云南松单板类人造板材良种选育的研究

以云南松优良群体为选择基础，以优株为选择对象，在评出的优良产地内选择了石屏牛达，龙朋，双柏鄂嘉，雨龙，云龙天池，大栗树，禄丰樟木箐等天然优良林分，在林分内按优树标准开展了优良个体选择，共选择表型较好的优株205株，分株开展了多点年度间的表型测定，以3－4年生优树子代的生长量及优树的纹理通直度，木材密度，松脂含量作为选择性状，经对各性状的遗传力和权重值等进行综合选择，评选了牛达39号，13号，28号，18号，3号，龙朋6号，5号，2号，双柏鄂嘉3号，17号，双柏雨龙12号，腾冲古永9号，贡山8号，云龙1号等32个符合单板类人造板材良种要求的优良单株，它们的树高增长率79．0％－13．3％，实际增益30．63％，遗传增益16．85％，其中有21个家系的木材密度提高了5．59％，松脂含量为对照的82．4％，树干通直度达97．6％，评选出的这些优株已进行了保存和利用。     

云南松优良家系、单株主要性状的遗传分析及综合选择

对昆明、永平 2个云南松种源试验林和石屏、建水 3个 3～ 4年生云南松自由授粉子代试验林进行遗传分析及综合选择 ,结果表明 :云南松高、径生长 ,木纹理通直度 ,木材密度和松脂含量在家系间、单株间差异显著 ,其中树高遗传力估值为 :0 2 8～ 0 5 75 ,地径遗传力估值为 :0 16～ 0 6 6 6 ,材积遗传力估值为 :0 5 2～0 6 7,木纹理通直度的遗传性被高度控制 ,估值达 0 85 ;木材密度次之 ,估值为 :0 5 2～ 0 83;松脂含量的遗传力估值为 :0 4 5 3～ 0 73。借助于约束或非约束选择条件能有效地进行生长、形质和材性兼优家系、单株的选择 ,综合评选出牛达 39号、龙朋 5号、双柏鄂嘉 17号等 32个优良家系。入选的优良家系高生长实际增益30 6 3% ,遗传增益 16 85 % ,说明依据主要性状联合评选出的家系其优良性能是极其显著的。试验还在 2个种源试验林内共同选出广西乐业、贵州兴义、云南双柏、云龙、富宁、开远 6个优良种源、 2 7个优良单株 ,为进一步开展优良家系、单株的选择 ,提供了物质基础。这批家系和单株适宜在单试点、双试点或多试点上推广应用。     

云南松优良家系、单株主要性状的、遗传分析及综合选择

对昆明、永平2个云南松种源试验林和石屏、建水3个3—4年生云南松自由授粉子代试验林进行遗传分析及综合选择，结果表明：云南松高、径生长，木纹理通直度，木材密度和松脂含量在家系间、单株间差异显著，其中树高遗传力估值为：0．28-0．575，地径遗传力估值为：0．16-0．666，材积遗传力估值为：0．52-0．67，木纹理通直度的遗传性被高度控制，估值达0．85；木材密度次之，估值为：0．52—0．83；松脂含量的遗传力估值为：0．453-0．73。借助于约束或非约束选择条件能有效地进行生长、形质和材性兼优家系、单株的选择。综合评选出牛达39号、龙朋5号、双柏鄂嘉17号等32个优良家系。入选的优良家系高生长实际增益30．63％，遗传增益16．85％，说明依据主要性状联合评选出的家系其优良性能是极其显著的。试验还在2个种源试验林内共同选出广西乐业、贵州兴义、云南双柏、云龙、富宁、开远6个优良种源、27个优良单株。为进一步开展优良家系、单株的选择，提供了物质基础。这批家系和单株适宜在单试点、双试点或多试点上推广应用。     

