Casuarina Coastal Forest Shelterbelts in Hambantota City, Sri Lanka: Assessment of Impacts

Growing of Casuarina equisetifolia as a small shelterbelt on the beach in Hambantotota City was implemented to protect the beautiful natural sand dunes, preserve visual amenity and be a barrier to seawater salt spray. The casuarina shelterbelt has become popular because it was the only undamaged area in Hambantota City after the devastating 2004 tsunami. The objective of the study was to assess the impacts of the casuarina shelterbelt in economic, social and environmental terms. A survey was conducted to elicit observations and experiences of city dwellers close to the shelterbelt. Respondents did not consider that the shelterbelt reduced wind speed. Although the belt has increased the size of the sand dunes, the casuarina trees have suppressed the growth of native species as an under-storey. The belt has improved the aesthetic value of the beach. No impact of the shelterbelt has been identified in protecting agricultural crops and reducing the corrosion of household goods from seawater salt spray. The city dwellers have not recognized the economic importance of casuarina timber but are impressed with the increase of fuelwood supply from the shelterbelt. The shelterbelt has prevented illegal settlement, but facilitated anti-social and illegal activities among lawless city dwellers. The attractiveness of the beach for tourism has been enhanced. Empirical evidence reveals that the casuarina belt in Hambantota City has greater environmental and social impacts than economic impacts.     

我国珍贵树种柚木人工林发展现状、对策与展望

简述了世界柚木资源及人工林发展概况,重点回顾了我国柚木引种历史、人工林发展状况以及柚木遗传改良研究,提出了我国柚木人工林发展存在的技术问题和解决对策,展望了柚木国内外市场和我国柚木人工林发展前景。     

Liming and Boron in a Teak Crop Established during Early Stages in an Acid Soil

Cultivation of a teak crop in acid soils needs adequate agronomic management of these characteristics of high acidity and low nutrient supply to obtain high yields in wood. This work evaluated the effect of liming and application of boron in teak plants during early stage of growth in acid soils from Córdoba, Colombia. The experiments were conducted in the greenhouse and soils laboratory of the Faculty of Agricultural Sciences by using acid soil limed with calcium hydroxide (Ca(OH)₂) and fertilized with boron. The treatments were chosen according to the Box Bernard augmented matrix 3, with dosages of Ca(OH)₂ from 300 to 5700 kg ha^?1 and boron from 0.3 to 5.225 kg ha^?1, using three repetitions per treatment. Data obtained on boron in the soils (Bs) and in the plant (Bp), foliar area (AF), leaf dry mass (MSH), and roots (MSR) were analyzed through means tests and regressions from response surfaces (p ≤ 0.05). The results indicated increased pH and in the soil’s exchangeable calcium (Ca). To reach the maximal AF, the dosages of 2.26 kg ha^?1 of boron (B) and 4522.6 kg ha^?1 of Ca(OH)₂ were estimated; for MSH, stem, and roots boron, dosages ranged between 2.02 and 5.225, with the dosage of 5700 kg ha^?1 of Ca(OH)₂ in all the variables evaluated. Application of calcium hydroxide also showed positive effect in leaf, stem, and MSR gain of teak seedlings during early growth stages. Fertilization with boron (B) did not show significant effect upon growth of dry masses of the parts evaluated.     

Assessment of enrichment planting of teak (Tectona grandis) in degraded dry deciduous dipterocarp forest in the Central Highlands,Vietnam

After years of unsustainable logging, dry deciduous dipterocarp forest (DDDF) has become poor in timber stocks and has been converted to industrial crops such as rubber. The objectives of this study were to assess teak (Tectona grandis L.f.) tree establishment under degraded DDDF conditions and to determine factors that influence the suitability of teak as a forest enrichment tree species. A set of 64 experimental plots of 4 900 m² each was set up and observed for 4–5 years for testing enrichment planting with teak under various combinations of two groups of factors: ecological conditions and forest status. Weighted, non-linear, multivariate regression models were used to detect key factors that influenced the suitability of teak. The results showed that at the age of 4 years the average dominant tree height (defined as 20% of the tallest trees in the experimental plot) reached 11.2, 7.8, 5.3 and 3.8 m for very good, good, average and poor suitability levels, respectively. Survival rates of planted teak from average to very good suitability levels were over 90%. Six key factors that affected the suitability of teak were waterlogging during the rainy season, altitude, stand volume of the degraded DDDF, soil type, percentage of sand and concentration of P₂O₅ in the soil. Under the extreme ecological and environmental conditions of the DDDF, enrichment planting with teak gave promising results.     

基于组子细工的珍贵树种余料再利用设计研究——以小径柚木为例

以珍贵树种小径柚木为例,简述了余料的来源与特点;介绍了组子细工的历史由来及常用组子纹样类型;重点从组子细工的角度阐述了小径柚木余料再利用设计原则及方法,并运用实例分析了组子细工的设计应用。余料再利用不仅利于提高木材利用率,对传统手工木作文化的传承与发展也具有积极意义。     

Genetic and morphological variation in natural teak （Tectona grandis） populations of the Western Ghats in Southern India

Teak(Tectona grandis L.f.) is a popular hardwood species native to South and South-East Asia. The possible association of amplified fragment length polymorphism(AFLP) marker with morphological variables of eleven important characters viz. girth at breast height(GBH), height of tree, bole height, branch knots, presence of fluting, spiral stem, leaf hair, leaf length/breadth ratio, branching pattern, bark colour and petiole shape for nine natural populations comprising 180 genotypes of teak(9 populations × 20 trees). The phenogram constructed using Euclidean distances for the eleven morphological characters showed that the populations were not grouped according to their geographical origin. The Mantel's test for pairwise correlation between Euclidean distances of different morphological variables and genetic distances from AFLP data revealed that only petiole character(r =0.269; p =0.046) and height of tree(r =0.200; p =0.001) were significantly correlated with that of AFLP data matrix. The nine populations in this study covered a geographic area of about 1000 km stretch along the Western Ghat of South India. A test of correlation between genetic and geographic distance matrices revealed a significant positive correlation(r =0.475; p =0.009). The lack of perfect congruence between morphological and molecular data except for geographic distance, tree height and petiole character suggested that the morphological system might be useful for the morphotypes management but not appropriate to study the genetic structure of the teak populations.     

微波等离子体处理对柚木表面润湿性的影响

改善木材表面润湿性可显著提高其胶合性能,进而提高木质复合材料的物理力学性能。采用微波等离子体对柚木木材进行了表面处理,通过测量微波等离子体处理前后的液体接触角及计算表面自由能来评价表面润湿性改善的效果。试验结果表明:试件距反应腔120mm时处理效果略好于试件距反应腔80mm时的效果,短时间微波等离子处理即可降低柚木表面接触角,提高表面自由能。反应距离为120mm,由水作为试液所测的接触角降幅最高可达74%。     

柚木种源主要性状聚合遗传值的评价

采用聚合遗传值法，对９年生的印度、泰国、缅甸、尼日利亚等柚木种源９种性进行评价，结果表明，除保存率外，各种性在种源之间存在显著至极显著差异，并主要受遗传所控制。生长的虫晚期呈紧密相关表明：对苗高进行汰劣性选择和在幼林生长初期作种源的生长评价，具有一定价值。