• 제목/요약/키워드: Tropical forest

검색결과 192건 처리시간 0.026초

철도 폐침목의 크레오소오트유 잔류 및 재질 특성 (Wood Properties and Residual Creosote Oil of Disused Railway Wood Ties)

  • 이종신;박종영
    • 농업과학연구
    • /
    • 제37권3호
    • /
    • pp.465-469
    • /
    • 2010
  • In order to develop effective recycling technologies of disused railway wood ties, wood properties and residual creosote oil of wood ties were investigated. Among the total 50 wood ties, 32 wood ties were identified as tropical hardwood tree, such as, Keruing (Dipterocarpus spp.), Kempas (Koompassia malaccensis), Kapur (Dryobalanops spp.) Naytoh (Palaquium rostratum), and so on. Disused wood ties showed mostly sound structure without degradation of cell walls by decay fungi. Disused wood ties showed high strengths of bending and compressive parallel to grain because degradation of wood properties was hardly occurred in use under exterior condition. Disused railway wood ties had relatively poor depth of penetration and residual of creosote oil because of refractory wood structures. These results suggest that disused railway wood ties may be useful as recycling wood wastes.

A review on thermomechanical properties of polymers and fibers reinforced polymer composites

  • Saba, N.;Jawaid, M.
    • Journal of Industrial and Engineering Chemistry
    • /
    • 제67권
    • /
    • pp.1-11
    • /
    • 2018
  • Polymer composites offered broad engineered applications, however their diversity get restricted owing to fluctuations in thermomechanical properties during heating or cooling hence great concern required prior their applications through thermomechanical analysis (TMA). Traditionally, TMA or dilatometry found to be simple, ideal, reliable, sensitive, excellent and basic thermal analytical technique. TMA provides valuable information on thermal expansion, glass transitions temperature (Tg), softening points, composition and phase changes on material of having different geometries simply by applying a constant force as a function of temperature. This compilation highlights the basics and experimental of TMA for both research and technical applications and also provide literature on TMA of polymers, hybrid composites, nanocomposites and their diverse applications.

Species Composition and Stand Structure of Natural Forest, Timber-harvested Forest and Degraded Forest in the Bago Yoma Region of Myanmar

  • Oo, Thaung Naing;Lee, Don Koo
    • 한국산림과학회지
    • /
    • 제96권5호
    • /
    • pp.572-579
    • /
    • 2007
  • Tree species diversity is an important aspect of forest ecosystem stability. Tree species inventories at defined sites and in minimum diameter classes give a reliable indicator of the diversity level as well as the structural stability level of a study site. This study was conducted to investigate the species composition and the stand structure of the natural forest, timber-harvested forest (logged-over forest) and degraded forest of the Oak-twin Township in the Bago Yoma Region of Myanmar. Natural forest showed the highest family and species richness in all the investigated forests. At the family level, Verbenaceae occupied the highest importance value index (IVI) in all the forest stands while teak (Tectona grandis Linn. f.) occupied the highest IVI at the species level. However, the small diameter classes of T. grandis and other commercial species were less than those of big diameter classes in all the investigated forests. This abnormal pattern of diameter distribution could be a problem for the sustainable production of commercial timber species in the near future.

Acacia mangium Willd. - A Fast Growing Tree for Tropical Plantation

  • Hegde, Maheshwar;Palanisamy, K.;Yi, Jae Seon
    • Journal of Forest and Environmental Science
    • /
    • 제29권1호
    • /
    • pp.1-14
    • /
    • 2013
  • Acacia mangium is an evergreen fast-growing tropical tree, which can grow up to 30 m tall and 50 cm thick, under favorable conditions. It is a low-elevation species associated with rain forest margins and disturbed, well-drained acid soils. It is native to Papua, Western Irian Jaya and the Maluku islands in Indonesia, Papua New Guinea and north-eastern Queensland in Australia. Due to its rapid growth and tolerance of very poor soils, A. mangium was introduced into some Asian, African and western hemisphere countries where it is used as a plantation tree. A. mangium has good quality wood traits, such as a comparatively low proportion of parenchymatous cells and vessels, white and hard wood, and high calorific value. Therefore, it is useful for a variety of purposes, such as furniture, cabinets, turnery, floors, particleboard, plywood, veneer, fence posts, firewood, and charcoal. It is also being used in pulp and paper making because it has good pulp traits, with high yields of pulp, quality of kraft, and produces paper with good optical, physical and surface properties. Because there are significant provenance differences in growth rate, stem straightness, heartwood formation and frequency of multiple leaders, the productivity and quality also varies depending upon environmental conditions, so genetic improvement programmes have been undertaken in countries like Australia, India, Indonesia, Malaysia, the Philippines, Taiwan and Thailand. The programme includes provenance identifications and testing, plus tree selection and clonal multiplication, establishment of seed orchards and hybridization. The phenology, reproductive biology, fruit characteristics, silvicultural practices for cultivation, pest and diseases problems, production of improved planting stock, harvesting, wood properties and utilization have been discussed in this paper.