主成分分析法在四川桤木优树选择中的应用

建立用主成分分析法选择四川桤木优良单株的方法,确定其优树选择标准,为四川桤木早期实生选择、良种选育提供理论依据。以初选的157株优树为研究对象,检测其生长和材性性状,并对其进行变异分析、主成分分析。结果显示,树干圆满度(SF)和树干通直度(ST)在林分间差异不显著,其余性状在林分间差异均达到极显著水平。SF、ST和木材气干密度变异较小,其余性状均存在丰富的变异。四川桤木丰富的变异为优树选择提供了前提,经主成分分析,把树高(H)、胸径(DBH)和材积(V)这3个性状作为其选优的标准,选出8株生长表现优良的单株,即GZLD-5、GZLD-6、MYPW-8、GZTJ-1、GZLD-8、MYPW-7、MYPW-10和GZLD-12。本研究结果与植株的实际表型相符合,表明采用的方法具有一定的科学性和可行性。     

油茶优株当代鉴定工作小结

油茶优株当代鉴定又称无性系鉴定。用嫁接或扦插的方法,测定优株的表型性状,有没有相应的遗传根据。 我们按表型性状选出的优树,优良的表型性状,受不受遗传性的制约,或是不是遗传性的反映;如用这些优树繁殖造林,是否象优树入选时那样丰产?这就需将各地中选的表型优树,集中到一个或几个适于油茶生长,而环境条件基本一致的地段作造林比较鉴别,以消除环境条件和人为的影响。从中判别各优树间基因型差异,选用基因型有质的差异的优树建立采穗圃,繁殖苗木供造林用,可获得较大的遗传增益。     

湿地松、加勒比松人工林优树选择研究

以树高、胸径、材积为生长量指标,结合干形、冠幅、皮厚等形质指标,采用5株优势木对比法对40 a生湿地松(Pinus elliottii)、13~40 a生加勒比松(P. caribaea) 人工林开展优树选择研究,提出优树选择标准。40 a生湿地松优树树高、胸径、单株材积分别大于5株优势木平均值的1%、15%、35%以上,树干通直,共选择出优树10株,入选率为 4348%。13～40 a生加勒比松优树树高、胸径、单株材积分别比5株优势木平均值大8%～12%、15%～22%、49%～70%,树干通直,共选择出优树77株,入选率为 4919%。湿地松、加勒比松优树选择应以生长性状为主要目标,同时注重木材密度、产脂等性状的选择,进而丰富其育种群体的遗传多样性。     

木荷优树生长与叶果性状分析

从木荷(Schima superba)优树树龄结构、选优林分起源和表型性状进行分析.结果表明,由于人为破坏,木荷大龄资源较少,仅有40%的优树处于最佳采种年龄;选优林分起源相对合理,天然林选出的优树株数占比达52.1%,次生林和人工林选出的优树株数分别占24.9%、22.9%;树高、胸径生长性状分析认为五株优势木法选出的木荷优树是合理、有效的,通过比较,在现有资源中选出最优的种质材料,作为遗传改良的基础材料,本批优树胸径与5株优势木平均胸径差异幅度大于20%以上的优树有146株,占比达69.52%;优树胸径年均生长量达速生指标的有173株,占86.43%,而树高生长量达速生指标的优树有175株,占68.05%;从形质性状分析结果显示,优良树干尖削度,即高径比在50以上的优树有114株,占比达61.63%;在冠幅方面,优良冠幅的优树,即冠幅小于等于6 m的有128株,占总株数的53.56%.木荷优树的叶果性状在个体及种源间均呈极显著差异(P<0.01),聚类分析显示木荷优树叶果有4种类型.在以后深入研究中,应对生长量大、尖削度小且为窄冠型优树的研究与利用加以重视.     

