数有较高的空间重复性,而地径、顶芽数空间的重复性较差;相同家系,树高、胸径和材积生长在不同的地点表现出不同程度的相关系数。树高与胸径生长的相关系数γ值为0.6—0.7;相同家系在不同年份重复中,胸径生长相关显著。     

广西凭祥西南桦种源家系选择试验Ⅰ．幼林生长性状的变异

应用25个地理种源400余个家系在广西凭祥进行西南桦种源家系联合筛选试验,对1～4年生幼林进行了生长性状遗传变异分析,结果表明：（1）不同西南桦种源间和家系间的树高和胸径生长均差异极显著;（2）各种源树高和胸径均与其产地经度极显著相关;（3）不同林龄间种源和家系的树高和胸径生长量的相关分析表明,种源选择的可靠性逐年增加;（4）以4年生时生长性状作早期评价,发现大多数优良种源、家系来自广西,可见西南桦种源选择以就近种源较好。     

西南桦在广东省中部引种初报

西南桦是我国热带、南亚热带地区的优良乡土阔叶树种。文章对广西壮族自治区11个西南桦种源在广东省中部引种的苗期及幼林生长性状进行了分析,结果表明:引种西南桦的地径、苗高以及幼树高生长在种源间、家系间差异极显著,种源内遗传变异大于种源间,家系遗传力高于种源。依据苗期地径选择出表现良好的5个种源,在其中选择出35个优良家系,遗传增益为14.59%;根据苗高在5个优良种源中选择20个优良家系,遗传增益达到21.27%。幼林阶段高生长与苗期略有变化,根据幼树高生长指标在5个优良种源中进一步选出25个优良家系,遗传增益达到10.03%。     

广西凭祥西南桦种源家系选择试验I. 幼林生长性状的变异

应用25个地理种源400余个家系在广西凭祥进行西南桦种源家系联合筛选试验,对1～4年生幼林进行了生长性状遗传变异分析,结果表明:(1)不同西南桦种源间和家系间的树高和胸径生长均差异极显著;(2)各种源树高和胸径均与其产地经度极显著相关;(3)不同林龄间种源和家系的树高和胸径生长量的相关分析表明,种源选择的可靠性逐年增加;(4)以4年生时生长性状作早期评价,发现大多数优良种源、家系来自广西,可见西南桦种源选择以就近种源较好.     

广东3个红花荷种源在海南早期生长表现

对来自广东从化石门、东莞银屏山、台山北峰山的3个红花荷种源早期生长进行研究,结果表明,红花荷种源间的种子千粒重差异不显著,而家系间的种子千粒重差异极显著,种子千粒重与各个生长性状以及各个生长性状间均表现为正相关关系;从化石门种源的种子千粒重、苗高、幼林地径、树高和冠幅均最大。     

黄冕林场大叶栎不同种源/家系子代林的测定结果研究

在位于广西柳州市的黄冕林场进行了大叶栎9个种源、51个家系的子代测试试验。结果表明，在其子代试验林的3年生幼林期，不同种源、家系大叶栎林木的树高、胸径、单株材积等生长性状存在显著差异，据此采用综合评定法从大叶栎种源中初选出14个大叶栎优良家系。所初选的这14个大叶栎优良家系，其3年生子代幼林林木的3个生长性状与最差家系相比，平均树高增长率为23．61％～3．3．33％，平均胸径增长率为37．15％-49．54％，单株材积增长率为124．4-5％～177．84％。     

旱冬瓜优良种源的早期选择

通过对滇西南地区15个种源99个旱冬瓜家系苗木的苗高和地径生长量以及造林后18个月幼林的树高和胸径的测定与分析,结果表明:(1)在旱冬瓜的地理种源间存在着丰富的遗传变异,不同种源苗木在苗期及幼林期的高、径生长上均存在着显著差异,表明在滇西南地区开展旱冬瓜优良种源选择十分必要;(2)旱冬瓜苗期入选的优良种源和幼林期入选的优良种源基本一致,这表明旱冬瓜早期选择可为林木的后期良种选育提供参考;(3)表现较为稳定的优良种源为瑞丽、西盟、潞西、陇川种源。     

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.