鲁东南滨海园林植物资源和耐盐性调查分析

在野外调查和文献查阅相结合的基础上,通过对鲁东南滨海植物的调查及绿化植物耐盐碱能力的分析研究,编制出鲁东南滨海地区野生植物名录,并根据植物生长状况和立地条件对园林绿化植物的耐盐碱能力进行分类,筛选出适合该区园林绿化的植物。调查结果表明:1)鲁东南滨海地区的绿化植物共61科174种,其中已用于园林绿化的植物37科83种,包括裸子植物3科8种,被子植物34科75种;野生植物31科91种;可大力推广的园林绿化植物47种。2)野生植物中可用于园林绿化的共5种,已用于园林绿化但鲁东南滨海没有引种的植物4种,还有1种濒危物种和2种外来入侵物种。     

秦皇岛滨海地区春季观花植物观赏特征分析

通过查阅文献及实地调研,对秦皇岛滨海地区春季观花植物进行调查与分析,结果表明:秦皇岛滨海地区园林应用的春季观花植物有73种,以观花灌木种类最多;应用频度超过80%的春季观花木本植物共12种,应用频度低于40%的有27种,园林开发应用潜力巨大;花期时序多集中在4月,春季植物景观效果最好;植物花色以红粉色系为主。通过对比秦皇岛滨海地区与北京地区春季观花植物及景观特点,从整体分区、分段配置、主配分明、乡土优先等方面对秦皇岛滨海地区春季观花植物景观营造进行了探讨。     

秦皇岛滨海地区夏季观花植物观赏特征分析

通过实地调研及查阅文献,对秦皇岛滨海地区夏季观花植物资源进行调查与分析。结果表明:秦皇岛滨海地区园林应用的夏季观花植物有62种,以地被植物种类最多;应用频度超过40%的夏季观花木本植物共14种,但乔木应用较少;花期时序多集中在6月,夏季植物景观7月整体效果最佳;植物花色以白色和蓝紫色为主。最后,对秦皇岛滨海地区夏季观花植物景观营造技术进行了讨论。     

秦皇岛滨海地区野生药用盐生植物园林应用研究

以秦皇岛滨海地区野生药用盐生植物资源调查为基础,对其中23种具有较高观赏价值、生态价值的植物观赏特性及园林应用形式进行分析,提出了利用野生药用盐生植物构建多层次稳定的植物景观,探讨了特色景观建设的几种模式,可为滨海特色景观建设和实现景观可持续发展提供参考.     

天津滨海野生观赏盐生植物资源调查与园林应用

在野外调查和文献查阅相结合的基础上,对天津滨海野生盐生植物资源进行了调查与分析,筛选出40多种具有较高观赏价值的盐生植物,并对其园林观赏特性及园林应用形式进行深入分析,为滨海的景观建设奠定有利基础。     

广西北海涠洲岛植物资源调查研究

对涠洲岛上的植物资源进行调查研究,统计结果表明,该岛植物资源丰富,共有131种,隶属于77科121属,其中蕨类植物2科3属4种,裸子植物1科1属1种,被子植物74科117属126种。植物构成体现滨海特色、风水林文化特色等,大多数种类具有较高观赏价值和生态价值,对其生态特性及绿化应用进行分析,为滨海地区的绿化建设提供参考。     

大连长兴岛北滨海路绿化带植物结构特征研究

该文调查大连长兴岛北滨海路绿化带植物的种类和分布现状,采用物种重要性指数、物种重现率、物种多样性指数等分析其整体结构特征,并对长兴岛北滨海路绿化植物的配置和应用进行了讨论,为进一步优化滨海路绿化结构,提升植物景观的层次多样性和美观程度提供参考。     

黄河三角洲滨海盐碱地绿化植物资源普查及选择研究

以我国滨海盐碱地的典型代表之一——黄河三角洲为工作点,通过对该地区绿化植物的普查和统计,根据植物生长状况及其立地条件,对该区绿化植物的耐盐碱能力进行分析研究,编制出黄河三角洲野生植物名录和黄河三角洲园林植物耐盐碱性分类表。并在此基础上,考虑到黄河三角洲的土壤、水文特点及园林绿化的制约因素,结合已经实践证明能在该区良好生长的园林植物,分析研究野生植物及其在园林绿化上的应用,联系经济效益、生态效益、社会效益,提出滨海盐碱地绿化植物资源在不同条件下的最佳选择。     

广东省滨海乡土耐盐植物资源及园林应用研究

通过实地调查和文献查阅,对广东省滨海耐盐的乡土植物资源进行整理和总结。结果表明,广东省共有野生海岸耐盐植物240种,隶属84科,大多处于尚待开发状态;结合耐盐程度、适应性和观赏特点等各项指标评价,优选46种植物推荐应用于滨海景观带或防护林建设。分析广东省滨海绿化现状,提出海滨耐盐植物开发利用的建议,建立耐盐乡土植物专类苗圃,并为海滨绿化配置多层次多树种的群落结构。     

海滨植物盐度适应性研究进展

滨海植物是城市绿化美化、海岸线生态保护的重要组成部分，其能在滨海极端气候下生存，具备较强的耐盐能力。本文介绍了盐生植物的分类，又重点阐述了植物耐盐的生理生态适应性机制，从植物形态特征变化、生理生化调节等方面总结了滨海植物的盐度适应性特征，为耐盐植物引种、驯化、培育和筛选提供依据，为恢复沿海生态系统，保护红树林、滩涂及海草资源提供参考。     

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.