黄樟切根移袋育苗对比试验

在云南西双版纳州勐海县的中心苗圃开展了黄樟的切根移袋育苗,与苗床常规育苗的对比试验。试验结果表明:通过切根移袋育苗提高了黄樟苗木的质量,苗木高径比差异缩小,促进了其苗高和地径的协调生长。通过切去黄樟苗木部分主根,极显著缩短了黄樟苗木主根的长度(59.675%),促进了苗木侧根的生长,显著提高了苗木的Ⅰ级侧根数(161.905%)和苗木地下部分的鲜重(195.288%),增加了苗木对土壤养分的吸收能力,从而显著地促进苗木的地径生长(22.051%)和地上部分鲜重的增加(42.887%)。其苗高比常规苗床育苗(对照)提高了10.475%、Ⅰ级侧根长比对照降低了12.614%。     

Pt菌剂对高阿丁枫苗木生长的影响

进行高阿丁枫接种Pt菌剂的育苗效果试验。结果表明:Pt菌剂对高阿丁枫苗木的生长有明显的促进作用。经Pt菌剂处理后高阿丁枫苗木的苗高、地径、侧根数、主根长、地上部分鲜重、地下部分鲜重、全重及一级侧根长分别较不经Pt菌剂处理的对照提高了23.1%、8.7%、23.1%、21.0%、25%、33.3%、26.7%、49.2%。且苗木的径高比不失衡。     

Pt、ABT处理对马尖相思苗木生长的影响

通过接种Pt菌剂及施用3号ABT生根粉,进行马尖相思播种育苗试验。结果表明:Pt菌剂和3号ABT生根粉都对马尖相思苗木生长及生物量有明显的促进作用。用Pt菌剂处理后苗高、地径、侧根数、主根长、地上部分质量、地下部分质量、全质量及一级侧根长分别较对照有提高。用3号ABT生根粉处理后苗高、地径、侧根数、主根长、地上部分质量、地下部分质量、全质量及一级侧根长分别较对照有提高。     

西南桦工厂化轻型基质穴盘育苗试验初析

对西南桦的工厂化轻型基质穴盘育苗技术和常规塑料袋育苗技术(对照)进行了对比试验.结果显示,轻型基质穴盘育苗技术比对照提前2～3d达到出苗率最高峰值;苗高、地径、主根长、Ⅰ级侧根数和大于2 cm的Ⅰ级侧根数分别比对照提高12.7％、7.8％、10.5％、37.7％和63.1％.穴盘培育的苗木的苗高、大于2 cm的Ⅰ级侧根数、主根长和Ⅰ级侧根数与对照差异显著,但主根长与苗高、地径、Ⅰ级侧根数间相关性不显著.以上结果表明,工厂化轻型基质穴盘育苗技术能明显提高西南桦苗木质量,在生产中具有较好的推广应用前景.     

景观绿化树种多花含笑育苗基质试验

开展5种配方基质对多花含笑苗木的苗高、地径、主根长、地上部分鲜重和地下部分鲜重生长的影响。结果表明,苗高、地径、主根长、地上部分鲜重和地下部分鲜重生长表现较好的基质配方处理均是处理C,即2/4遮渣+1/4阔叶锯末+1/4牛粪。5种处理的苗高、地径、主根长、地上部分鲜重和地下部分鲜重各处理间均存在极显著差异。试验表明,配比得当的混合基质可弥补单一基质的不足,使容器育苗的优越性更加显著。     

热带珍贵树种羯布罗香苗木质量分级标准

以西双版纳州普文苗圃所培育的1年生羯布罗香容器苗为对象,随机抽样50株样苗,测定地径、苗高、冠幅、主根长、侧根数、全株鲜重、地上部分鲜重、地下部分鲜重、全株干重、地上部份干重、地下部份干重、高径比11个指标并进行相关分析,确定以地径和苗高作为苗木质量分级指标,采用逐步聚类分析方法,结果表明：羯布罗香1年生容器苗木可分为3级,即Ⅰ级苗：D≥0.58 cm,H≥42.38 cm;Ⅱ级苗：0.58 cm>D≥0.47 cm,42.38>H≥25.53 cm;Ⅲ级苗：D<0.47 cm,H<25.53 cm。     

