土壤水分条件及保水剂用量对侧柏、栓皮栎种子萌发及幼苗生长的影响

造林种子发芽率低一直是太行山干旱山区植被恢复过程中的一个难题。以该地区植被恢复中典型树种侧柏、栓皮栎种子为研究对象,通过控制试验,研究了不同土壤水分条件下不同保水剂包衣用量对侧柏、栓皮栎种子发芽率及生长发育的影响。结果表明,(1)盆栽用土为褐土,土壤含水率为5%时,保水剂包衣对侧柏种子发芽率及生长发育有显著的促进作用,并随用量的增加而增加,以施用保水剂比例1︰3时最佳;土壤含水率为8.5%时,保水剂用量过高则促进作用不明显,出芽率随用量增加而减小,施用保水剂比例1︰1及1︰2时能较好地提高侧柏种子出芽率;土壤湿度过高时,施用保水剂反而会抑制侧柏种子生长发育。(2)盆栽用土为砂页岩,土壤含水率为12%时,保水剂包衣能增加栓皮栎种子出芽率,施用保水剂比例1︰3时最佳;土壤含水率为20%时,保水剂包衣会抑制栓皮栎种子出芽率。     

不同基质对黑格不同家系种子发芽的影响

以5个黑格(Albizia odoratissima)家系种子为试验材料,探讨4种播种基质对黑格不同家系种子发芽的影响。结果表明,发芽率、发芽势、根长、茎长在家系间及各基质处理间均有显著差异。采用黄心土和椰糠播种,根系和茎生长发育好于其他2种基质,但黄心土播种发芽率显著低于其他3种基质,椰糠播种发芽率最高;多重比较分析发现,28号家系发芽率和发芽势显著高于其他家系,76号和16号家系根茎生长较好,57号和84号家系各方面表现相对较差。     

南美油藤播种育苗技术

以南美油藤种子为对象,研究不同品种、气温、播种基质对其发芽情况的影响。结果显示：细沙以及珍珠岩+泥炭两种基质不利于南美油藤种子发芽,轻型基质(黄心土：稻壳：珍珠岩=3：4：3)可使其发芽率超过90%;不同品种的南美油藤种子发芽率差异显著,C和H两个大果种子不发芽,V2和V4发芽率低于15%,V3发芽率可达90%;不同气温影响南美油藤种子发芽率,以气温25~35℃播种为宜。     

羽叶楸种子萌发试验初报

通过研究不同采种时间及不同播种基质对羽叶楸(Stereospermum colais)种子萌发的影响,提高羽叶楸种子发芽率,结果表明:不同采种时间对种子发芽率存在极显著差异,12月中旬(蒴果全部变黑)为最佳采种时间,种子平均发芽率最高,达77.3%;不同播种基质对种子开始出苗时间、完成出苗时间和发芽率均存在显著差异,种子萌发适宜的播种基质为江沙,种子在7 d便开始出苗,完成出苗需28 d,出苗整齐(从开始出苗到完成出苗仅需21 d),平均发芽率为79.3%。     

不同基质和覆盖处理对杜鹃种子萌芽及成苗的影响

为获得高效的杜鹃育苗方法,以杜鹃花‘紫鹤’和‘粉鹤’自交种子为试材,研究了不同基质和覆盖处理对杜鹃花种子萌发、成苗和实生苗形态建成的影响。研究结果表明:以未发酵的玉米秸秆粉末作为播种基质不能使杜鹃花种子发芽和形成实生苗;以园土与干苔藓混合物和园土与棉籽壳混合物作为播种基质仅有少量种子发芽,不利于实生苗的生长;以蛭石和蛭石与干苔藓混合物作为播种基质的杜鹃发芽率和成苗率分别可达到65.33%~81.33%和62.67%~78.67%,但不利于杜鹃花实生苗的形态建成;以草炭和草炭与干苔藓的混合物作为播种基质能显著促进杜鹃花种子的萌发和成苗形成,且杜鹃花实生苗生长发育健壮;覆盖处理则降低了杜鹃花种子的发芽率。     

