假色槭驯化苗木物候特征观察

对假色槭驯化苗进行生物学物候观测发现:(1)假色槭驯化苗木随着龄级的增长,树皮由光滑趋于粗糙,颜色由绿转红最后趋于深灰,皮孔从有趋于消失.(2)假色槭观赏期约20天左右,最佳观赏时间在9月下旬至10月初.(3)假色槭驯化苗的树形分化明显,灌木状株型占明显优势.(4)灌木状植株的萌生条生长迅速,当年生长量达80cm以上;有明显主干植株的生长量小,仅在30cm左右.     

山西假色槭驯化苗物候与生长特征观测分析

在山西省进行假色槭的引种栽植和驯化试验,对假色槭苗的生长特性和物候特征进行了观察、记录和分析研究。结果表明:在假色槭的整个生长期,只要有新叶萌生,假色槭植株就会有彩色叶呈现,彩色叶伴随整个生长期;假色槭越冬后有干冻梢现象发生,这与引种栽植地的气候状况及假色槭的木质化程度有关,同时也可能与其遗传性状有关;引种苗第1年基本处于缓苗期,生长较慢,适应了环境后,随着引种苗树龄的增加,植株的生长量也在不断增加。     

葛萝槭生物学特性及园林应用初步研究

葛萝槭具有独特的观赏特性,对葛萝槭进行开发利用,对城市园林建设具有重要的意义。笔者对葛萝槭物候期和生长情况进行了观测,对植株栽培成乔木型、丛生型、球型进行了试验。结果表明：葛萝槭全年高生长有2次高峰,分别出现在6月和8月,年均苗高净生长量为79.4 cm,年均地径净生长量为1.27 cm;葛萝槭适合培养成独杆乔木型、丛生型、球型,球型冠径不宜小于1.2 m。同时对其在园林造景中的应用进行了探讨。     

假色槭丛状绿化苗培育技术

假色槭树冠伸展,枝条疏密性较好,是枫树观赏树种的极品。由于抗逆性很强,在北方街道绿化保存率和完好率较高,深受市场青睐。文章从生产实践中总结出假色槭实生苗繁育技术及丛状绿化苗培育技术,突出了繁育优质壮苗和丛状绿化大苗的实用繁殖技术,可供从事育苗和生产部门借鉴。     

假色槭播种育苗技术要点

指出了假色槭的形态特征、生活习性、主要分布及其用途,在安图县明月苗圃和辉南森林经营局四岔苗圃开展了假色槭的育苗试验研究,通过生产实践,总结了假色槭苗木培育的成功经验,并详细地探讨了假色槭苗木的培育技术要点及其管理措施。     

观赏槭树的苗期试验初报

观赏槭树育苗试验表明,不同树种、种源间种实发芽率差异较大。发芽率较高的种类有樟叶槭(92%)、鸡爪槭(90%)、三角枫(90%),其次是复叶槭(85%)、红花槭(82%)、橄榄槭(76%)和元宝槭(75%);茶条槭、五角槭、罗浮槭发芽率均小于70%。1年生苗高生长量以复叶槭最大(113.98 cm),其次是三角枫(101.21 cm);樟叶槭和鸡爪槭1年生苗生长量中等,当年生长量分别为62.43 cm和71.74 cm;罗浮槭、青榨槭和橄榄槭1年生苗高生长量较小。季节生长节律有3种类型:橄榄槭、鸡爪槭、元宝槭、茶条槭等几种槭树表现为第1类型(前期生长型),即5月前苗木缓慢生长,6~7月进入速生期,7月以后苗木渐渐停止生长,速生期较短。复叶槭和青榨槭表现为第2种类型:1年生苗全年高生长有2次高峰,出现在6月和9月;樟叶槭和三角枫季节生长节律表现为第3种类型:5月生长缓慢,6月生长开始加快进入速生期,一直持续到8月底,速生期长。三角枫、橄榄槭、鸡爪槭、元宝槭、茶条槭、复叶槭和青榨槭等几种槭树表现出较强的抗寒性,樟叶槭和罗浮槭抗寒性较差。     

假色槭播种育苗技术要点

指出了假色槭的形态特征、生活习性、主要分布及其用途,在安图县明月苗圃和辉南森林经营局四岔苗圃开展了假色槭的育苗试验研究,通过生产实践,总结了假色槭苗木培育的成功经验,并详细地探讨了假色槭苗木的培育技术要点及其管理措施。     

GGR7号在假色槭播种育苗中的应用

在假色槭播种育苗中,通过使用GGR7号绿色植物生长调节剂,研究GGR7对假色槭生长量、侧根数量及侧根平均长度的影响,并对不同处理下苗木的长势、色泽、叶片大小、枝条旺盛等情况进行观察,结果表明:使用含量为100mg·kg-1的GGR7号浸种24h,育苗效果最好,苗木生长快,出苗率高,出苗整齐,生长旺盛,根系发达,栽植成活率高,总体上能提高庭院绿化效率。     

假色槭 青楷槭 花楷槭萌生规律及经营措施的探讨

在森林采伐抚育过程中,由于对假色槭、青楷械、花楷槭等非目的树种的大量采伐和清理,致使这些树种大量萌芽丛生,严重影响林地幼苗幼树的生长,不利于森林更新。为合理经营假色槭等非目的树种,提高森林采伐、抚育更新效果,对假色槭、青楷槭、花楷槭(以下简称“三槭”)萌生规律及经营措施研究探讨如下。     

彩色树种引种栽培试验

通过对试验的20个彩色树(品)种进行驯化栽培,结果表明:可以在长白山区应用的有17个,其中:外来彩色树(品)种10个,分别是中华金叶榆、金山绣线菊、金焰绣线菊、俄罗斯红叶李、王族海棠、钻石海棠、紫叶风箱果、金叶风箱果、紫叶稠李、金叶复叶槭;乡土野生彩色树种7个,分别是假色槭、茶条槭、白牛槭、拧筋槭、花楸、长白忍冬、接骨木。暂时不宜应用的有3个,分别是金叶红瑞木、金叶莸和金叶连翘。     

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.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

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。     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.