闽楠播种芽苗不同移栽密度生长效果分析

采用闽楠播种芽苗设计3种不同移栽密度(株行距8cm×8cm、10cm×10cm、10cm×15cm)进行试验,比较闽楠一年生播种芽苗的生长量及苗木质量。结果表明:移栽密度以株行距10cm×15cm较适宜,苗木生长量最大,苗木质量最优,平均苗高、平均地径、平均主根长度、≥5cm长Ⅰ级侧根平均条数、平均合格苗率、平均合格苗产量分别达47.2cm、0.45cm、24.5cm、21.4条/株、97.0%、65.04万株/hm2。     

榉树自然下种苗培育试验

为发掘榉树良种资源,用优良家系林内的自然下种幼苗,研究不同移植密度、圃地条件对苗木生长的影响及培育技术。结果表明,1年生苗高101.1cm、地径1.09cm,Ⅰ、Ⅱ级苗出圃率达77%,分别比春季播种育苗增加13.21%和29.76%。苗木质量也优于春播苗,提高11%。育苗收入和净利润分别比春播苗增加9.89%和31.52%。地势高、排水良好的沙质土壤圃地1年生苗高和地径生长量分别比地势低洼、土质较黏重、排水不畅圃地高25.83%和8.33%,Ⅰ、Ⅱ级苗出圃率增加21%。供试3种移植密度的苗高生长排序为:15cm×15cm>10cm×15cm>5cm×10cm。15cm×15cm密度移植自然下种苗能培育较多健壮苗木。试验共移植培育40万株自然下种苗,3年生时(移后2a)平均树高3.36m,地径4.3cm,显示出可观的应用潜力。研究结果为榉树优良家系良种壮苗扩繁推广提供了科学依据。     

榉树自然下种苗培育试验

为发掘榉树良种资源,用优良家系林内的自然下种幼苗,研究不同移植密度、圃地条件对苗木生长的影响及培育技术。结果表明,1年生苗高101.1cm、地径1.09cm,Ⅰ、Ⅱ级苗出圃率达77%,分别比春季播种育苗增加13.21%和29.76%。苗木质量也优于春播苗,提高11%。育苗收入和净利润分别比春播苗增加9.89%和31.52%。地势高、排水良好的沙质土壤圃地1年生苗高和地径生长量分别比地势低洼、土质较黏重、排水不畅圃地高25.83%和8.33%,Ⅰ、Ⅱ级苗出圃率增加21%。供试3种移植密度的苗高生长排序为:15cm×15cm10cm×15cm5cm×10cm。15cm×15cm密度移植自然下种苗能培育较多健壮苗木。试验共移植培育40万株自然下种苗,3年生时(移后2a)平均树高3.36m,地径4.3cm,显示出可观的应用潜力。研究结果为榉树优良家系良种壮苗扩繁推广提供了科学依据。     

鹅掌楸播种芽苗不同移栽时期和密度对苗木生长的影响

采用鹅掌楸种子播种培育芽苗,进行了不同移栽时期(种子发芽出苗第2 d、第4 d、第6 d、第8 d、第10 d)成活率比较试验和芽苗不同移栽密度(株行距15 cm×20 cm、20 cm×20 cm、20 cm×25 cm)苗木生长效果比较试验,结果表明：鹅掌楸播种芽苗移栽时期在种子发芽出苗后第2～4 d移栽效果最好,成活率分别达97.3%、94.7%,随着移栽时间的延迟,成活率逐渐降低;移栽密度以株行距20 cm×20 cm最为适宜,苗木总体生长较均衡,平均合格苗率、平均合格苗产量最高,分别达89.3%、0.893万株/666.7 m²,苗木的平均地径、平均苗高、平均主根长度、≥5 cm长Ⅰ级侧根平均条数分别达0.99 cm, 97.8 cm, 31.2 cm、9.7条/株。     

棕榈不同播种密度对苗木产量和质量的影响

通过对棕榈播种密度为10 cm×10 cm、15 cm×15 cm、20 cm×20 cm、25 cm×25 cm、30 cm×30 cm、35 cm×35 cm几种类型进行育苗试验,得出密度类型20 cm×20 cm合格苗产量最大,达到10 005株/667m2;播种密度25 cm×25 cm时苗木合格率最高,当密度大于和小于25 cm×25 cm时,合格率均呈下降趋势,当密度逐步大于25 cm×25 cm时,死亡率呈逐步上升的趋势;用播种密度25 cm×25 cm合格苗木造林,幼林林相最为整齐。     

移植对木荷轻基质容器苗生长的影响

为探讨移植、营养袋规格、株行距等对木荷一年生轻基质容器苗生长的影响,在苗床中采用袋深10 cm、直径分别为4.5 cm、5.5 cm、6.5 cm的3种规格轻基质营养袋开展移植与不移植试验,在移植试验中设置了9 cm×9 cm、11 cm×11 cm、13 cm×13 cm等3种株行距。结果表明,移植后的木荷轻基质容器苗平均苗高、地径、成活率、合格苗率、合格苗产量比未移植的有显著提高,高径比显著降低;培养1 a苗龄轻基质容器苗,使用直径5.5 m、深10 cm的营养袋基质,按11 m×11 cm的株行距移植,不但可以提高合格苗产量,而且育苗的投入产出比更加合理。     

猴欢喜播种芽苗不同移栽密度生长效果分析

试验采用猴欢喜播种芽苗进行苗床不同移栽密度的生长量和苗木质量、产量比较。结果表明:不同密度的生长量以株行距15cm×15cm最大,平均地径达0.62cm,平均苗高达36.4cm,平均主根长度达30.9cm,≥5cm长Ⅰ级侧根平均条数达10.9条。苗木产量和质量控制指标以株行距15cm×15cm密度较适宜,达1.77万株/667m2,培育的苗木质量较好。     

营养袋两段育苗及基质配方优化技术在喜树育苗上的应用

通过总结多年营养袋育苗技术，研究得出先将种子培育成子叶苗，再移植到营养袋中进行培育的两段育苗技术。利用二次旋转正交组合设计方法对育苗基质配方进行优化。使喜树一、二级苗和合格苗比播种苗分别提高3．6％、24．3％和27．9％，造林成活率比播种苗提高10．9％。并具有节约投资和用工量。     

竹柏不同播种育苗方式的生长效果分析

采用容器(10 cm×10 cm营养钵)和田间苗床2种播种育苗方式,进行了竹柏不同播种密度、不同遮荫处理的比较试验,结果表明:2种育苗方式对竹柏种子的发芽率没有显著影响,田间苗床播种苗的生长量大于容器苗;田间苗床的播种密度以株行距10 cm×20 cm最为适宜,生长量最大;生长期遮荫对竹柏播种苗有极显著影响,遮荫处理的苗木保存率达92.3%,未遮荫的苗木保存率只有37.5%。     

珍珠绣线菊育苗技术

对珍珠绣线菊1 a生播种苗进行垄作移植育苗,每3~4株栽于一穴,在距根际5~8 cm处截断苗茎,依靠其萌蘖能力培育丛状苗;平均高度为76 cm,地径为0.4 cm及以上,基本可满足工程使用需要。     

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.