Tropics
Online ISSN : 1882-5729
Print ISSN : 0917-415X
ISSN-L : 0917-415X
Volume 2, Issue 1
Displaying 1-5 of 5 articles from this issue
  • Erizal MUKHTAR, Eizi SUZUKI, Takashi KOHYAMA, Marlis RAHMAN
    1992 Volume 2 Issue 1 Pages 1-12
    Published: 1992
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    All individuals of Calophyllum cf. soulattri Burm. (Guttiferae) were surveyed in two plots set in a tropical rain forest, Padang, West Sumatra. In Pin plot (1.0 ha) covered mostly by mature patch of 50-60 m in height, we found four mother trees of C. cf. soulattri (27-39 m in height), and 2,722 juveniles (0-9 m). Instead of the seedling abundance, the mother trees made fruits only in 1981 during the survey period from 1981 to 1989. They seemed to disperse fruits in the whole area of plot. The seedlings and saplings in a subplot of 14 m2 adjacent to a mother tree, 30-38% of them survived from 1981 to 1989 and grew 2.5 cm/yr in height. Bigger juveniles (4-9 m) occurred more often in area apart from mother trees. In Gaja plot (0.86 ha) having more gaps than Pin Plot, only 31 C. cf. soulattri existed, which were 0.7-17 m in height.
    The following regeneration characteristics are supposed for this species. 1) Only old and big tree can reproduce, and the dispersal area of propagule is wide; 2) the dispersed propagule can survive around the mother trees; 3) the residual life span after maturation is short, and die before offsprings start reproduction. These characteristics will make a mosaic of two types of patches: one composed of mother tree, seedlings and saplings, and the other of young poles. The patch size will be related to dispersal area. Thus the plant population exists continuously in the same area, while sporadic reproduction events create the mosaic pattern.
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  • Vipak JINTANA, Ikuo NINOMIYA, Kazuhiko OGINO
    1992 Volume 2 Issue 1 Pages 13-22
    Published: 1992
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    The root development of Rhizophora apiculata seedling under extremely low oxygen of the soil was contrasted with that under normal concentration. A young seedling grown in a pot of 10.7 cm in diameter and 42 cm in height was treated either unaerated or aerated condition in greenhouse. Each pot was flooded with Hoagland’s nutrient solution to the upper tip. The oxygen concentration of the soil at 15 cm depth was found to have kept at the level below 0.6 mg l-1 under unaerated, between 2.2 and 2.5 mg l-1 under aerated treatment. The seedlings were sampled after 85 and 115 days of treatments to examine root length, number of the main and lateral root, and dry weight. It was disclosed that biomass, vertical distribution and elongation rate of the root remarkably decreased, and number of lateral root sharply increased. Although, T/R ratio showed no difference between the treatments, the proportion of fine roots increased. Intercellular space in the root cortex was found also increasing. It was concluded that the lower oxygen concentration of the soil caused the morphological and anatomical deformation of the R. apiculata seedlings.
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  • Ken OYAMA, Rodolfo DIRZO, Guillermo IBARRA-MANRIQUEZ
    1992 Volume 2 Issue 1 Pages 23-28
    Published: 1992
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    Population structure was analyzed for five of the most common species of palms, Astrocaryum mexicanum, Bactris tricophylla, Chamaedorea oblongata, C. tepejilote and Geonoma oxycarpa in a Mexican lowland rain forest. Height and cover of palms with a height> 1.5 m were measured in three 600 m2 plots. The most common species in terms of density were C. tepejilote and A. mexicanum. The highest accumulated cover corresponded to A. mexicanum.Taller palms of C. tepejilote showed higher cover. Almost all palm species had the same architectural model (Comer) and B. tricophylla had the Tomlinson model. Richness of palm species was low compared to other tropical forests although the understory palms in this community represent more than 50 % of all the individuals of the understory vegetation at Los Tuxtlas. The genus Chamaedorea was the most diversified (5 species) while the other genera had only one species.
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  • Haruo FUKUHARA, Gerald Eustaquio TORRES, Sonia Maria CLARO MONTEIRO
    1992 Volume 2 Issue 1 Pages 29-34
    Published: 1992
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    Diurnal and diel emergence patterns of Chaoborus (Edwardsops) magnificus were investigated in a dry season, using two emergence traps set in the center of Lake Dom Helvecio, Southeastern Brazil. This species showed the highest catches up to 95 % of total ones including four Chaoborus species during about one month. It initiated to emerge largely at new moon night. Emergence of this species occurred actively between 3:00 am. and 6:00 am., namely before sunrise. The synchronization of growth of this species under lunar cycle is strongly suggested. The meaning of synchronization in emergence of chaoborids is discussed.
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  • Oddy A. MANUS, Eddy MANTJORO, Yoshito JINNOUCHI, Yukio SHIGEMI
    1992 Volume 2 Issue 1 Pages 35-48
    Published: 1992
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    A study of fishing household economy in rural Indonesia with particular reference to Kematiga, North Sulawesi was performed. The economy of the village is mainly supported by fisheries. The dominant marine fishing gear are angling, gill netting, and purse seine fisheries. In order to analyze the economics of fishing households, they were divided into four classes: a) fishing laborers’ households (FLH); b) angling fishing operators’ households (angling FOH); c) gill netting FOH; and d) purse seine fishing Fan.
    The capital formation by the FOH was made through self-made, savings, and loans. In fisheries investment, which reflects the scale of each fishing activity, angling fishery had the lowest amount, gill netting was in the middle, and the purse seine fishery was significantly higher. With regards to income and expenditure, the amounts for the FOH were significantly higher than those for the FLH. Among FOH, those of purse seine fishery were definitely greater than those of gill netting and angling. However, the FLH’s expenditures often exceeded their incomes. As a result, they usually had to borrow money from FOH, or receive gifts from the richer families based on the traditional mutual aid system in the village.
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