沙枣2种育苗技术效果对比试验

通过对沙枣进行扦插育苗和播种育苗试验,分析了2种育苗方法的效果,结果表明:沙枣扦插育苗苗木成活率65.0%,当年平均高生长量和地径生长量分别为58 cm和0.63 cm,第2年平均高生长量和地径生长量分别为104 cm和1.08 cm。春秋季种子育苗苗木出苗率分别为75.5%和93.5%,春季育苗当年平均高生长量和地径生长量分别为38 cm和0.37 cm,第2年平均高生长量和地径生长量分别为97 cm和0.86 cm;秋季播种1年生平均高生长量和地径生长量分别为40 cm和0.38 cm,第2年平均高生长量和地径生长量分别达到95 cm和0.87 cm。沙枣播种育苗出苗率高,单位面积载苗量大,经济效益高。     

武当木兰种子繁殖研究

采用正交试验设计方法对武当木兰种子育苗技术进行了研究，结果表明：提高武当木兰播种育苗的最佳培养方案为：混沙土、覆土厚度1．5cm，用塑料薄膜覆盖，出苗率最高，苗木生长量最好。     

覆盖基质及播种时间对白皮松出苗的影响

在相同的整地、种子处理、播种方式、苗期管理与病虫害防治措施的情况下，研究不同覆盖基质及播种时间对白皮松出苗及苗木生长的影响。结果表明：1）白皮松播种育苗选用腐殖质土作为覆盖基质出苗率最高，达93％；感病率最低，仅为6．5％；高生长量最大，达5．6cm。2）在吕梁山南端白皮松播种时间为5月5日前后较为适宜，出苗整齐，出苗率高。     

沙荒地文冠果播种育苗技术试验研究

针对沙荒地文冠果种子育苗存在的出苗率低、出苗不整齐、苗木质量差等问题,选择播种时期、覆盖方式、种子处理方法、播种方式4个影响因素作不同处理组合对比试验分析,结果表明：春季文冠果种子育苗以4月25日播种,采用覆膜＋沙覆盖方式,种子高温催芽,覆膜点播的组合方式最佳,其出苗率和生长量明显高于春播的其他处理组合,是沙荒地文冠果春季播种比较理想的组合方式;秋季育苗其出苗率比春播处理组合平均高22.8%,苗木地径比春播平均高31.6%,即10月28日播种,采用土覆盖,种子不处理,开沟条播的处理组合是秋季文冠果沙荒地育苗的最佳选择。     

南方红豆杉芽苗容器移栽育苗技术

对南方红豆杉芽苗容器移栽育苗进行了试验,结果表明:芽苗容器移栽育苗技术较以往传统方法播种育苗出苗率高,节约种子及土地资源,苗木质量好,产苗量高,能明显延长苗木的生长期,苗木当年平均生长量可达15cm。     

苗床覆盖物对紫斑牡丹播种苗出苗率的影响

紫斑牡丹繁殖多以分株、种子、嫁接3种育苗方式。种子播种育苗能大面积成规模培育出需要的牡丹苗木,而且育苗成本较低。在高海拔冷凉阴湿地区紫斑牡丹种子育苗,一定要塑料拱棚加育苗床的覆盖,育苗床覆盖能大幅提高出苗率。在苗床的覆盖物中清洁河沙最好、锯末次之、芥壳最差。     

不同地表覆盖物对南方红豆杉大田播种育苗效果的影响

采用完全随机区组设计,对3种覆盖条件（切碎稻草、新鲜苔藓和地膜）下,南方红豆杉大田播种育苗苗木的种子出苗率、苗木保存率、苗高生长及地径生长的情况进行了研究.结果表明：3种不同覆盖条件对种子出苗率、苗木保存率、苗高和地径的影响从优到劣的顺序均为苔藓覆盖＞地膜覆盖＞稻草覆盖.不同圃地覆盖物对苗木的苗高生长产生了极显著的影响.新鲜苔藓覆盖下苗高生长最大,达到26.1 cm;而切碎稻草覆盖下苗高生长最小,为18.4 cm.不同圃地覆盖物对苗木的地径生长产生了显著的影响.新鲜苔藓覆盖下地径生长最大,达0.55 cm;而切碎稻草覆盖下地径生长最小,仅达0.43 cm.综合分析可知,新鲜苔藓是南方红豆杉大田播种育苗的首选覆盖物.     

武当玉兰播种育苗试验

采用正交试验设计研究了武当玉兰播种育苗方法,结果表明:提高武当玉兰播种育苗的最佳培养方案为:混沙土,覆土厚度1.5cm,用塑料薄膜覆盖。出苗率最高,苗木生长量最大。为该树种在陇东南地区大量繁殖提供参考。     

覆盖方式和密度控制对檫树大田育苗的影响探讨

在檫树育苗过程中,通过设置不同的覆盖方式和播种密度,研究了其对檫树苗木生长的影响。结果表明:采取稻草+无纺布的覆盖方式出苗率最高,可以达到53.5%,效果好于单一稻草和无纺布的覆盖方式。播种密度以8cm×8cm综合效果最好,合格苗产量可达81.28万株/hm2,合格苗率可达86.7%。因此,实际生产中应采取合适的苗木覆盖方式和合理的种植密度,可以有效地提高檫树的出苗率和合格苗的产量。     

香花槐根插育苗技术研究

以插穗粗度、长度和扦插方式为试验因素,采用正交试验设计方法对香花槐根插育苗技术进行了研究,结果表明：提高香花槐根插育苗的最佳培养方案为：根系粗度0．6～1．0cm、长度15～20cm,扦插方式为斜插,出苗率最高,苗木生长量最好。     

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.