三个白杨无性系扦插苗年生长规律及抗病性比较

在陕西吴起县引种研究了秦白杨5号、新疆杨3号、河北杨5号等3个杨树无性系扦插苗高年生长动态并比较抗病性,结果表明:3个杨树无性系扦插苗高生长规律与"S"型生长曲线一致,年生长规律可用Logistic方程表达,相关系数值0.98以上。扦插苗年生长分为:苗木生长前期、苗木速生期和苗木生长后期,并且3个时期在时间长短以及高生长量上有很大差别。秦白杨无性系苗的速生期时间为40d,日平均生长量达1.374cm,累积生长量达到54.97cm,占到整个生长的57.50%,不到1/4的时间内完成全年一半以上的生长量。3个杨树无性系对黑斑病和叶枯病的抗性表现出差异,秦白杨的黑斑病发病率小于新疆杨和河北杨,感病指数介于新疆杨和河北杨之间;秦白杨叶枯病感病指数最低,秦白杨对黑斑病和叶枯病有很好的抗性。3个杨树无性系叶部病害抗性综合评价结果为:河北杨秦白杨新疆杨。秦白杨高生长和抗病性都表现优良,适宜在吴起县栽植。     

几个杨树品种1年生苗高度年生长规律的研究

用Logistic方程对欧美杨107号等5个主要杨树品种1年生插条苗的年高生长规律进行了模拟研究.结果表明:Logistic方程能很好地表达5个杨树品种的苗高年生长动态,相关系数均达0.98以上;苗高生长期可划分为3个阶段,生长前期、速生期和生长后期,日生长量最大时间出现在第120 d左右,速生期出现在第93 d和142 d之间,持续50 d左右,占整个生长期的约24％,但生长量却约占年总生长量58％.     

西丰杨无性系苗期生长规律研究

以10个西丰杨无性系进行引种试验,结果表明无性系之间苗高的差异显著,选择出高生长量超出对照20%的无性系——西丰6,并利用Logistic方程对西丰6的苗高年生长节律进行拟合,建立了数学模型,相关系数在0.95以上。速生期内的生长量占总生长量的比率较大,为57.74%,说明速生期的生长量决定着整个生长期的生长量,因此应重视速生期的苗期管理。     

鲁林9号、鲁林16号杨树新品种生长节律研究

为研究鲁林9号、鲁林16号杨树新品种的生长特性,为育苗和造林提供理论指导,以鲁林9号、鲁林16号及对照I-108杨1年生扦插苗为研究对象,利用Logistic方程对3个杨树无性系的苗高、胸径的生长节律进行拟合并对叶片的生长特性进行了研究。结果表明:利用Logistic方程拟合效果显著,相关系数皆在0.99以上,并以此将各无性系的年生长过程划分为成活期、生长前期、速生期和生长后期4个时期。鲁林9号杨和鲁林16号杨速生期持续时间长于I-108杨,速生期内的苗高生长量占总生长量的比率达到63%,地径生长量占总生长量的比率最达66%,地径进入速生期的时间早于苗高。鲁林9号杨和鲁林16号杨单叶生物量的累积量大,相对含水量高,对光能的利用能力强。对2个杨树新品种年生长规律及生长特性的研究,为加强林木生产管理提供了理论依据。     

伊犁地区引种9个杨树无性系1年生扦插苗生长节律研究

为开展杨树无性系苗期试验研究,对引种杨树无性系进行了苗期初步筛选,为进一步做好良种选育工作奠定基础。试验采用随机区组,对1年生无性系苗木进行了苗高和地径的生长节律研究,并对1年生无性系苗木年生长量进行了方差分析。试验结果表明:各无性系苗高和地径生长曲线形状和趋势基本一直,均成"S"生长曲线,但各无性系之间存在一定的差异;渤丰1号的地径速生期最长,LX-2的苗高速生期最长,拟小青的苗高和地径速生期最短;LX-2、渤丰1号和014苗高生长量较对照增幅77.42%、58.20%、52.64%;178-2-145、108和LX-2的地径生长量较对照增幅51.16%、49.61%、44.96%。供试的无性系LX-2、渤丰1号、014、108、178-2-145和中绥12号,1年生苗木年生长量均优本地良种加小×俄9号。     

