利用植物体再生机能快速培育三倍体山杨

利用植物体现生机能快速培育三倍体山杨的试验结果表明,用环状切根法１棵优树上可培育３￣５株根蘖苗,山杨母条最佳栽植时间为４月１５日￣４月２０。三倍体山杨无性繁殖关键是保持旺盛的根系活力和及时培育白化茎苗。１株优良三倍体根蘖苗经过５年可培育出１０万株优良壮苗,５年后每年纯增值可达１万元。     

原地培育枣苗新法

原地培育枣苗新法枣树根蘖苗须根很少，移栽成活率低，影响了枣树的发展。山西省石楼县林业局杨海青在实践中探索总结出了“伤根截干促根法”，原地培育枣树根蘖苗，使枣树根蘖苗须根大量增加，大大提高了定植成活率。具体操作法：①对枣园萌生的一、二年生根蘖苗留１－２...     

冬枣繁育与栽培技术

为加速冬枣的繁育与栽培,及早形成较高的产量,满足人们的需要,现将冬枣繁育与栽培技术做简要的介绍。１　冬枣育苗技术１－１　砧木苗的培育采用的砧木主要有小枣根蘖苗、酸枣苗和小枣实生苗。１－１－１　根蘖苗的培育　深秋或早春,在枣园或枣树带（枣农间作）内,距树干１ｍ处,挖宽２０～３０ｃｍ,深５０～６０ｃｍ的纵沟,将直径２ｃｍ以下的根截断（保留直径２ｃｍ以上的大根）以促发根蘖苗。当根蘖苗长到１０ｃｍ高时,每墩选留一株健壮苗,其余一律除去。７月底、８月初,将苗木打顶,控制高生长,使其增粗。１－１－２　种子育…     

“三荒”、“两漠”造林树种速生槐

速生槐根系发达,根蘖力和再生能力强,水平根系延伸或断根后可萌发出新的植株,单株即可延伸成片林。将栽100株／667m^2速生槐育苗基地的苗、根挖出后,靠残留根第2年可根蘖萌生出400—500棵／667m^2新株。速生槐是有效加快荒山、荒坡、荒滩造林的速生树种。     

枣树育苗技术

枣树育苗技术省林木种苗站武红柱枣树育苗方法，目前主要有根蘖和嫁接两种。一、根蘖苗的培育（一）根蘖苗的收集培育根蘖苗要用归圃育苗法。其方法是先从大枣树下选取根蘖小苗，时间在早春枣树发芽前或晚秋落叶后，刨取５厘米～４０厘米以内的萌生枣苗。刨苗要尽量多带根...     

枣树育苗技术

枣树育苗技术山西省林科所何祥生枣树育苗方法，目前主要有根蘖和嫁接两种１．根蘖苗的培育１．１根蘖苗的收集培育根蘖苗要用归圃育苗法。其方法是先从大枣树下选取根蘖小苗。时间在早春枣树发芽前或晚秋落叶后，刨取５—４０ｃｍ以内的萌生枣苗，刨前先要搞清品种，尽量...     

平欧大榛子根蘖育苗技术

利用根蘖萌生苗覆土的办法培育平欧大榛子苗木,操作简单,成本低,效率高,1株5 a生母树可繁育苗木30～50株。     

紫薇根蘖繁殖试验

紫薇繁殖采用机械损伤侧根和截断侧根促进根蘖2种育苗措施进行繁殖,可保持母树优良品系,多出苗、育优苗、育壮苗,促进母树短气根和干生长.试验表明2种根蘖繁殖方法,以截断侧根法较好,单株母株平均出苗量为13.2株,平均苗高为85.8 cm.     

银杏根蘖苗绿枝嫁接

银杏根蘖苗绿枝嫁接在银杏育苗中，苗圃培育的大苗根基周围易抽生根蘖苗。过去多采取修枝法将其除掉，但由于修剪法不能彻底根除，根蘖还是年年抽生，影响银杏大苗主干的生长。对此，济南市苗圃采用绿枝嫁接的方法，即解决大苗根蘖根除的问题，又充分利用了这些根蘖，嫁接...     

文冠果圃地二茬苗培育技术

文冠果二茬苗培育的途径有:(1)Ⅲ级苗留床继续培育;(2)当年未萌发的种子翌年春天继续发芽出土;(3)残留在土壤里的根系萌发根蘖苗。文冠果二茬苗培育可降低育苗成本,其根蘖苗繁殖技术是良种扩繁的好方法。     

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.