1年生闽楠容器苗苗木质量分级研究

在广西3个闽楠苗木生产地,采用随机抽样法测定1年生闽楠容器苗的苗高、地径、长度5cmⅠ级侧根数等生长指标,并采用主成分分析、K-均值聚类分析方法对苗木质量进行综合评价和分级。结果表明:闽楠1年生容器苗苗木质量主要取决于苗高、地径、单株鲜重、地上鲜重、地下鲜重、单株干重、地上干重、地下干重;根冠比、高径比和长度5cm的Ⅰ级侧根数可为辅助指标。结合生产实践,建立以苗高和地径为质量指标的闽楠苗木分级体系,得到闽楠合格苗木分级标准,即Ⅰ级苗木:苗高31 cm,地径3.0 mm;Ⅱ级苗木:31 cm≥苗高≥20 cm,3.0 mm≥地径≥2.5 mm。     

马尾松无性系种子园自由授粉子代苗期多性状分析

对漳平五一国有林场马尾松无性系种子园自由授粉子代苗期的苗高、地径、主根长、侧根数、生物量 (地上、地下、全苗 )等 7个性状研究表明 :上述 7个性状在家系间均达极显著差异水平 ;各性状相关分析发现 ,苗高、地径、主根长、地上部分生物量、全苗生物量之间存在极显著相关 ,主根长与地下部分生物量、侧根数与苗高之间有显著相关 ,侧根数与地径、侧根数与生物量 (地上、地下、全苗 )无显著相关 ;通过对各性状的等级划分和全苗生物量的LSR检验 ,初步筛选出 4个优良家系 ,有良好应用前景。     

杉木优良家系苗期性状的遗传变异和相关研究

对杉木１２０个优良家系子代苗期的苗高、分枝数、根系发育、生物量等１５个主要性状进行了遗传变异研究。结果表明：家系间在苗高、分枝数、侧枝盘数、侧根数,侧根长、冻害率、地下鲜重、地下干重、全株干重等性状上的差异达显著水平以上。侧根数、侧根长、主根长、全株鲜重、地上鲜重、地下干重等性状差异不显著。苗高、侧根长、冻害率、地下鲜重、侧根数、地下干重等性状有较高单株遗传率,受较强的加性遗传效应所控制,其他性状受环境影响较大,苗木冻害率与纬度间中度负向相关,来自南部家系易受冻害,北部家系有较高抗寒性,其他性状的地理变异趋势不明显。因此遗传改良作苗期选择时,除了注意苗高和地径生长外,应把苗木侧根的发育情况视为选择的指标之一。在良种推广应用上,须考虑到家系抗寒力的适应地域。     

2种规格育苗容器袋对油用香樟幼苗生长的影响

以苗木成活率、苗高、地径、苗木鲜重/干重、地上部分鲜重/干重、地下部分鲜重/干重为评价指标,在广西国有钦廉林场林科所科研苗圃内开展7 cm×10 cm和5 cm×7 cm 2种规格育苗容器袋试验,结果表明:2种规格育苗容器袋培育油用香樟对苗木成活率影响不大,对苗高、地径、苗木鲜重、地上部分鲜重/干重、地下部分鲜重差异极显著,对苗木干重、根系长差异显著,对苗木地下部分干重、根系数差异不显著。综合各指标可知:2种育苗容器对油用香樟苗木质量指数差异极显著,使用7 cm×10 cm培育油用香樟的苗木质量指数大于使用5 cm×7 cm培育油用香樟的苗木质量指数。为此,建议实际生产上采用A容器袋培育油用香樟苗木。     

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.     

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.     

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.     

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.     

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。