不同营养水平对黎蒴栲容器苗生长的影响

对黎蒴栲容器实生苗进行不同浓度、频率的施肥试验,测定其生长指标,旨在揭示黎蒴栲容器实生苗生长对复合肥肥料的需求,确定其适宜施肥量和频率。结果表明:黎蒴栲容器苗施肥处理均比对照生长好,而复合肥施用质量浓度为0.4%、施用频率14天,以及施肥质量浓度1.0%、施用频率21天,苗木生长好且培育成本低。     

施肥对黎蒴栲幼苗叶绿素含量的影响

为了探讨苗期施肥对黎蒴栲叶片叶绿素含量的影响,采用均匀设计对黎蒴栲实生幼苗进行不同梯度的配比施肥试验。结果表明:施肥处理T_4(N 0.112 5 g/株、K_2O 0.050 0 g/株)、T_5(N 0.075 0 g/株、P_2O_5 0.350 0 g/株)均较有利于黎蒴栲幼苗的生长。施氮肥处理的黎蒴栲苗木叶片叶绿素a、叶绿素b、总叶绿素含量均高于未施氮肥处理(T_3,P_2O_5 0.175 0 g/株、K_2O 0.100 0 g/株)和对照的,施氮肥有利于黎蒴栲幼苗叶片叶绿素的积累。黎蒴栲叶片叶绿素含量在施肥前期,与氮肥施用量呈正相关;后期生长阶段,叶片叶绿素含量与其生长状况密切相关。可通过叶片叶绿素含量了解植物对氮肥的需求情况。     

4年生黎蒴栲工业原料林的地形因子效应

对4年生黎蒴栲工业原料林在不同坡位、不同坡向及不同坡形的生长表现进行调查分析,结果表明:不同坡位对黎蒴栲生长的影响比较大,下坡位的生长最好,中坡位次之,上坡位最差;不同坡向对黎蒴栲生长的影响,呈现出阴坡的生长最好,半阴坡次之,半阳坡和阳坡的生长稍差;坡形对黎蒴栲生长的影响,凹形坡的平均胸径、平均树高和平均冠幅显著好于凸形坡和斜形坡,凸形坡和斜形坡之间的差异不明显。     

珍贵红木树种囊状紫檀容器育苗试验

以培育6月苗龄囊状紫檀容器苗为对象,采用正交试验设计方法开展容器规格、肥料种类和育苗基质对苗木各指标生长的影响研究.结果表明,随着育苗容器规格的增大,苗木的各项指标的生长量明显增多.施5％有机肥的苗高和地下部分的干重明显优于施2％磷肥和1％复合肥,但三者间的地径、主根长、地上部分干重及全株生物量差异不显著.采用80％森林土+20％火烧土的育苗基质培育的容器苗生长表现最好.对不同因素、不同水平的各个组合处理进行分析,6月生囊状紫檀的容器育苗最佳组合为12 cm×16 cm(或9 cm×12 cm)的容器规格,施用2％的磷肥作为基肥,采用80％森林土+20％的火烧土作为育苗基质.     

不同基肥对柚木容器苗生长的影响

通过在黄心土中按一定质量比添加不同基肥进行柚木容器苗育苗试验,结果表明,在黄心土中添加1%～5%经过堆沤的桐麸或猪粪苗木生长都比较好,综合苗木生长情况、基肥材料来源和经济等因素考虑,认为柚木容器育苗生产上使用的最佳基肥配比应是97%红心土+3%经过堆沤的猪粪。     

容器类型和规格对油松容器苗生长的影响

通过采用不同类型和规格的容器进行油松育苗试验,测定了1年生长期后油松容器苗的苗高、地径、主根长和总根长等生长指标,分析不同容器类型和规格对油松容器苗生长的影响。结果有明:苗高和地径以硬塑料容器处理最大,分别达到了15.5cm和2.66mm;苗木主根长以小规格黑色塑料容器处理最大,达到29.8cm;苗木根系总长以大规格黑色塑料容器最大,达到740.4cm。可见,硬塑料容器有利于油松容器苗地上部分生长,黑色塑料容器对容器苗根系生长促进效果更好。     

伤流等指标评价在尾叶桉容器苗质量中的应用

测定了不同基质的尾叶桉容器苗的伤流、叶绿素含量、苗高、生物量、高径比等指标.结果表明:伤流的测定值和苗木的其它常用指标相一致;生长状况好的苗木伤流量大,表明伤流用于评价尾叶桉苗木的生活力,选择适合的容器育苗基质是可行的;同时选出了以蔗渣和木屑为主要原料的尾叶桉容器苗优良育苗基质及其处理方法.     

菌肥对香榧等控根容器苗生长的影响

在香榧、山核桃、杨梅等控根容器苗培育过程中,选用固氮菌、解磷菌及其混合菌进行菌肥试验。结果表明:施菌肥3 a后,香榧容器苗解磷菌、混合菌处理苗高生长量比对照分别增加18.26%和18.06%,差异显著(P<0.05);山核桃容器苗固氮菌、混合菌处理高生长量比对照分别增加46.25%和47.23%,差异显著(P<0.05);杨梅容器苗混合菌处理苗高生长量与对照相比差异显著(P<0.05),明显优于它们单独使用效果;此外,不同菌肥对香榧等3种苗木地径生长也有一定的促进作用。由于不同的菌肥对各树种的苗木生长促进效果有明显差异,在苗木培育过程中,应根据不同的苗木合理选用菌肥。     

乐东拟单性木兰容器大苗培育技术研究

研究了基质配比、基肥种类和施肥量、容器规格对3年生乐东拟单性木兰(Parakmeria lotungensis)容器大苗生长的影响,结果表明:乐东拟单性木兰容器大苗对不同基质配比的生长反应差异很大,以珍珠岩为主的配比基质容器苗生长表现最优,以沤制后谷壳为主的轻基质苗木生长较好;不同基肥种类及施肥量对容器苗生长影响显著,施用爱贝斯长效缓释肥(N:P:K=18:18:8)的容器苗生长表现最好;容器规格对乐东拟单性木兰容器苗生长影响显著,容器规格的增大可显著促进苗高和地径生长。从苗木质量和育苗成本等因素综合考虑,乐东拟单性木兰轻基质容器大苗优良培养方案为:基质配比(体积比)为泥炭:黄泥:谷壳=2:3:5,基质中施用3.0 kg/m3爱贝斯长效缓释肥,无纺布容器规格为D×H=30 cm×30 cm。     

不同营养条件对黎蒴栲幼苗形态指标的影响

采用均匀设计对黎蒴栲实生幼苗进行不同梯度的N、P、K配比施肥试验,探讨不同营养条件对黎蒴栲幼苗苗高、地径、冠幅的影响。结果表明:1)不同营养条件对黎蒴栲幼苗的形态指标有很明显的影响。T5(N:0.075 0 g/株、P2O5:0.350 0 g/株)施肥处理的苗高、地径、冠幅较大,其次为T4(N:0.112 5 g/株、K2O:0.050 0 g/株)、T3(P2O5:0.175 0 g/株、K2O:0.100 0 g/株)施肥处理,T1(N:0.150 0 g/株、P2O5:0.262 5 g/株、K2O:0.150 0 g/株)、T2(N:0.037 5 g/株、P2O5:0.087 5 g/株、K2O:0.200 0 g/株)施肥处理和对照则较差。2)N、P、K对黎蒴栲幼苗生长的影响效应各不相同。氮肥可促进黎蒴栲幼苗的生长,但过多的钾肥则不利于黎蒴栲幼苗的生长。     

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.