13种竹种子低温储存条件及种子育苗环境研究

为解决竹子种子长期保存问题,以马来龙竹、云南龙竹、巨龙竹、金平龙竹、麻竹、长节勒竹、云南箭竹、棉花竹、爪哇巨竹、大泰竹、笻竹、方竹和毛竹13种竹子的成熟种子为材料,通过研究不同低温、低温下不同储存时间、不同含水量、不同发芽设施和不同基质对种子发芽率的影响,来判断竹子种子保存的适合条件。结果表明：1）除笻竹和方竹的种子外,大多数竹种的种子在低温储存5个月内,随着温度由10℃逐渐降低到-16℃,种子发芽率会有不同程度的增高;2）在-16℃条件下,随着储存时间的延长,种子发芽率会有所下降;3）种子含水量会在很大程度上影响种子的发芽率,含水量超过在一定临界值,随着含水量的增加,种子发芽率会显著下降;4）选择不同的种子发芽设施也会影响种子发芽率,生产中宜选用具有微喷灌条件的温室进行育苗;5）在无菌红土、黑土和蛭石这3种基质中,蛭石是竹子播种育苗的适宜基质。     

广东省几种野生杜鹃花植物的种子发芽条件研究

应用实验方法检测了广东省10种杜鹃花属植物在不同基质、播种时间、光照条件下的种子发芽能力。结果表明,播种基质影响种子发芽率。所有种在非灭菌根际土上的发芽率均高于灭菌河沙与灭菌根际土,灭菌河沙基质发芽率最低。广东杜鹃(Rhododendron kwangtungense)、羊角杜鹃(Rhododendron cavaleriei)和太平杜鹃(Rhododendron championae)在3种基质上的发芽率都超过50%;杜鹃植物种子的发芽具有需光性,所测试植物的种子在光照条件下的发芽率均远高于遮荫条件;不同播种时间在一定程度上影响杜鹃花属植物种子的发芽率。采种1个月后播种的种子发芽率最高,采种2个月以后才播的种子发芽率明显下降。     

钟花樱桃种子萌发研究

以广东粤东北地区野生钟花樱桃 Cerasus campanulata 种子为试材,研究了温水（25、40、60、 80 ℃）浸泡、不同催芽方式（室外沙藏、室内盆栽沙藏、冷藏、水苔叠放）、赤霉素处理（0.5、1、2、 3 g · L-1 ）和机械破壳处理对钟花樱桃种子萌发的影响。结果表明：（1）不同温度的水浸泡处理对钟花樱 桃种子发芽率的影响差异极显著（P <0.01）,发芽率为：40℃（71.6%）>25℃（41.2%）>60℃（33.4%） >80℃（6.2%）;（2）不同贮藏条件对钟花樱桃种子发芽率的影响也存在极显著差异（P <0.01）,苗圃 沙藏的发芽率最高,发芽率为 91.2%,且种子发芽时间提早了 60 d;其次是室内盆栽沙藏,发芽率为 80.8%,且种子发芽时间提早了 120 d;（3）不同浓度赤霉素处理对钟花樱桃种子发芽率的影响差异极显 著（P <0.01）,在 0.5 g · L-1 浓度赤霉素处理下其发芽率最佳,发芽率达 95.6%,且种子发芽时间提早了 95 d。因此,钟花樱桃种子最佳的催芽方式为 0.5 g · L-1 浓度赤霉素浸泡 24 h 后进行沙藏。     

圆齿野鸦椿播种育苗技术

研究沙藏催芽处理和不同浓度赤霉素对圆齿野鸦椿种子发芽率的影响,以及不同基质播种育苗的差异和不同播种量对苗木生长的影响。结果表明,圆齿野鸦椿种子沙藏催芽至第3年的2-3月份春播,用不同浓度赤霉素处理均能显著促进其发芽,发芽率最高达75%,出苗快而整齐;以沙壤土加竹炭粉为播种基质,播种量为6.0g.m-2的Ⅰ、Ⅱ级苗产量最高,生长均匀整齐,是最佳播种育苗组合。     

奥氏黄檀种子萌发试验初报

奥氏黄檀属红木类珍贵用材树种,在常规条件下,奥氏黄檀种子发芽率相对较低,通过研究不同贮藏方式、不同种子处理及不同播种基质对奥氏黄檀种子萌发的影响,提高奥氏黄檀种子发芽率,结果表明,播种前,采用40℃温水浸泡自然冷却,再用冷水浸泡24h,种子发芽率为70.3%,高于其它处理;为保持种子有较高的活性,应将种子贮藏在低温(4-5℃)的环境中,发芽率较高,为69.3%;奥氏黄檀种子萌发适宜的基质为江沙+林地表土(体积比1︰1),种子在18d便开始出苗,完成出苗需33d,发芽率为72.7%,均高于其它4种基质。     

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.