二十个油桐优良单株后代测定

从正安39株油桐优树中选择20株进行子代及无性系测定,6年的观察研究表明,2号、5号家系为优良家系,家系遗传增益达12.9％;5号无性系为优良无性系,遗传增益达27.7％。5号优树在群体子代和无性系测定中均表现出了良好的遗传品质和较高的遗传增益,应加速利用。     

木麻黄优树选择遗传效应的研究

分别于1976、1986年,在福建省木麻黄主要栽培区的七个县市,进行优良单株选择工作,共选优树178株。采集自由授粉种子,开展子代测定,经过三年重复,二个地点的测试表明,木麻黄半同胞子代间差异达显著水准,优树后代遗传潜势较大,4年生时,约2/3的家系优于对照,表型选择是有效的,初步评选出16个优良家(系),其树高平均遗传增益为20.8?%,胸径遗传增益为18.29%,材积遗传增益为54.74%,选择效果十分明显。其中龙4、莆20、平18等家系在不同年度重复和地点重复均表现突出,可作为广谱优良家系在福建沿海地区推广,文中就遗传方差份量及生长趋势也进行了探讨。     

太谷壶瓶枣优树选择研究

在太谷县小白乡、明星镇、侯城乡等9个壶瓶枣地理标志产品保护地开展优树选择研究,结果表明,复选出的12株壶瓶枣优树在产地具有典型代表性。在丰产指标上,12株优树的冠幅产量达0.28 kg/m2,平均株产47.63 kg,表现出优良的丰产性状,其中,2号和11号的冠幅产量较高,均在0.5 kg/m2以上;在果实经济性状上,12株优树枣果的平均糖含量为28.11%,平均VC含量为462.86 mg/100 g,平均可食率为97.71%.对入选的12株壶瓶枣优树的10个性状指标进行统计分析,发现优树表现出显著的变异特征,这种变异将为优树的综合评价、优中选优提供丰富的物质基础。     

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.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

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.     

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.     

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.     

Boron in forest trees and forest ecosystems

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.     

Survival and Growth of Picea abies Regeneration after Shelterwood Removal with Single- and Double-grip Harvester Systems

Three stands in Sweden were followed for 7 yrs to study the survival and growth of Norway spruce [Picea abies (L.) Karst.] regeneration after shelterwood removal with single- and double-grip harvester systems. The height of all seedlings within circular plots was recorded before and after final cutting. The tallest seedling and one randomly selected seedling on each circular plot were permanently marked and their annual height growth was measured each year during the period 1993-1999. No significant differences between single- and double-grip harvester systems were found with respect to their effects on regeneration density, survival or annual height growth. The annual height growth of the individual seedlings after shelterwood removal was significantly correlated with seedling height before shelterwood removal. Significant differences were found in annual height growth between seedlings with high and low vitality. Logging damage did not affect the annual height growth. Several practical conclusions were drawn. First, the choice of harvester system does not affect seedling height growth or survival after shelterwood removal. Secondly, the removal of a 200 m³ shelterwood with 200 stems ha^-1 does not seem to constitute a serious problem for seedling survival and growth. Finally, estimated vitality and seedling height both seem to be fairly good predictors of postrelease survival and growth.     

Development of Pinus sylvestris Main Stems Following Three Different Precommercial Thinning Methods in a Mixed Stand

Reducing competition by point cleaning may be an attractive alternative to conventional precommercial thinning in forestry. In this study, survival and development of main stems of Scots pine (Pinus sylvestris L.) following point cleaning were examined in a mixed stand of mainly Scots pine and birch (Betula pendula Roth and Betula pubescens Ehrh.) in northern Sweden. Treatments studied were: no precommercial thinning, conventional precommercial thinning, point cleaning of all secondary stems, and point cleaning of only the secondary stems that were higher than the main stem, within a radius of 0.8 m from the main stem, respectively. A randomised complete block design with three replicates was used. Measurements taken 13 growing seasons after these treatments showed that conventional precommercial thinning was the best treatment for retaining Scots pines as main stems. However, conventional precommercial thinning resulted in the poorest timber quality of the remaining Scots pines in terms of stem taper, thickest branch diameter and relative live crown height. In conclusion, point cleaning has to be followed by a complementary cleaning operation if the objective is to retain Scots pines as main stems in such mixed stands.