Importance of rubberwood in wood export of Malaysia and Thailand

We examined the contribution of rubberwood to the timber export markets of Malaysia and Thailand. In Malaysia, rubberwood has grown from 26% of total exported wood products in 1998 to 35% in 2007. A high proportion of furniture products (80%) is rubberwood, whereas the contribution of rubberwood to other wooden products is less than 20%. Only 10% of sawn timber and logs is rubberwood. In Thailand, rubberwood contributes to around 60% of total exported wood products, arising from a high share of not only furniture products (70%) but also other wood products (around 50%) and sawn timber and logs, which have increased in share from 40% in 1998 to 79% in 2007. We conclude that the high proportion of rubberwood products in the wood export markets of these two countries is a result of: (1) scarcity of raw wood materials because of strict controls on the logging of natural forests; and (2) governmental support to rubberwood production, including financial support to rubber planters and technical assistance to downstream timber processors.     

Micromorphology of abnormal and decayed xylem in rubberwood canker

Typical symptoms of rubberwood canker found in East Kalimantan, Indonesia, differ from those of conventional rubberwood peach canker. Rubberwood canker showed a conspicuous longitudinal canker with exposed xylem that was discolored and decayed. Bark wounds, resulting from regular tapping, were enclosed within the xylem, and the tissues had become integrated. The characteristics of abnormal and decayed xylem in this rubberwood canker were analyzed by light microscopy and scanning electron microscopy. Xylem in the vicinity of the enclosed bark contained fewer vessels of smaller diameter and shorter length, and significantly wider rays compared with normal xylem. Around the wide growth zones of the canker, axial cells were disoriented and warped toward the canker zones. In view of the separation among cells, and the concentric degradation of the cell walls starting from the lumen surfaces, decayed xylem appeared to be caused mainly by white-rot fungal attack.     

糠醇化对橡胶木性质的影响

以平衡含水率(EMC)和线性湿涨系数(LSC)为评价指标,研究了不同质量增加率(WPG)的糠醇改性对橡胶木吸湿尺寸稳定性的影响,并从尺寸稳定性角度探讨糠醇改性的临界WPG;还分析了糠醇改性对抗弯强度(MOR)和抗弯弹性模量(MOE)的影响,并探讨了减量平衡含水率(EMCR)衡量浸渍改性材吸湿性的可行性.结果表明:糠醇化可以显著降低橡胶木的EMC和LSC,EMC受WPG的影响明显,LSC随着WPG的增加而显著下降,基于LSC和胞壁充涨系数推导的临界WPG两者之间存在较大误差;改性材的MOE随WPG提高而增加,增幅约在30％ ～40％,但MOR却略有下降;与基于浸渍材绝干质量的EMC相比,基于浸渍前绝干质量的EMCR能更客观地评价浸渍改性后木材的吸湿能力,可用于吸湿性的研究中,但鉴于用户和第三方检测不方便,不推荐其作为改性产品的评价指标.     

印象柬埔寨

在写这篇关于柬埔寨的文章的时候,我突然想到了汉字中“凹、口、凸”这几个象形文字,冥冥中这三个意象似乎对应着柬国的人文历史。在下笔之后,突然发现这本该是游记的轻松文章已经不可控制地走向了沉重和严肃……     

农户生产效率及测度研究--以安徽省金寨县为案例

引言森林资源和林业发展在中国南方集体林区中发挥着重要作用。中国南方集体林区林地面积和森林蓄积占全国的比重分别为38.40%和17.79%,人工林面积和蓄积占全国的比重分别为54.40%和52.02%(国家林业局,2000)。1978年以来,实行了家庭联产承包责任制以后,重新恢复家庭作为农村生产与生活的基本单位,由集体化向以家庭为基本生产单位的转变视为制度创新。这个制度安排是否导致经济效率和总要素生产率发生了变化?如果发生了变化,是如何变化的?变化程度有多大?与此同时,森林资源丰富的中国南方集体林区的经济效率是否发生了变化,变化程度如何?生产…     

柬埔寨吴哥植物资源调查研究

柬埔寨位于东南亚中南半岛南部,覆盖大面积热带雨林,是个美丽富饶的国家,被称为"富贵真腊"。通过参考有关资料和实地勘察,调查柬埔寨吴哥的植物资源种类。结果表明:柬埔寨的植物资源丰富、种类繁多且分布广泛,约有1.5万种;山区分布着常绿阔叶林和松林,北部平原有龙脑香林,东部平原有草地和落叶林,沿海分布着红树林。分析吴哥的植物调查情况,提出应进行合理开发和生态保护。     

Superheated steam treatment of rubberwood to enhance its mechanical,physiochemical, and biological properties

ABSTRACT

This research was aimed to investigate mechanical properties, color and cell-wall components changes, and durability of pre-dried rubberwood (Hevea brasiliensis) after superheated steam (SS) treatment. Wood samples were treated at different SS temperatures (140–180°C) for 1–3?h. The highest compression strength parallel-to-grain, hardness and impact strength were found for samples treated at 160°C for 3?h (30.7% higher than untreated), at 150°C for 1?h (26.6% higher than untreated) and at 150°C for 2?h (52.6% higher than untreated), respectively. The surface color became darker after each treatment in comparison with the untreated wood. The number of accessible hydroxyl groups decreased and the relative cellulose crystallinity increased with SS temperature, indicating decreased hygroscopicity of the treated wood. Also, SEM micrographs of wood surface showed consistent decrease in starch particles with treatment temperature. Both decay and termite resistances of treated rubberwood improved with treatment temperature. All the analyzes showed that dried rubberwood treated with SS had some improvements in the mechanical properties, decreased hygroscopicity, and increase resistance to decay.     