无患子苗期生长参数分析

定量分析了无患子苗期地径、苗高生长规律,并利用Logistic模型对其地径和苗高年生长节律进行拟合。结果表明:无患子1年生播种苗地径和苗高年生长节律可划分为始盛期、速生期、盛末期3个阶段。在始盛期,苗高、地径生长量分别占全年总生长量的21.56%和18.96%;进入速生期后,苗高、地径生长量占全年生长量比例为58.83%、66.90%;进入盛末期,苗高、地径生长量占生全年生长量比例仅19.61%,14.14%。苗木地径、苗高生长量与生长时间均存在着极显著的相关关系,拟合的数学模型可靠性高,可用于指导实际生产。     

不同漆树品种1年生种子苗生长趋势分析

为漆树[Toxicodendron vernicifluum(Stokes)F.A.Barkl.]优良品种育苗管理提供参考,对"天水大叶木漆""大红袍""贵州红漆"等3个品种1年生苗地径、苗高年生长趋势进行了分析和曲线拟合;结果是3个漆树品种地径、苗高年生长趋势一致,符合Logstic生长曲线,生长期约为130d,划分为前慢期、速生期和后慢期3个阶段,地径、苗高速生期约60d,速生期"天水大叶木漆""大红袍""贵州红漆"地径生长量分别占全年生长量的63.28%、62.00%和65.82%,苗高生长量占全年生长量的75.99%、77.61%和71.30%;3个漆树品种地径、苗高拟合方程的相关系数分别≥0.961和≥0.951,呈极显著正相关,拟合效果理想,能很好地对漆树种子苗年生长动态进行实时监测和预测。     

油茶优良无性系1年生苗木生长表现

为给油茶良种优质苗木的培育与合理施肥提供理论依据,定量研究了赣无系列油茶24个无性系的生长规律,将其苗木生长过程划分为前慢期、速生期和后慢期3个阶段,从9月中旬开始各无性系的苗高与叶片都进入速生期,9月下旬达生长高峰,各无性系间生长量差异不显著,但不同生长阶段差异显著;同时,调查分析了各无性系苗木成活率与保存率变化情况,其中赣无24、赣447、兴46与赣190成活率较高,无24与赣84-3成活率较低;各无性系保存率随时间递减,其中赣84-8、赣83-1、赣447与赣无24最终保存率较高,而无12保存率最低.不到60%.     

L35等黑杨新无性系苗期生长规律研究

以4个黑杨派(Populus Aigeiros)无性系为材料,利用Logistic方程对1年生扦插苗木的苗高、地径的年生长节律进行拟合.结果表明:利用Logistic方程拟合效果显著,相关系数皆在0.97以上.并以此将无性系扦插苗的生长过程分为成活期、生长前期、速生期和生长后期4个时期,其中速生期内的苗高生长量占总生长量的比率平均为59.4%,地径生长量占总生长量的比率平均为63.0%.     

5个香椿无性系嫁接苗苗期生长节律分析

调查5个香椿无性系嫁接苗嫁接后8个月苗高和基径的生长状况,可知苗高和基径的年生长趋势均为典型的"S"型曲线,即呈现出"慢-快-慢"的生长规律,苗高和基径的生长主要集中在8月份以前,8月份以后苗高和基径的生长变化不明显。在11月份落叶时,5个香椿无性系嫁接苗的苗高可以达到35.3cm-95.1cm,基径可以达到1.03cm1.59cm。利用Logistic曲线方程对5个香椿无性系嫁接苗苗高和基径的生长节律进行拟合,建立了不同无性系嫁接苗苗高和基径苗期的生长曲线拟合模型,拟合相关系数均在0.98以上,达到了极显著水平。通过对拟合的Logistic曲线方程进行二次求导得出的速生期进行分析,香椿嫁接后基径比苗高更早进入速生期,基径最早嫁接后一个月左右就可进入速生期,而苗高最早则需要45d左右。香椿基径的速生期也比苗高长,可维持在大概75d~90d,占到了总生长期的1/3左右,而苗高的速生期仅有45d~60d,苗高和地径的速生期生长量均超过了总生长量的一半以上。而不同无性系不但进入速生期的时间点有着明显的差异,且其速生期的长短也有着明显的差异,其中,本地无性系最早进入速生期,且其速生期也最长。     

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.     

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.