光箨篌竹物候学的初步研究

采用固定样地竹株的观测和林分整体物候变化观测相结合的方法,分析了出笋成竹期、竹笋幼竹形成期、脱箨期、落(展)叶期、分枝期、梢部下垂期与单株、林分群体的关系以及气象因素对它们的影响,在建立光箨篌竹年物候谱基础上,将年生育划分为萌芽孕笋期、出笋成竹期、竹笋幼竹形成期和行鞭成芽期4个时期,并阐述了各时期的特点。     

光箨篌竹出笋成竹规律的研究

采用固定样地观测和随机样地调查相结合的方法,分析了光箨篌竹的出笋成竹规律以及不同径级竹笋和不同密度林分的出笋变化规律,进而分析了气象要素、立地条件和林分结构对出笋质量的影响,上述研究结果将为短周期工业用竹林的营建与培育提供依据。     

光箨篌竹竹笋幼竹生长规律的研究

对24株固定竹笋定时观测材料进行分析,表明了光箨篌竹竹笋幼竹的一些生长节律,阐述了出土期、生长级、林分密度和气象要素对竹笋成竹的影响,进而揭示了时进程类型与天气、气温和湿度的关系,探讨了它们在生产中的应用。     

苦竹出笋成竹规律的研究

对苦竹从出笋至成竹进行观察研究。结果表明：①出笋期可划分为初期、盛期、弱期和末期四个阶段。②竹杆高生长发育划分为四个时期，即生长初期、上升期、旺盛期和末期。③竹笋高生长停止后，竹杆开始抽枝、发叶、平均抽枝时间为19天，平均发叶时间为23天，竹笋从出土至成竹平均生长需98天。     

小佛肚竹抽枝长叶与竹叶凋落规律研究

通过对观赏竹种小佛肚竹抽枝长叶和竹叶凋落规律的观测研究,结果表明:8月中旬前出笋新竹当年完成抽枝,平均抽枝持续期25 d,以后出笋新竹至翌年4月下旬完成抽枝,抽枝持续期12~171 d。各出笋时期的新竹从竹笋出土至始抽枝的时间差异明显。8月下旬前、8月下旬~9月上旬、9月上旬后出笋新竹,抽枝持续期在时间阶段间差异显著,而时间阶段内差异不显著;8月中旬前出笋新竹当年完成长叶,其后出笋新竹至翌年5月上旬完成长叶,各时期出笋新竹长叶持续期无显著差异,平均12 d;抽枝长叶期23~182 d,总体呈迟出竹笋抽枝长叶期短的规律;不同季节间竹叶凋落量差异显著,以10~12月份最多,4~6月份最少,新叶抽发量以4~6月份最多。     

北京地区早园竹高生长规律及出笋长竹期的养护技术

本文以北京地区生长的早园竹（Phyllostachys propinqua）为研究对象,调查了早园竹的高度生长及竹林出笋规律。结果表明：竹笋的出笋时间不同,其成竹率也不同。出笋早的竹笋的成竹率较高;出笋越晚,竹笋的成竹率越低。据此可将早园竹的出笋期分为3个阶段：前期,中期,后期。3个阶段的时间大致相等,约为6-7d。前期笋的高生长期长、后期笋的高生长期短,它们高生长期的结束时间基本一致。早园竹的高生长遵循“慢一快一慢”规律,竹笋破土后14d和36d左右是高生长期的2个转折点,由此可将早园竹的高生长分为始期、盛期、末期3个阶段。早园竹的日最大高度生长量为51～75cm,占成竹平均高度的6．96％～9．04％。同时对早园竹出笋长竹期的养护技术进行了探讨。     

毛竹生长发育规律的调查分析

毛竹不同于其它树种,有其独特的生长发育规律。为了掌握毛竹地下部分——竹鞭、笋芽的生长发育规律和竹笋成竹规律,在湖南省湘阴县进行了长期的调查研究,结果发现影响毛竹产量和质量的关键因素是毛竹地下部分的生长发育条件:竹鞭在疏松、肥沃、湿润、板岩或页岩发育的黄红壤中生长最为适宜;竹鞭在土层中分布深、生长壮实,鞭芽饱满、生活力强、萌发力强、发笋多,竹笋粗壮、成竹率高,新竹胸径大、竹竿高、出材率高。     

淡竹林竹笋泉蝇生物学特性与防治研究初报

竹笋泉蝇(Pegomyia Kiangsuensis Fan)属双翅目花蝇科泉蝇属,主要为害竹笋,致使竹笋腐烂、发臭,不能成竹。竹笋因遭此为害,成竹率大为下降。淡竹林一般每年3代笋,2、3代笋受其为害,多不能成竹,竹笋的成竹率仅在50%左右,天长县淡竹林1563.2ha,分布在65000多户,竹林每公顷年收入6145.5元,最多可达15000元以上;据调查,竹笋泉蝇发生面积在     

黄甜竹生长发育规律初步研究

对黄甜竹生长发育规律进行了初步研究,结果表明:黄甜竹发笋期从4月中旬开始至5月上旬止,持续时间约25 d,出笋规律呈偏右正态分布。黄甜竹平均成竹率为61.36%,发笋前期和盛期成竹率相当。幼竹高生长历时45 d,高生长总量可达7～8 m。     

寿竹出笋及竹笋-幼竹高生长规律

通过对寿竹出笋和幼竹高生长阶段的调查,研究了寿竹笋期的生长发育规律。结果表明,寿竹出笋从5月初开始,出笋盛期为5月8日到5月21日,盛期出笋数量占84.7%,出笋全部持续时间约30天。寿竹的高生长持续60天左右,高生长符合Logistic模型。引起寿竹退笋的主要原因是虫害,占退笋的比例74.7%,造成退笋的主要害虫是竹笋泉蝇。该地区寿竹整个出笋期平均成竹率仅为11.7%。     

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.