沙地云杉生态型表观性状分化

沙地云杉为内蒙古特有树种,干旱适应性强,已成为我国西部重要造林树种。在长期适应干旱生态条件的过程中沙地云杉形成了紫果型、绿果型和红果型等多种生态型。文章对各种生态型沙地云杉的表观性状分化进行了比较研究,可为沙地云杉生态型分化机理研究提供理论参考,对扩大沙地云杉造林面积和西部大开发的生态环境建设具有重要的指导意义。     

呼伦贝尔沙地引种沙地云杉初报

2007年从内蒙古赤峰引种2年生沙地云杉(Picea mongolica)裸根苗并定植在呼伦贝尔市鄂温克旗中心苗圃。2012年春季,分别在半固定沙地和流动沙地进行造林试验,对沙地云杉成活率、保存率、生长量进行观测。结果表明,沙地云杉在呼伦贝尔沙地生长正常,在半固定、流动沙地上的平均存活率达92.5%,年平均高生长量达12.1cm,保存率达86%以上,初步确定沙地云杉在呼伦贝尔沙地可以进行引种造林。     

沙地云杉沙地造林技术的研究

通过在沙地进行沙地云杉造林试验表明:沙丘的阴坡比阳坡造林成活率高21.7个百分点,植被盖度较小的立地比植被盖度高的立地造林成活率高30%左右.采用座水覆膜和容器苗造林分别比对照提高造林成活率29.4个百分点和35.5个百分点.并形成沙地云杉在沙地配套的造林技术.     

沙地云杉研究进展与展望

天然分布在浑善达克沙地的沙地云杉林以其独特的生物学特性引人注目,诸多研究者重点在分类地位、育苗造林技术等方面开展了研究。本文综述了沙地云杉分类、天然更新、育苗造林、抗逆性和菌根相关研究成果,为进一步开展沙地云杉研究提供参考。     

不同方法提取三种生态型沙地云杉总DNA的比较

沙地云杉为内蒙古特有树种,干旱适应性强,是我国西部重要造林树种。在长期适应干旱生态条件的过程中沙地云杉形成了紫果型、绿果型和红果型3种生态型。前期研究证明:紫果型沙地云杉有更强的抗旱能力,绿果型抗旱能力弱,红果型处于二者之间,是一个比较典型的过渡类型。本文从分子生物学的角度,详细叙述了沙地云杉总DNA的提取过程、方法,并对已知的植物DNA提取方法作了针对性的改良;对实验过程提取DNA的影响作了分析。为今后针对进行沙地云杉的植物基因研究和生物工程打下基础,对扩大沙地云杉造林面积和西部大开发的生态环境建设具有重要的指导意义。     

沙地云杉引种实验

沙地云杉是我国珍稀濒危树种,为了扩大这一树种的造林范围,2003年将其树种从内蒙古克什克腾旗的白音敖包引种到呼和浩特,对其适应性进行了观察。结果表明:沙地云杉在呼和浩特市生长正常,两年高生长达6.73 cm,物候期比原产地提前30d,保存率为35.5%,因此沙地云杉有引种成功的可能性。     

半干旱地区沙地云杉播种育苗试验

沙地云杉为沙地造林常用的一个树种。通过开展沙地云杉播种育苗试验,研究了播种方式、播种时间、遮阴方式等对沙地云杉播种出苗量及生长情况的影响。结果表明:早播种、高床、遮阴有利于苗木地径、苗高的生长;影响苗木地径生长的主要因素是地面温度、最高温度、15cm土层温度;影响苗高的主要因素为地面温度、地面最高温度、20cm土层温度。     

沙地云杉容器苗强化育苗技术

沙地云杉(Picea mongolica)是内蒙古浑善达克沙地特有的针叶乡土树种,也是我国特有的树种。是沙地造林的首选树种之一。本文详细介绍了沙地云杉的种子处理、基质、容器、播种、补充光照、施肥、病害预防、苗期管理、苗木出圃等技术要求,得出容器出苗率达到92.5%,当年年底苗木成活率达到89.2%;经过强化培育3a,容器苗平均苗高达到21.2cm,造林成活率达到91.5%。     

沙地云杉种子萌发特性研究

为探索沙地云杉种子萌发特性,研究了温度、光照、浸种时间、赤霉素浓度对沙地云杉种子萌发的影响。结果表明：沙地云杉种子最适发芽温度为25℃,发芽率为80.00%。15℃、20℃和30℃温度条件下,种子发芽率显著降低。在有无光照的条件下沙地云杉种子均可萌发,但全光照和光照-黑暗条件下发芽率显著高于全黑暗条件,说明适当光照有利于沙地云杉种子萌发。浸种12 h可在萌发初期显著提高种子的发芽率,但是与对照相比,12～48 h浸种处理在发芽期结束时均未能显著提高种子的发芽率。低浓度的赤霉素对沙地云杉种子萌发有促进作用,用100 mg·L^-1赤霉素处理12 h,种子发芽率可达81.33%。     

干旱荒漠区沙地云杉幼苗越冬措施效果分析

在干旱荒漠区,对1年生沙地云杉容器苗在温室和自然条件下分别设置实验,对其越冬措施效果进行了比较分析。在室外条件下对沙地云杉幼苗采用土壤、沙子、塑料、塑料薄膜、麦草、树叶为覆盖材料,同时,对沙地云杉埋土越冬采用了土壤、沙子2种材料,设置了不同的覆盖厚度。研究不同覆盖材料和覆盖厚度对苗木越冬保苗率的影响。研究结果表明:(1)覆土对沙地云杉幼苗的保苗率明显高于覆沙的保苗率,覆土厚度与保苗率关系密切(R2=0.916 4),覆土的厚度为10~15 cm保苗效果最好;(2)各种覆盖材料相比,覆土对沙地云杉幼苗越冬效果最好。     

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.