桉树轻基质扦插育苗技术研究

以椰糠和泥炭土、黄心土作为桉树扦插的轻型基质。通过正交试验设计,研究了3种基质不同配比对桉树无性系扦插繁殖生根数、生根率、生根长度的影响。试验结果表明:以椰糠∶泥炭∶黄心土按2∶4∶2的比例配制成的基质可以在生根率、平均根数、每株根长度等一系列指标中达到较优的水平。但考虑到轻型基质的要求,椰糠:泥炭土,按6∶4的比例配制成的基质为较好的基质比例。     

桉树轻型基质育苗研究初报

桉树作为南方重点发展的工业用材树种,其扦插苗需要量非常大。但目前桉树苗木的生产无法实现工厂化生产,其中一个重要的原因是没有合适的轻型基质。本文研究了以甘蔗渣和树皮等,结合黄心土和珍珠岩作为桉树扦插的轻型基质。实验显示将松树皮∶甘蔗渣∶黄心土∶珍珠岩按5∶2∶4∶4的配方制成的基质可以在生根率,平均根数,每株根长度等一系列指标中达到较优的水平。但考虑到轻型基质的要求,松树皮∶甘蔗渣∶黄心土∶珍珠岩为5∶2∶2∶4为较好的基质,这也是实验中的四号基质,为验证了的较好的配方。     

桉树组培苗轻型基质培育技术研究

通过正交试验设计,以椰糠和泥炭土作为轻型基质进行桉树组培苗移栽育苗试验。结果表明:用加1次0.5%尿素进行堆沤发酵的椰糠与泥炭土按3∶1的比例配成的基质,桉树组培苗移栽效果较好。     

桉树工厂化育苗轻型基质筛选试验研究

应用南方种苗基地附近的农林废弃物为原料配制轻型基质,按照正交试验设计方法,开展了桉树扦插育苗的试验研究,重点研究了以蔗渣、椰糠、稻壳为主要成分的轻型基质对桉树扦插苗根系生根率、生根量、主根长、Ⅱ级侧根发生值、总Ⅰ级侧根长度等的影响,试验结果表明不同基质成分对桉树苗木生长指标影响显著:蔗渣对苗木生根率、稻壳对Ⅱ级侧根发生值、蔗渣灰对总Ⅰ级侧根长度分别起主导作用,椰糠及其与其它基质的交互作用对生根率、生根条数等影响较大,最后筛选出2种可在生产上推广应用的优良轻型基质配方,即:甘蔗渣:椰糠:稻壳:蔗渣灰为1:2:1:0或1:2:0:0.     

桉树扦插繁殖技术

桉树扦插繁殖技术是无性繁殖方式之一，影响桉树扦插生根成苗主要因素是母树的遗传性。采用大荫棚内套小荫棚降温保湿扦插繁植技术、舒根型圆型黑塑料管容器、椰糠＋谷壳＋黄心土轻型混合基质，对提高扦插生根率、成苗率，促进根系生长、苗木生长具有重要作用。     

降香黄檀容器育苗基质试验

采用黄心土、椰糠、泥炭土、塘泥、过磷酸钙和钙镁磷肥6种基质的不同配比,对降香黄檀开展了幼苗培育试验,测定分析了幼苗苗高、地径、单叶面积、生物量和保存率等指标,并计算苗木质量指数,旨在筛选出最适宜的育苗基质,培育优质苗木。结果表明∶不同基质配比处理对苗木生长指标具有明显影响;处理3(V黄心土∶V椰糠=1∶2)幼苗苗高、地径和保存率最好,处理18(黄心土+0.25%钙镁磷肥)幼苗单叶面积、地上生物量和总生物量最好,处理2(V黄心土∶V椰糠=1∶1)幼苗地下生物量最多;按苗木质量综合评比,处理3、处理18、处理2和处理6(V黄心土∶V椰糠=2∶3)均比对照处理1(纯黄心土)好,适合作为降香黄檀苗木的培育基质,而添加椰糠的基质适合作为轻型培育基质。     