柬埔寨吴哥人文和自然景观调查研究

通过实地考察柬埔寨吴哥并查阅有关资料,研究其人文和自然景观,并加以审美思考。吴哥遗迹群被誉为"东方四大奇迹"之一,是柬埔寨的国宝。其修复模式取得较好的效果,可为我国乃至国际上历史遗存的保护提供借鉴。     

农户生产效率及测度研究(续)--以安徽省金寨县为案例

2.联合生产效应分析根据随机前沿生产函数回归结果计算农户生产要素对林业生产弹性计算结果见表5。表5中计算结果分为包含制度因素和不包含制度因素两个方案,两个方案中农牧业产值对林业产值的弹性均为正值,也就是说,农牧业产值的增长能够带来林业产值的增长,二者之间的弹性系数大于1,农牧业产值增长1个百分点,则林业增长超过一个百分点,具有相互推动作用表明金寨县并不存在林牧矛盾。两个方案比较,包括制度因素方案的弹性系数小于不包括制度因素的弹性系数,1978年、1980年、1985年、1990年1995年、1996年和1997年,不包含制度因素方案与包括…     

Nitrogen deposition and release pattern of slow release fertiliser made from urea-impregnated oil palm frond and rubberwood chips

The fertiliser industry faces a continuing challenge to improve the efficiency of their products, particularly of nitrogenous fertilisers, and to minimise adverse impacts. Therefore, a new slow release fertilizer, ureaimpregnated woodchips from tropical plant biomass(oil palm frond and rubberwood), was developed. The morphology of the impregnated woodchips was investigated by scanning electron microscopy and the success of impregnation of urea and nitrogen deposition into the woodchips was confirmed by energy dispersive X-ray spectrometry.When nitrogen release patterns from impregnated woodchips fertiliser were simulated using a soil solution and distilled water as leaching solutions in a static condition for 768 h, release was slow and steady, although the release rate was lower in distilled water than in the soil solution.     

Comparison of soil physical properties in evergreen and deciduous forests in central Cambodia

We investigated soil physical properties in three forest types in tropical lowland monsoon forests in central Cambodia under the same climatic conditions, i.e., Kanhaplic Haplustults in dry evergreen forest (KH-E), Arenic Haplustults in dry deciduous forest (AH-D), and Arenic Ultic Alorthods in mixed evergreen–deciduous forest (AA-M), to clarify the relationship between forest types and soil physical properties. The clay content was correlated with water content at ψ = −9.8 and −1500 kPa (WC10 and WC1500), available water capacity (AWC), and the van Genuchten (vG) parameter N (P < 0.01). vG parameter N was in the order AH-D > AA-M > KH-E whereas vG parameter α had a high value in KH-E soil at 0–100 cm in depth. The cumulative AWC (AWCcl, mm) at a soil depth of 0–200 cm was higher in the AH-D than in the KH-E, and was not considered a major factor affecting the distribution of different forest types under the same climatic conditions. The unsaturated hydraulic conductivity (K) at 0–100 cm in depth, estimated by use of models, was higher in AH-D than in KH-E mostly at matric potential ψ > −10 kPa. The low K in KH-E at ψ > −10 kPa was considered favorable for evergreen trees to retain the soil water for the transpiration in the dry season, and the matric potential in KH-E showed more gentle decreases in the early dry seasons than AH-D. Thus the differences in K among generally sandy soil types could possibly affect the establishment of different forest types in the study area with the same climate.     

Wood-boring beetles (Coleoptera: Bostrichidae,Curculionidae; Platypodinae and Scolytinae) infesting rubberwood sawn timber in southern Thailand

Species diversity and infestation densities of rubberwood (Hevea brasiliensis Müll. Arg.)-boring beetles at sawmills in southern Thailand were investigated during July 2007 and March 2008. Twenty-two species of wood-boring beetles, nine bostrichids, eight scolytines and five platypodines, were identified. The powder post beetle, Sinoxylon anale Lesne (40%), is the single dominant rubberwood pest in the studied area. Other frequently captured species are Sinoxylon unidentatum (Fabricius) (18%), Heterobostrychus aequalis (Waterhouse) (10%) and Lyctoxylon dentatum Lesne (9%). The Shannon diversity index of rubberwood-boring beetles in the eastern coastal area was significantly (p < 0.01) greater than that in the western coastal area. The infestation density in the dry season was significantly higher than that in the wet season, but there were no significant differences between eastern and western coastal areas.     

