赤桉幼林种源试验*

以赤桉４批试验林的４２个种源为研究材料，分析了４～８年生幼林种源间的生长差异，及与原产地地理位置的关系。试验结果表明：（１）种源间树高生长差异极显著，胸径和材积生长除第三批试验林外，均达极显著水平。（２）低纬度种源生长快，高纬度种源生长慢；沿海种源生长好，内地种源生长差。４批试验林种源产地不同，受经纬度影响程度不一样。（３）经指数综合评定，第一批试验林评选出１３６６３、１３６９２，第二批试验林评选出１２５０１、１３９２８、１３９３５，第四批试验林评选出１７２９７、１５０５０共７个速生优质种源，这些种源大部分分布在澳大利亚沿海地区，３个来自昆士兰州北部，２个来自北澳，２个来自西澳州。     

巨桉,柳按种源试验及其生长比较

从巨桉１３个种源，柳桉１４个种源的试验林为研究材料，对生长在海拔１００ｍ，贫瘠山地上的５年生幼林进行分析，并对树种间和种源间的生长差异进行比较。结果表明：（１）在树种水平上，柳桉的生长适应 ，生长速率臁通直度，径高比等方面均比巨桉好，只是在下高不及巨，但树种间差异，除抗寒性特别明显外，其余均洋显著。（２）树种内的不同地理种源之间，树高，胸长和材积生长差异、巨桉和柳桉在幼林３年生时均达显著或极显著异     

江西省赤桉地理种源试验研究初报

１９８６年和１９８８年先后进行了２次澳大利亚赤桉种源的地理试验研究。试验表明，赤桉种源之间树高、胸径生长量存在着显著或极显著的差异，且各种源树高与胸径之间的相关性极强。根据高、径生长量和在极端气候条件下表现出的抗寒能力，２次试验初步筛选出３～４个生长量大、抗寒能力强的种源用于早期推广应用。通过观测，还验证了关于我省桉树最适生长区的划分。     

海南岛东部地区桉树树种/种源试验*

在海南岛东部进行的桉树１１个树种７９个种源试验，５年的结果表明，不同树种种源间生长差异极显著，来自印度尼西亚Ｍｔ．ｍａｎｄｉｒｉ的尾叶桉１２８９５种源是所有参试树种／种源中表现最好的，树高、胸径和每公顷材积分别为１３．８２ｍ、１２．５４ｃｍ和１２８．３４ｍ３。同一树种种源间生长差异也极显著，最佳种源的每公顷材积与最差种源相比，尾叶桉为８．４６：１，细叶桉５．８６：１，赤桉５．３２：１和巨桉３．０４：１。细叶桉、赤桉和巨桉种源树高、胸径和材积生长与原产地纬度显著负相关，尾叶桉种源与原产地海拔高极显著负相关。本文提出了适合海南岛东部地区生长的树种和种源。     

闽西北适栽桉树树种选择研究

自上个世纪90年代以来，闽西北进行了多批桉树树种引种或种源家系试验，结果表明：适宜闽西北地区推广种植的桉树有巨桉、邓恩桉、柳桉和赤桉，其中赤桉、邓恩桉最为耐寒。可以推广到闽西北大部份地区，巨桉、柳桉适宜闽西北较低海拔、绝对最低温度在-5℃以上的地区，但需要选择适宜的种源。树种内种源和家系间的生长性状、抗寒性存在显或极显差异，单株间的生长差异比家系间的生长差异大，而家系间又比种源间大。此外，桉树树种原产地的雨量分布情况对决定引种桉树极为重要。在高温潮湿的福建地区不适宜引进冬雨型桉树树种。     

不同种源巨桉生长、干形和抗桉树枝瘿姬小蜂的综合评价

对9个不同种源的巨桉进行了桉树枝瘿姬小蜂自然侵害后的受害情况、生长性状和干形调查,结果表明:不同种源的受害程度不同,其中,种源南非1/SAG-TER1受害最为严重,种源南非6/SAG-URO受害最轻;不同种源的生长性状表现出显著差异,种源南非6/SAG-URO的树高、胸径、冠幅等指标均最大,且与种源16892和17907有显著差异;不同种源间巨桉树干通直度、圆满度无显著差异,分枝状况有细微的差异,分枝角度有显著差异。相关性分析表明:不同种源巨桉生长性状和干形性状之间呈显著或极显著相关,幼林树高与受桉树枝瘿姬小蜂侵害状况之间呈显著负相关。通过对不同种源的巨桉进行综合分析评价,种源南非6/SAG-URO的抗性最优,可以作为后续抗性选育的优良种源。     

华南地区桉属树种种源生长表现

在华南地区，桉属树种的多点试验结果表明，细叶桉和赤桉的优良种源在各种不同的立地条件下，其近期保存率和立木蓄积量都比当地原主栽树种窿缘桉高１倍以上；在较好的立地条件下，尾叶桉产量最高，该树种最优种源２年生立木蓄积量比最差种源大１３９．２％，细叶桉５年生立木蓄积量最好种源比最差种源大２１．１１倍，赤桉５年生立木蓄积量最好种源比最差种源大６６％。     

桉属树种与种源、家系比较试验

以９个桉属树种，其中８个种泊来自原产地，７个家系和７个杂种后代来自国内次生资源进行混合比较，５年生评价结果表明：树种、种源、家系呈极显著差异；尾叶桉及其两个种源、尾巨桉杂交种细叶桉的１３５４４种源适合本试验区戒严和格短轮伐期经营，可获得适应性和生长指标平均值超过平均水平３５％的选择效应。其中最优为１４５３４号尾叶桉种源，５年生单株材积０．０５０．６１ｍ＾３／株（８９．０３ｍ＾３／ｈｍ＾２）。种子采     

细叶桉种源—家系选择*

对细叶桉３个种源５０个自由授粉家系的生长性状和形质性状进行种源间和家系间差异分析和家系遗传变异及相关分析，结果表明细叶桉主要性状种源间和家系间差异都极显著，种源间的差异大于家系间的差异，来自澳大利亚昆士兰州的Ｌａｕｒａ种源优于其它种源。细叶桉家系生长性状和形质性状呈中度至强度遗传；枝下高、干形和冠幅与生长性状遗传相关极显著。运用指数选择法对５０个家系进行多性状综合选择，初步选出５个优良家系，可望获得２２．２３％的综合遗传增益。     

韦塔桉与大花序桉在粤中地区的生长表现

对韦塔桉6个种源和大花序桉4个种源进行生长与形质性状分析,结果表明:韦塔桉种源各年度生长性状在种源间均存在极显著差异,形质性状差异不显著。大花序桉除早期树高生长外,其他性状的年度生长指标在种源间并无明显差异,干形在种源间存在显著差异,分枝性状差异不显著。韦塔桉种源17835生长表现最好,其平均树高、胸径和单株材积分别达到15.01m、15.03cm和0.1133m3,是平均值的115.82%、116.78%和153.94%。大花序桉种源9901生长表现最好,其平均树高、胸径和单株材积分别达到10.88m、12.95cm和0.0617m3,是平均值的106.35%、106.15%和117.97%。韦塔桉与同地区尾叶桉相比无显著差异,可在本地区作为重要的速生桉属树种育种资源;大花序桉作为珍贵实木用材树种发展前景广阔。     

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.