枫香不同家系生长差异研究

对5年生的枫香(Liquidambar formosana)不同家系的人工林进行了生长差异分析,结果表明:选出与CK对照组之间胸径、树高与单株材积各指标差异极显著的家系8个,分布为家系6号、29号、34号、50号、57号、60号、104号、106号;2008~2010年间枫香8个家系之间的胸径生长量、树高生长量与材积生长量均值均存在极显著差,其中家系50号和60号生长表现最为活跃;5年生枫香8个家系人工林之间的胸径均值、树高均值与单株材积均值均存在极显著差异,其中与CK组相比较相对最优良的是家系6号和60号,CK组的胸径均值为6.54cm,树高均值为5.31m,单株材积均值为0.01054m3,家系6号的胸径、树高与单株材积均值分别比CK组大46.87%、47.99%与83.96%,而家系60号则分别大43.33%、46.26%与81.30%。     

29个青海云杉家系苗期生长性状遗传变异及选择研究

对29个青海云杉(Picea crassifolia Kom.)家系苗期6年生生长性状进行遗传变异分析,研究结果表明:苗高和地径均表现出极显著差异,具有丰富的遗传变异基础。苗高的家系遗传变异系数为16.6%,地径家系遗传变异系数为11.8%。综合评价苗高地径生长性状后,选择了4个优良家系:8-101,8-104,8-72和8-14。这4个优良家系的苗高遗传增益达17.4%,地径遗传增益达8.4%。苗高生长量最大的家系为8-72,比苗高生长量最小的家系8-36高90.0%,比全部家系苗高平均值高26.5%。各家系苗高与地径、新梢生长呈正相关,相关系数分别为0.840 2和0.9242,各性状差异极显著。     

36个落叶松家系苗生长变异规律研究

对甘肃省小陇山林业实验局林业科学研究所36个家系落叶松苗期（2年生）进行变异分析各家系间存在变异，变异系数在3．0％～29．0％，平均为13．6％。各家系间苗高生长量差异极显著，191号家系苗高生长量最快，为51．5cm，64号家系苗高生长量最慢，为35．2cm，生长最快的191号苗高比生长最慢的苗高快64．3％；通过家系间的选择方法，能够实现落叶松生长的遗传优良选育。     

光皮桦优良遗传材料选择及改良前期效果

从形质指标、绝对生长量指标、相对生长量指标、木材材性指标4个方面制定了光皮桦选优标准,并确选优树28株。优树树高、胸径、木材密度、纤维含量、纤维长度分别大于林分平均值4．3％～45．9％、29．0％～81．7％、1．3％～10．3％、1．2％～10．1％、0．7％～9．6％。30个材料子代测定表明：优树子代不同的家系间,树高、胸径生长差异均达到极显著水平。经LSD显著性分析,评选出麻17、麻11、杨5、麻27、杨1、麻3、麻20、麻15共8个优良家系,可在生产中推广。     

水曲柳种子园半同胞子代遗传测定及优良家系选择

水曲柳种子园10年生半同胞子代家系树高、胸径和材积之间差异极显著;在参试的15个家系中树高有13个超过对照,生长量最大的是对照的1.15倍。胸径均超过对照,生长量最大的家系是对照的1.41倍。材积均超过对照,生长量最大的家系是对照的2.40倍;树高、胸径、材积家系遗传力分别是0.11、0.40、0.20,以材积显著大于对照为主要依据,参考树高、胸径两性状的表现,综合评选出7、4、9号3个优良家系,分别比对照,树高提高12.4%~14.8%,胸径提高32.7%~41.1%,材积提高120%~140%。7号家系各项指标均排在第一位,为最优家系;从15个家系中选出1个、2个、3个优良家系,其实生后代10年生时,树高能获得0.7%~0.9%的遗传增益,胸径能获得5%~7%的遗传增益,材积能获得6%~8%的遗传增益。     