白木香不同轻基质配比育苗技术研究

实验选取椰糠、泥炭土和黄心土3种不同轻基质作为白木香育苗基质原材料,采用L9(34)正交试验法,进行白木香不同轻基质配比容器育苗实验研究,分别测定了白木香容器苗地径、苗高、叶绿素和氮素4个生长指标。研究结果表明:不同轻型基质配比对白木香容器苗生长影响不同,表现最优的组合是A6B6C2,即最适宜的轻基质原料配比为椰糠∶泥炭土∶黄心土=6∶6∶2。     

不同基质处理对洋紫荆幼苗生长的影响

文章以黄心土为基础,选用泥炭土、椰糠、蘑菇渣3种常用轻基质材料,设置不同比例组成15种基质配方,通过研究不同基质配比处理下洋紫荆Bauhinia variegata的苗高、地径、地上部分干重、地下部分干重、生物量、根冠比、根系生长,评价其育苗效果,确定培养基最优配比。结果表明:不同配方基质对容器苗的生长有显著影响,处理组Z7(黄心土:泥炭土:椰糠=2:1:1)、处理组Z14(黄心土:椰糠=1:4)、处理组Z5(黄心土:椰糠=4:1)的洋紫荆容器苗综合评价值为0.75,0.63和0.55,Z3(椰糠=1)、Z13(黄心土:泥炭土=1:4)、Z6(黄心土:蘑菇渣=4:1)的洋紫荆容器苗综合评价值为0.32,0.39和0.43。综上所述,黄心土:泥炭土:椰糠=2:1:1的基质配比是洋紫荆容器苗最为理想的轻型基质配方。     

不同基质对巨桉扦插生根的影响

实验选取3种不同扦插基质组合(河沙与黄心土1:1混合基质、珍珠岩与泥炭土1:1混合基质、泥炭土与黄心土1:1混合基质)对巨桉进行扦插试验.结果表明,不同的基质组合对巨桉扦插生根有很大的影响.在泥炭土与黄心土1:1混合基质中,硬枝扦插和嫩枝扦插的效果都是最好的.硬枝扦插的生根率为45％,在另两种基质组合中进行硬枝扦插不能生根;3种基质组合中,泥炭土与黄心土混合基质、河沙与黄心土混合基质、珍珠岩与泥炭土混合基质上嫩枝扦插的生根率分别为43.25％,9％、7.9％.     

紫薇嫩枝扦插基质研究

为研究基质配比对紫薇嫩枝扦插生根质量的影响。采用泥炭、河沙、蛭石、椰糠、珍珠岩配制10种基质进行紫薇嫩枝扦插试验。结果表明,紫薇的生根率、生根数、最大根长及偏根率等生根性状因采用不同的基质配方不同而存在极显著差异。基质配比为泥炭(50%)+珍珠岩(50%)时,紫薇嫩枝扦插的平均生根率最高,为97.64%;基质配比为泥炭(50%)+椰糠(50%)时,紫薇嫩枝扦插的平均生根数最多,为4.04条;基质配比为泥炭(100%)时,紫薇嫩枝扦插的平均最长生根长度最长,为5.95cm;基质配比为蛭石(50%)+椰糠(50%)时,紫薇嫩枝扦插的平均偏根率最低,为16.42%。基质与生根率的关联序为:泥炭珍珠岩蛭石河沙椰糠;与生根条数的关联序为:珍珠岩泥炭椰糠蛭石河沙;与生根长度的关联序为:泥炭珍珠岩椰糠河沙蛭石;与偏根率的关联序为:蛭石河沙珍珠岩椰糠泥炭。紫薇嫩枝扦插选用泥炭、珍珠岩按照合理的比例配制基质,可取得较好的扦插效果。     

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.     

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.     

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.     

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.     

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。     

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.