四翅滨藜生物学特性及荒山引种造林成活率试验

通过引进四翅滨藜进行荒山引种造林试验,观察总结出四翅滨藜的生物学特性,同时针对不同立地条件下的造林成活率进行了调查分析,在石灰岩山地造林和在玄武岩山地造林成活率均达90％以上,二者成活率无明显差异。     

四翅滨藜造林试验

从青海引种四翅滨藜进行造林试验。通过4年的试验观测,取得以下结论：①宁夏南部山区特别年降水量300 mm以上的地方是四翅滨藜生长适宜的生态区域,而中北部年降水量200 mm以下的干旱区,发展四翅滨藜需要有补水条件;②容器苗造林是提高成活率的有效措施;③与豆科植物混交造林效果好。     

四翅滨藜容器育苗及造林技术研究初报

四翅滨藜是由美国引进的优良准常绿饲料灌木树种。文中就四翅滨藜容器育苗技术，以及一年多次育苗多次出圃造林技术等开展了研究分析，研究结果可为该树种的大面积推广提供技术依据。     

吉林西部四翅滨藜苗木培育及造林技术

四翅滨藜属蓼科滨藜属的常绿或半常绿灌木,具有抗干旱、耐瘠薄、耐盐碱的特性,与其他灌木相比,它的枝叶含有丰富的营养物质,为牛羊的好饲料。经过引种试验,适合在吉林省西部栽培,文章主要介绍了四翅滨藜的苗木繁育及造林技术。     

四翅滨藜在乌兰察布市引种繁育试验

四翅滨藜是美国农林部门经过25年努力选育出的优良品种，现已被广泛用于牧场改良、水土保持、造林等，有“奇迹树”之称。乌兰察布市地处干旱、半干旱地区，风蚀沙化严重，水土流失，牧场退化，生态环境十分恶劣，常遭沙尘暴危害。四翅滨藜是沙源治理、防治土地沙漠化、防风固沙方面的首选优良树种之一，推广四翅滨藜对乌兰察布市畜牧业建设及生态建设具有重要意义。     

山西北部四翅滨藜生态饲料林及几点建议

通过对四翅滨藜营养价值、适口性、生物量等调查研究,认为四翅滨藜是一种优良生态饲料林灌木树种。针对山西省北部自然条件及四翅滨藜引种现状,对其发展四翅滨藜生态饲料林提出了建议。     

四翅滨藜在固阳县的引种试验研究

包头固阳地区自然气候条件恶劣,可供造林的树种贫乏,四翅滨藜耐干旱、瘠薄、耐盐碱,适应性强,既是林又是草,是林草兼用的饲料植物,对牲畜有较好的适口性。四翅滨藜可采用播种子和扦插繁育,但用半木质化的嫩枝扦插繁殖成苗率高,生产成本低,技术简单。是包头固阳地区造林、盐碱地改造、荒山营建灌木林的较理想的树种之一。     

滨藜属植物的生长发育规律研究

对努塌滨藜、三角滨藜和四翅滨藜三种滨藜属植物进行了物候期观察、并对其各器官的生物量以及光合速率,蒸腾速率等指标进行观测。其中,对四翅滨藜苗期的生长发育状况进行了重点观测,并和其他两种滨藜属植物及沙棘苗期的生长发育状况进行对比,结果表明,四翅滨藜幼苗较沙棘生长更快,植株更健壮,适合大面积推广。     

四翅滨藜容器苗合理出圃高度的研究

通过对容器苗根系生长同地上部分生长关系以及不同高度容器苗造林成活情况的调查研究, 确定四翅滨藜最佳出圃高度为6 ～20cm , 使该树种1 年可连续育苗、出圃造林3 次。     

生态治理新树种——四翅滨藜

滨藜是干旱半干旱地区的典型植物。四翅滨藜是美国科罗拉多洲立大学经过25年的努力,选育出的一个改良品种,被广泛用于牧场改良、水土保持和盐碱地改造等。从1990年开始,我国青海、新疆、宁夏等地进行了四翅滨藜区域性栽培试验,表现出了极强的生命力,具有很大的发展潜力。1.四翅滨藜的生物学特性和形态特征四翅滨藜为旱生或中生植物,喜光,不耐遮阳,不耐潮湿。根系发达,一年生露地苗根深可达3.4m,二年生根深4.6m,是植株高度的5倍左右。四翅滨藜属于自由授粉植物,其子代分化十分明显,形成各种不同的形态类型。四翅滨藜为准常绿灌木,高1～2m,枝…     

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.