不同种源的马尾松半同胞家系子代苗期生长表现

对来自湖南、广西、浙江、广东、福建等5个省的36个马尾松半同胞优良家系自由授粉子代苗期生长表现进行分析。结果表明:不同种源马尾松家系苗的平均地径和苗高生长差异均达到了极显著水平,平均苗木高生长、地径生长均以湖南、广东、广西3个种源的较好。不同家系之间在苗高、地径生长上也表现出极显著的差异,高生长以GXGLN2号家系为最好,其次是HN29号、GD1号家系;地径生长以GD8号家系为最好,其次是HN7号、GXGLN2号家系。综合考虑高生长和地径生长,GXGLN2号家系表现最好。马尾松苗高与地径生长存在着极显著的正相关。     

长白落叶松变异分析及优良家系早期选择

以黑龙江省鹤岗市林木良种繁育中心的84个长白落叶松自由授粉家系子代林为研究对象,测定其树高,结合变异分析、方差分析、多重比较及年生长量分析等,对长白落叶松家系进行早期选择。结果表明:长白落叶松树高性状存在丰富的变异,变异系数幅度为26.81%～35.66%。来源于渤海、错海、鹤岗及林口4个种子园家系的平均变异依次为30.50%、30.47%、28.97%、30.12%,依次比对照大8.62%、8.51%、3.17%、7.26%。4年生、5年生、6年生时树高在家系水平上差异均达到极显著水平,树高遗传力平均为90.7%,20%入选率时,遗传增益平均为38.74%。结合多重比较及树高生长量分析结果,最终选择出生长良好、生长快且稳定的家系为BS54、BS542、CH4、HG28及LK299,且6年生时,平均树高为1.34m,平均变异系数为31.62%,平均年生长量为0.43m,平均现实增益为36.66%。     

半年生思茅松半同胞家系生长量调查研究

为了选择思茅松优良家系,对半年生9个家系和1个对照的造林苗木进行树高、地径观测。结果表明,所有家系的树高生长量和地径生长量均大于对照。方差分析结果表明,家系间树高生长量和地径生长量均存在极显著差异。树高生长量与对照相比,有7个家系差异达到极显著水平;地径生长量与对照相比,有8个家系差异达到极显著水平。     

红锥半同胞子代家系幼林生长变异研究

对3个地点的33个红锥(Castanopsis hystrix)半同胞子代家系10月龄幼林的生长性状(树高、地径、冠幅等)进行测定,以了解不同红锥半同胞子代家系幼林生长变异性。结果表明,家系之间树高、地径、冠幅等生长性状均存在显著差异,各家系之间存在遗传变异,具有良种选择的遗传基础。红锥P3、A11、R3、A8、A5、A2、P6、B5、B2、R4、D1等家系在南宁表现较好,P8、P7、P3、R6、A7、R3、P6、D1、B5、A5、D3、B2、R5等家系在玉林具有较大生长潜力,P1、P7、P3、D3、B5、B2、R4、A2、P6等家系在柳州具有较大生长潜力。综合比较各家系在3个地区的生长表现,初步筛选出在各地均表现优良的P3、P6、B5、B2四个家系,分别归属于凭祥和博白种源,其树高生长量分别为1.37 m、1.23 m、1.23 m、1.19 m,比较对应一代家系分别增长7.62%、14.97%、20.29%、3.21%,遗传增益分别为6.52%、12.82%、17.37%、2.75%。在同一地区种植的红锥家系生长性状与环境相关性均不显著。     

不同种源及家系山桂花3年生人工幼林林木的高、径生长效应

对所营建的4个地理种源及其99个家系山桂花人工幼林(3年生)林木树高和胸径生长量的测定与分析结果表明:其山桂花人工幼林在种源及其家系间林木的树高和胸径生长差异显著,其中以普文种源生长为最好,3年生山桂花人工林林木的树高达2.3 m,胸径为1.8 cm。而3年生山桂花人工林林木的树高生长以19号家系表现最优,林木胸径生长以28号家系表现最优。综合表现最佳的家系有1、2、3、4、7、8、10、11、12、15、18、19、20、21、23、24、25、26、27、28、29、30、31、36、46、47、71,共27个。     

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.     

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.     

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。