Modeling the Natural Occurrence of Selected Dipterocarp Genera in Sarawak, Borneo

  • Teo, Stephen;Phua, Mui-How
    • Journal of Forest and Environmental Science
    • /
    • 제28권3호
    • /
    • pp.170-178
    • /
    • 2012
  • Dipterocarps or Dipterocarpaceae is a commercially important timber producing and dominant keystone tree family in the rain forests of Borneo. Borneo's landscape is changing at an unprecedented rate in recent years which affects this important biodiversity. This paper attempts to model the natural occurrence (distribution including those areas with natural forests before being converted to other land uses as opposed to current distribution) of dipterocarp species in Sarawak which is important for forest biodiversity conservation and management. Local modeling method of Inverse Distance Weighting was compared with commonly used statistical method (Binary Logistic Regression) to build the best natural distribution models for three genera (12 species) of dipterocarps. Database of species occurrence data and pseudoabsence data were constructed and divided into two halves for model building and validation. For logistic regression modeling, climatic, topographical and edaphic parameters were used. Proxy variables were used to represent the parameters which were highly (p>0.75) correlated to avoid over-fitting. The results show that Inverse Distance Weighting produced the best and consistent prediction with an average accuracy of over 80%. This study demonstrates that local interpolation method can be used for the modeling of natural distribution of dipterocarp species. The Inverse Distance Weighted was proven a better method and the possible reasons are discussed.

고립지역의 산림자원 활용에 관한 고찰 (A Study on Use of Forest Resources in the Isolated Areas)

  • 이성기;이갑연;안영희
    • 한국환경과학회지
    • /
    • 제13권3호
    • /
    • pp.181-187
    • /
    • 2004
  • In case an average accumulation of the investigated area is 200$m^{3}$/ha with cutting age of 80 years applied, annual workload will be 77ha and require 5 teams; each team consisting of 5 persons, enabling stabled supply of lumbers of 15,500$m^{3}$ every year. If one cutover is less than 2ha with cutting age of 80 years applied, it's possible to protect the peculiar ecology and secure stabled labor, workload and lumbering. It may become model forest out of tropical forest management which is controversial all over the world. Of course this presupposes construction of access roads.

Sciaphila secundiflora Thwaites ex Benth. (Triuridaceae): An unrecorded species from Korean flora

  • Yim, Eun-Young;Hyun, Hwa-Ja;Kim, Chang-Uk;Kim, Chan-Soo
    • 식물분류학회지
    • /
    • 제47권3호
    • /
    • pp.196-198
    • /
    • 2017
  • Sciaphila secundiflora occurs on Jeju Island as a second species of the genus Sciaphila in Korea. This is an important finding in relation to the flora of Korea, as species of the genus Sciaphila are concentrated mainly in Indonesia and Malaysia. Few species are found on the mainland of Asia, in Japan, Taiwan, China (Hainan), tropical Africa, Australia, and on the Pacific islands. In this paper, the species S. secundiflora is described and illustrated as a new record from Korea. In addition, we suggest that the species of the genus Sciaphila should be protected with regard to its habitat characteristics and for its phytogeographic and climatic significance.

응력파(應力波) 측정(測定)에 의(依)한 수종(數種)의 국산(國産) 침엽수재(針葉樹材) 및 열대(熱帶) 활엽수재(闊葉樹材)의 휨성질(性質) 평가(評價) (Evaluation of Static Bending Properties for Some Domestic Softwoods and Tropical Hardwoods Using Sonic Stress Wave Measurements)

