马尾松大田育苗种苗调控技术研究

通过种子分级播种，控制苗木密度，生长期切根与剪顶等综合性的试验研究，使马尾松大田苗达到了优质苗的质量指标：（１）每公顷产优质苗１００－１２０万株，Ｉ级苗率达８０％以上；（２）苗木茎干粗壮，高径比为６０－７０；（３）苗木根系发达，冠根比为４－５，（４）苗木须根数量多，菌根感染率高，在相同的田间管理条件下，所采用的４项技术措施，对培育大田优势苗各有相应的促进作用，其中以切根技术尤为突出，切根苗的高径比     

马尾松大田育苗切根技术研究

研究结果表明，在生长季节对苗木施行切根，对提高苗木质量的效应是十分明显的，通过切根，苗木茎干粗壮，根系发达，高径比与冠根比达到优质苗的比值，苗木须根数量多，菌根感染率高，优质苗率达８０％以上，为了尽快地推广，应用切根技术，同时还研制了手工操作苗木切根铲，该铲经过近两年生产应用验证，实用性强，效果好，适于松苗切根。     

马尾松切根、菌根化容器育苗效果的试验

对马尾松切根、菌根化容器育苗效果的试验表明：催芽切根的苗木的主根和高生长受到一定抑制，但地径生长、侧根发育及须根数量均有显著改善，并且避免了畸形根系的产生，从而提高了容器苗的规格质量；切根茵根化的苗木高、径生长和生物量积累均优于切根未接种菌根的苗木，幼苗造林成活串和幼林生长发育状况也明显比对照要好。     

黄山松大田苗切根培育技术研究

在寿宁县坑底乡小东村进行黄山松大田苗切根培育技术试验,结果表明：切根对苗木的高生长影响不显著,但合理的切根技术可以在一定程度上促进径粗生长与根系发达,显著提高菌根感染率,使苗木达到优质壮苗标准,显著提高造林成活率。育苗以苗高12cm左右,选择阴天在床面以下7cm处切根育苗技术的效果最佳。     

落叶松切根苗对造林成活率的影响

落叶松幼苗切根培育,春季土壤解冻15cm左右时,对1a年生苗木进行切根处理,用切根机在苗木根部15cm处切断,抑制了2a生苗的高生长,提高了径生长,缩小了苗木高径比例,促进了毛细根的发育,形成了"矮胖子,大胡子"式优质壮苗,经试验,用切根苗造林成活率比自然苗提高10%～20%。     

容器苗切断胚根的试验研究

容器苗切根育苗试验结果表明:催芽切根苗木的主根和高生长受到一定程度的抑制,但地径、侧根生长发育、须根数量及根系含水均有显著改善,并避免了苗木的畸形,切根容器苗的规格质量明显优于对照,造林成活率也比对照有显著提高。     

芽苗切根移植对南酸枣苗木及造林当年生长的影响

在贵州三都进行了芽苗切根移植育苗对南酸枣1年生苗木及造林当年生长效应的研究,结果表明:1)芽苗切根移植育苗能提高苗木单株和群体质量,与常规育苗相比,芽苗切根移植育苗对苗木径生长量的提高、长5cm的侧根数量的增加及地径标准差的降低达极显著水平,对苗木高生长的提高和对高径比值、苗高标准差的降低达显著水平;2)芽苗切根移植苗造林优于常规苗造林,当年生树高、胸径生长差异达极显著水平;3)芽苗切根移植苗的高径生长节律与常规育苗一致,但各个时期的苗木高、径生长速度有差异,主要表现为缓慢生长期比常规育苗慢,快速生长期又比常规育苗快,径生长尤其突出。     

国外针叶树切根育苗技术

为了克服传统的针叶树育苗中存在的问题，国外的许多国家对切根育苗技术进行了多年的试验，研究表明，切根苗在抗性、造林成活率和幼苗期的生长量等方面好于移植苗。切根苗的育苗密度为每平方米２００～２５０ 株；初次切根时间在土温最适宜苗木根系生长的６～７ 月，切主根长度以８～１２ｃｍ 为好；振荡在切主根后的每３～４ 周进行一次，深度以１５ｃｍ 最好。切侧根７ 月末至８ 月初，通过切根技术可培育出根系发达的优质苗木，解决了留床苗、移植苗中存在的苗木质量差和窝根的弊病。     

松类育苗二次切根

松类育苗二次切根江西省宜黄县造林项目办刘克潮等１９９３年用人工简易切根器在苗期对芽苗切根移栽培育的火炬松苗木进行了第二次切根试验。和芽苗切根苗比较，苗高下降１７．３％，地径增加４．３％，侧、须根数增加１４３．３％，侧须根长增加８６．４％，根重增加２６...     

松类育苗苗期二次切根试验初报

通过应用自行研制的人工简易切根器对火炬松芽苗切根移栽苗木苗期二次切根试验表明，切根时间以８月份为宜，切根深度以８ｃｍ为宜。二次切根苗比芽移切根苗苗高下降１７．３％，地径增加４．３％，侧、须根数增加１４３．３％，侧须根长增加８６．４％，根重增加２６．７％。应用二次切根苗木造林比对照苗成活率提高１６．２％，１年生林不当年抽高生长提高１６．２％。应用该种切根器每天可切根０．０６７～０．０８ｈｍ２。     

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.