Estimation of litter fall and seed production of Acacia mangium in a forest plantation in South Sumatra, Indonesia

Annual litter fall of Acacia mangium in the period of September 1995 to August 1996 was estimated at 5939 kg ha⁻¹ year⁻¹ and from September 1995 to August 1996 at 6048 kg ha⁻¹ year⁻¹, with the highest seasonal production in the dry season. The litter fall was dominated mainly by leaves, 4446 kg (75%) and 4137 kg (68%), respectively. Seed production in the litter fall was estimated at 42.4 kg ha⁻¹ year⁻¹ (4.1 million seeds ha⁻¹) and 39 kg ha⁻¹ year⁻¹ (3.8 million seeds ha⁻¹), with the highest in the dry season from June to October. The accumulated litter fall in the forest floor together with shrubs and grass provide a high fuel load, increasing fire risk.     

Radial variation of wood cell features under different stocking densities management of two new clones of rubberwood (Hevea brasiliensis)

Wood characteristics vary from pith to bark and this can influence the final use. These variations can be related to the effects of plantation management. The radial variation in fiber cells, vessel elements, and ray cells was investigated for a commercial and fast-grown species, the rubberwood (Hevea brasiliensis), at varying stocking densities. Nine-year-old trees of two new clones (RRIM 2020 and RRIM 2025) were categorized into four stocking densities of 500, 1000, 1500, and 2000 trees ha^?1. The sample blocks were anatomically analyzed to determine the changes in wood cells from pith to bark. The results generally showed a centrifugal increase in fiber features, vessel diameter, ray height, and ray area. Vessel density and ray density showed a decreasing trend. Vessel areas revealed a radial irregular variation. The ray area showed a striking relationship with ray density and ray height. Ray cell pattern indicated enough variation for visual approval to ensure within and between stocking density changes. Most radial variation was explained by the effect of cambial age. Owing to different stem width and growth rates, the mean cell features were not at the same radial distances from the pith.     

土著竹种在柬埔寨暹粒省社区林业发展中的应用前景

柬埔寨拥有较丰富的竹类资源,且有较多的传统利用,但竹类资源在社区林业建设中没有得到足够重视。暹粒省面临着经济发展和森林资源匮乏突出矛盾,发展社区林业是缓解这一矛盾的重要途径。当地土著竹种在社区林业发展中具有多方面的优势,应成为发展社区林业的首选树种。     

Carbon emissions due to land-use change and logging in Cambodia: a modeling approach

Land-use change and forestry in the tropics have caused huge carbon emissions to the atmosphere. The magnitude of these emissions, however, remains debatable. Therefore, there is a need to further develop appropriate methods that would reduce the estimation uncertainties. From a modeling perspective, this report is aimed at estimating carbon emissions from deforestation and logging activities in Cambodia just after it opened its door to the world. Recently available land-use and forest inventory data were used to develop simple models capable of estimating the change of carbon stocks in, and carbon emissions from, dryland and edaphic forests. This study estimated the annual deforestation rate to be 0.1 million ha between 1973 and 2003, or about 0.7%. Between 1993 and 2003, annual carbon emissions amounted to about 13.7 TgC, owing to deforestation and logging. The emissions calculated here are higher than those reported by the Cambodian government, which claimed that Cambodia was once a net sink of carbon. The models developed in this study will be a useful tool for further study of carbon emissions in tropical countries where selective logging is practiced. Part of this article was presented at the International Symposium on the Role of Forests for Coming Generations: Philosophy and Technology for Forest Resource Management, October 2004, Utsunomiya, Japan     

柬埔寨南亚松松香和松节油的化学组成特征

采用气相色谱和质谱法对柬埔寨南部地区的南亚松松香和松节油的化学组成特征进行研究.采用水蒸气蒸馏法将南亚松松脂分成松节油和松香两个馏分后,分别对松香和松节油中所含成分进行定性和定量测定,松脂中的含油量为20.67%.在松香馏分中共检出9个化合物,其中海松酸型树脂酸占49.59%,枞酸型树脂酸占37.18%,二元酸占12.40%.主要的树脂酸为异海松酸、8(9)-异海松酸、枞酸和南亚松酸,分别占松香馏分的20.90%、21.14%、23.45%和12.40%.松节油馏分中检出16种化合物,其中单萜类化合物13种,倍半萜类化合物2种,二萜类化合物1种.单萜类化合物占松节油量的99.49%,其中间(廾孟)-4,8-二烯、小茴香烯和别罗勒烯,分别占松节油量的24.01%、29.21%和23.71%.研究发现该松香中枞酸型树脂酸量小于海松酸型树脂酸,同时在松香中还检出了2-甲基-5-异丙基-双环[3.1.0]-己-2-烯、间(廾孟)-4,8-二烯、α-水芹烯、小茴香烯、4-蒈烯、别罗勒烯、9,10-二氢环异长叶烯等7种化合物,而未发现α-蒎烯的存在.     

碳源排碳量估算办法研究进展

本文对碳源排碳量估算中相关问题的研究及其进展做了系统的阐述。在碳源的分类的基础上,着重讨论了碳源排碳量的测算办法、排碳量估算中的不确定性,并介绍了如何提高估算的精确性等相关问题。