格氏栲种子不同催芽方式发芽效果分析

采用粗河沙、粗骨性黄壤、育苗基质、杉木皮屑、薏米屑等5种不同基质及塑料箱、泡沫箱两种不同容器和苗床进行格氏栲种子催芽效果比较试验。结果表明:不同催芽基质格氏栲种子的发芽率、发芽势、发芽指数以粗河沙的指标值最高,3项指标值分别达96.2%、81.5%、21.6%,发芽速度最快,平均9.0 d种子全部发芽结束;粗骨性黄壤的效果稍次,育苗基质的效果中等,杉木皮屑、薏米屑2种基质的效果最差。不同容器与苗床催芽格氏栲种子的发芽率、发芽势、发芽指数以苗床催芽的指标值最高,3项指标值分别达95.2%、85.8%、23.0%,发芽速度最快,平均8.3 d种子全部发芽结束;泡沫箱催芽的效果较差,塑料箱催芽的效果最差。     

温度和光照对厚荚相思种子萌发特性的影响

通过对厚荚相思种子在不同温度及光照下发芽率、发芽势、发芽指数的测定,研究了温度与光照对厚荚相思种子萌发特性的影响.结果表明温度对厚荚相思种子的发芽率和发芽指数的影响极显著,而对发芽势的影响不显著;光照周期对厚荚相思种子的发芽率、发芽势及发芽指数的影响均不显著;在25 ℃或者25/15 ℃的温度下催芽,厚荚相思种子的发芽率、发芽势及发芽指数均最高;光照对种子萌发无影响.     

不同温度层积处理对蓝莓种子萌发的影响

为提高蓝莓种子萌发率,探究了蓝莓种子催芽方法。以蓝莓种子为材料,采用室温、低温和变温等3种不同温度层积处理,进行发芽试验,比较了蓝莓种子发芽情况。结果表明：不同处理条件下蓝莓种子在萌发率、发芽势、发芽指数等各项指标上差异显著(P<0.01),变温层积处理的各项萌发指标达到最优,萌发时滞11 d、萌发历期30 d、发芽率57%、发芽势48.75%、发芽指数3.49。变温层积处理能使蓝莓种子萌发时期提前,能显著增加种子的萌发率、发芽势,可以显著提高蓝莓种子的发芽指数,采取变温层积催芽方法对蓝莓种子催芽,可有效解除蓝莓种子休眠,提高种子萌发效率。     

文冠果育苗技术试验研究

本文通过混沙埋藏催芽、温水浸种催芽、快速催芽法三种方法对文冠果种子进行了催芽试验。结果表明文冠果种子催芽中,采用混沙埋藏催芽法,出苗率能达100%,在生长过程中,苗高和地径都显著优于其他催芽方式。容器育苗和插根育苗在苗高和地径方面优于播种育苗。     

红锥育苗技术

文章对红锥育苗系列技术进行了探讨，具体在种子催芽、容器苗营养土配方、幼芽与幼苗移植、不同苗床育苗等4个方面进行了对比试验。结果表明红锥种子室外沙藏催芽优于室内沙藏催芽；红锥幼苗适宜在通气良好、土壤肥力较高的苗床上生长；种子发芽后以长出真叶的幼苗阶段移植上袋成活率最高。     

光皮梾木种子催芽技术研究

采用不同的催芽方法对光皮梾木的种子进行处理,试验结果表明:光皮梾木的种子在低温沙藏120d发芽率较高,达63.4%,低温沙藏90d以后对促进种子的发芽作用显著。在湖北光皮梾种子低温沙藏催芽方法较其它催芽方法好。     

肉桂种子水洗催芽的技术及效果

为了解决肉桂种子传统沙藏催芽法发芽率低、发芽不整齐的问题,进行了水洗催芽法和沙藏催芽法试验。结果表明,两种方法的发芽率、发芽势及发芽速度均达到显著差异,水洗催芽处理的发芽率95．28％、发芽势57．63％、发芽速度12．70d,比沙藏处理分别提高25．18,5．40个百分点和提前16．47d,水洗催芽法能有效促进肉桂种子发芽率,发芽速度快,发芽整齐,并利于育苗的田间管理,降低育苗成本。     

不同处理对黄花远志种子发芽的影响

对黄花远志种子采用砂擦、赤霉素浸种、温水浸种3因素、3水平正交试验设计进行沙藏催芽对比试验。结果表明:经过处理后的种子比未经处理种子平均发芽时间早14.4 d;平均发芽率提高27.4%;温水浸种对种子发芽影响显著,赤霉素浸种、砂擦对种子发芽有一定影响;以中度砂擦+赤霉素1200倍液浸种8 h+50℃温水浸种8 h组合处理后的种子发芽率最高,达93%。     

沙棗火炕混砂催芽法

沙枣具有抗旱、耐碱、耐寒的特性,适宜于砂漠中生长,是陕北固砂造林的好树种。伹沙枣是硬核种子,发芽困难,所以在播种前需进行催芽处理。沙枣催芽法有露天埋藏和火炕混砂法两种,后者较前者效果好,表现在下列各方面:1.催芽快——火炕混砂催芽仅11天就有15%的沙枣种子露头发芽;而露天埋藏却需34     

白三叶种子催芽技术与育苗基质的研究

以白三叶(Trifoliu mrepens)种子为试验材料,研究水浸时间、育苗基质类型、不同浓度赤霉素与硝酸钾浸种处理对白三叶种子发芽的影响。结果表明,水浸24h可极显著提高种子发芽指数、萌发活力指数、发芽势和发芽率,与未浸种的相比发芽率可提高10%-13%;基质类型对种子的发芽指数和萌发活力指数影响均达到显著水平,种子较适合的催芽浓度与育苗基质组合为50mg·L-2赤霉素、0.2%硝酸钾、园土∶沙∶泥炭土=2∶1∶1,平均发芽率达31.67%,平均萌发活力指数达42.212。     

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.