不同密度、截干高和基肥对桉树采穗圃插穗产量的影响

通过正交试验设计研究了采穗圃母株定植密度、截干促萌高度及基肥种类对桉树采穗圃嫩枝插穗和硬枝插穗产穗量的影响。试验结果表明：母株以20cm×20cm定植株行距（A3）＋母株距根茎部位20cm处的截干促萌高度（B3）＋施用1125kg.hm-2发酵牛粪（C2）组合即（A3B3C2）为最佳处理组合,单株嫩枝产穗量达23.3条·年-1,单株硬枝产穗量达16.6条·年-1。     

不同截干高度下米老排促萌效果

为完善米老排 Mytilaria laosensis 采穗圃营建技术，重点探究不同截干高度对 2 年生米老排无 性系苗促萌效果的影响。试验共设置 3 种截干高度处理，即 20（T1）、30（T2）、40 cm（T3），采取主干 和萌条 2 次截干法。结果表明：第一次截干后 T2 和 T3 的萌芽数和萌条数显著大于 T1，且 T3 ＞ T2 ＞ T1， T3 平均每株萌芽数和萌条数分别达 10.72 个和 4.17 条，但 T1 的萌条转化率最高；二次截干后，各处理间 萌条数差异不显著。截干高度对萌条基径影响不显著，对二次截干后的萌条长度影响显著，但 T1 的萌条 基径均最大，其萌条质量相对来说更优。两次截干后 T1 的单位萌条数均极显著大于其他两个处理，其促 萌效果最佳，且越靠近根部的萌条，其幼态化程度也越高，分化能力越强。综合来看，截干高度 20 cm 更适合米老排的截干促萌。     

景观型木麻黄优良品种采穗圃适宜密度研究

为获得景观型木麻黄优良品种要建立采穗圃,为生产单位提供更多优良苗木,开展了木麻黄采穗圃密度试验,结果表明:圆头木麻黄为1.2m×1.2m,千头和垂柳木麻黄为1.0m×1.0m,龙柏和如意木麻黄为0.8m×0.8m较为适宜,得到的单位面积合格穗条数量及采穗可及度为最佳;圆头木麻黄截干促萌的高度为80cm,其他木麻黄高度为40cm。共培育景观型优质苗木5万株,造林成活率达90%以上,水培苗穗条采集可持续使用5年。     

金黄熊猫促萌及扦插试验研究

通过对3年生金黄熊猫(Xanthostemon chrysanthus)植株进行促萌及扦插试验,研究了不同方式促萌效果,不同高度促萌的萌条扦插效果以及穗条分段的扦插效果,结果表明,对于分枝较多的植株于早春进行顶梢摘心可促发较多萌条,且萌条生长快,短期可获得大量穗条用于扦插。其次,主干30cm处截干促萌的萌条数量高于其他处理,且中部截干所抽发的萌条生根率高,可达86%,不同高度促萌的萌条扦插生根率由高到依次为中部>下部>上部,穗条分段扦插对扦插效果影响不大。     

香椿木本蔬菜林试验初获成效

香椿芽香气浓郁,含有大量的维生素 C和多种营养物质,是广大城乡人民喜食的一种木本蔬菜。随着人民生活水平不断提高,对香椿的需求量越来越大。为了发展香椿生产,满足市场需要,从1986年开始,我们与洪洞县华林苗圃协作开展了营造香椿木本蔬菜林试验,收到了较好的效果。1 造林香椿蔬菜林建于洪洞县华林苗圃内,造林用苗系由该圃培育的2年生香椿苗,苗高1.0～1.5m,地径1.5～2.0cm。栽植坑规格0.3m×0.3m×0.5m。株行距1.0m×1.0m、0.8m×1.0m 和0.5m×1.0m 三种规格。2 管理2.1 截干为了便于经营管理和采摘香椿,我们采取了截干措施,既降低高度,又促使多萌侧枝。截干高度有0.1m、0.5m、1.0m 和2.0m4种。     

杉木采穗圃的营建及管理技术研究

通过试验研究杉木采穗圃母株不同定植株行距、母株距根茎处不同截干促萌高度及圃地施用不同种类的基肥对母株产穗量的影响,结果表明:杉木母株定植株行距20 cm×20 cm+母株距根茎部位15 cm处截干+施用1 050 kg.hm-2硫酸钾复合肥作基肥(A3B3C2)组合产穗量最高,母株嫩枝单株年平均产穗量18.8穗,母株硬枝单株年平均产穗量15.9穗。     

合欢幼苗截干当年萌条生长量与截干高度、米干径相关规律研究

通过对同一截干高度(3.2m),不同米径的合欢幼苗;及对同一米径粗度(4cm),不同截干高度的合欢幼苗,当年萌条生长量观测发现:前者为正相关,后者为负相关。米径4cm的合欢,截干高度应在2.5~3.2m间为宜,米径大于4cm的合欢,截干高度应适当增加,米径小于4cm的合欢,可适当降低截干高度。     

叶用银杏园丰产栽培技术研究

为了探讨提高银杏专用采叶园产量的技术措施 ,对大佛指 2年生实生苗分别进行了不同的截干高度、留萌条数、密度及配方施肥处理。研究结果表明 :(1)截干、留萌条数单因子最高产量效应分别为平地定干和留 4根萌条 ,优化组合措施为平地定干并留 3根萌条 ;(2 ) 4种密度配置中 ,单位面积产量最高的密度设置为 40cm× 5 0cm ;(3)钾肥的产量效应不显著 ,氮、磷单施和配施都具有不同的增产效果 ,据拟合的氮 磷产量效应方程 ,提出了氮磷肥的合理施用量。     

核桃楸紫椴不同造林密度的试验研究

通过10年6种密度造林试验研究结果表明,核桃楸和紫板的初植密度均以1.5m×1.5m为最佳。造林后10年其胸径、树高、蓄积量均高于其它密度;成活率、保存率高;自然整枝好,干冠结构合理。     

阔叶树种雨季植苗造林技术试验

用选出的阔叶树种,选用不同年龄的苗木,在雨季对苗木进行截干处理后,作植苗造林试验。结果表明用1.5a生苗木和2.5a生苗木,截干后植苗造林效果较好。     

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。     

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.     

Key Habitats in the Norwegian Production Forest: A Case Study

This study investigated the forest history, structural characteristics, the presence of fungal species suggested to indicate ecological continuity in old-growth forest, and the species composition of saproxylic beetles in 30 old forest ''woodland key habitats'' (WKHs), and compared them with production forest in the same age-class in south-eastern Norway. No statistically significant differences in forest characteristics, community of saproxylic beetles or number of red-listed beetles were found between the WKHs and the production forest, probably owing to a combination of profound long-term logging and a lack of will to delineate sufficiently large WKHs in the one area with significantly less forestry impact. The study indicates the advantage of including forest history information in WKH selection where such data exist, and the importance of restoring habitats in heavily exploited forest landscapes.