  • 이도식;조재성;김규혁
    • Journal of the Korean Wood Science and Technology
    • /
    • 제25권1호
    • /
    • pp.8-14
    • /
    • 1997
  • Stress wave velocity, wave impedance, and stress wave elasticity of small, clear bending specimens of five domestic softwoods (Pinus densiflora, Pinus koraiensis, Chamaecyparis obtusa, Cryptomeria japonica, and Larix leptolepis) and four tropical hardwoods(Kempas, Malas, Taun, and Terminalia) were correlated with static bending modulus of elasticity(MOE) and modulus of rupture(MOR). The degree of correlation between stress wave parameters and static bending properties was dependent on wood species tested. Stress wave elasticity and wave impedance were better predictors for static bending properties than stress wave velocity for each species individually and for softwood or hardwood species taken as a group, even though elasticity and impedance were nearly equally correlated with static bending properties apparently. Based upon the correlation coefficient between stress wave parameters and static properties, stress wave elasticity and wave impedance were found as stress wave parameters which can be used for the purpose of the reliable and successful prediction of bending properties. The degree of correlation between static MOE and MOR was also different according to wood species tested. Static MOE was nearly as well correlated with MOR as was stress wave elasticity. The results of this research are encouraging and can be considered as a basis for further work using full-size lumber. From the results of this study, it was concluded that stress wave measurements could provide useful predictions of static bending properties and was a feasible method for machine stress grading of domestic softwoods and tropical hardwoods tested in this study.

  • PDF

Rapid and Efficient Detection of 16SrI Group Areca Palm Yellow Leaf Phytoplasma in China by Loop-Mediated Isothermal Amplification

  • Yu, Shao-shuai;Che, Hai-yan;Wang, Sheng-jie;Lin, Cai-li;Lin, Ming-xing;Song, Wei-wei;Tang, Qing-hua;Yan, Wei;Qin, Wei-quan
    • The Plant Pathology Journal
    • /
    • 제36권5호
    • /
    • pp.459-467
    • /
    • 2020
  • Areca palm yellow leaf (AYL) disease caused by the 16SrI group phytoplasma is a serious threat to the development of the Areca palm industry in China. The 16S rRNA gene sequence was utilized to establish a rapid and efficient detection system efficient for the 16SrI-B subgroup AYL phytoplasma in China by loop-mediated isothermal amplification (LAMP). The results showed that two sets of LAMP detection primers, 16SrDNA-2 and 16SrDNA-3, were efficient for 16SrI-B subgroup AYL phytoplasma in China, with positive results appearing under reaction conditions of 64℃ for 40 min. The lowest detection limit for the two LAMP detection assays was the same at 200 ag/μl, namely approximately 53 copies/μl of the target fragments. Phytoplasma was detected in all AYL disease samples from Baoting, Tunchang, and Wanning counties in Hainan province using the two sets of LAMP primers 16SrDNA-2 and 16SrDNA-3, whereas no phytoplasma was detected in the negative control. The LAMP method established in this study with comparatively high sensitivity and stability, provides reliable results that could be visually detected, making it suitable for application and research in rapid diagnosis of AYL disease, detection of seedlings with the pathogen and breeding of disease-resistant Areca palm varieties.

Four Year Surveillance of the Vector Hard Ticks for SFTS, Ganghwa-do, Republic of Korea

  • Kim-Jeon, Myung-Deok;Jegal, Seung;Jun, Hojong;Jung, Haneul;Park, Seo Hye;Ahn, Seong Kyu;Lee, Jinyoung;Gong, Young Woo;Joo, Kwangsig;Kwon, Mun Ju;Roh, Jong Yul;Lee, Wook-Gyo;Bahk, Young Yil;Kim, Tong-Soo
    • Parasites, Hosts and Diseases
    • /
    • 제57권6호
    • /
    • pp.691-698
    • /
    • 2019
  • The seasonal abundance of hard ticks that transmit severe fever with thrombocytopenia syndrome virus was monitored with a collection trap method every April to November during 2015-2018 and with a flagging method every July and August during 2015-2018 in Ganghwa-do (island) of Incheon Metropolitan City, Republic of Korea. This monitoring was performed in a copse, a short grass field, coniferous forest and broad-leaved forest. A total of 17,457 ticks (8,277 larvae, 4,137 nymphs, 3,389 females, and 1,654 males) of the ixodid ticks comprising 3 species (Haemaphysalis longicornis, H. flava, and Ixodes nipponensis) were collected with collection traps. Of the identified ticks, H. longicornis was the most frequently collected ticks (except larval ticks) (94.26%, 8,653/9,180 ticks (nymphs and adults)), followed by H. flava (5.71%, 524/9,180) and Ix. nipponensis (less than 0.04%, 3/9,180). The ticks collected with collecting traps were pooled and assayed for the presence of SFTS virus with negative results. In addition, for monitoring the prevalence of hard ticks, a total of 7,461 ticks (5,529 larvae, 1,272 nymphs, 469 females, and 191 males) of the ixodid ticks comprising 3 species (H. longicornis, H. flava, and Ix. nipponensis) were collected with flagging method. H. longicornis was the highest collected ticks (except larval ticks) (99.53%, 1,908/1,917 ticks (nymphs and adults)), followed by H. flava (1.15%, 22/1,917).