Tropics
Online ISSN : 1882-5729
Print ISSN : 0917-415X
ISSN-L : 0917-415X
Volume 23 , Issue 3
Showing 1-4 articles out of 4 articles from the selected issue
ORIGINAL ARTICLES
  • Tsutomu Enoki, Keiko Yasuda, Buntarou Kusumoto
    2014 Volume 23 Issue 3 Pages 91-98
    Published: 2014
    Released: December 01, 2014
    JOURNALS FREE ACCESS
    In this study, we examined the standing aboveground biomass, biomass growth, litterfall and tree species population dynamics of mangrove forest along the Nakara River, Iriomote Island, southwestern Japan, to explain the spatial patterns of stand structure and aboveground net primary production in reference to the stand dynamics of mangrove tree species along the river. The entire aboveground biomass of the mangrove forest did not vary with topographic position at the stand level, while three mangrove species showed different distributional patterns along the river. Although Bruguiera gymnorrhiza was generally dominant, Rhizophora stylosa codominated in the downstream areas. Kandelia obovata occurred only at the river’s edge in the downstream area. The observed spatial patterns of aboveground productivity of each species depended mostly on their biomass. The distribution patterns of the mangrove tree species were based on parameters of their population dynamics, such as growth, recruitment and mortality. The effects of disturbance, especially the effects of typhoons, on the forest dynamics were prominent in this study period. The results of the study suggest that the spatial pattern of species distribution and productivity could be largely affected by the typhoon disturbances.
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  • Yoshihumi Kudo, Zaenal Mutaqien, Herwint Simbolon, Eizi Suzuki
    2014 Volume 23 Issue 3 Pages 99-110
    Published: 2014
    Released: December 01, 2014
    JOURNALS FREE ACCESS
    The increase of alien invasive plants in biological reserves is a major threat to biodiversity in tropical areas. We surveyed invasive angiosperms in two national parks in West Java and estimated their potential effects on declining biodiversity. In 2010 and 2011, we surveyed three trails in Mt. Halimun-Salak National Park (HSNP) and three trails in Mt. Gede-Pangrango National Park (GPNP). At 50-m intervals along trails from the park border to the interior, we recorded species name and coverage of invasive plants, trail width, and degree of vegetation cover of all species. Excluding members of Poaceae and Cyperaceae, 31 invasive species were found: 19 along 13.75km of trails in HSNP and 29 along 11.45km of trails in GPNP. The number of species per 500m was 10.7 in HSNP and 8.6 in GPNP. All trails in HSNP and the nearest trail in GPNP had similar species compositions. Invasive plants along these trails may have the same origin: Bogor and Jakarta. The other two trails in GPNP seemed to be affected independently by invasion from Cibodas Botanic Garden and orchards, respectively. The number of invasive species along trails was most significantly correlated with elevation, followed by distance from the park border, and trail width. The significant relationship with distance from the border highlights that a nature reserve with the same area but a longer border has a higher risk of invasion than one with a shorter border.
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  • Soontorn Khamyong, Taparat Seeloy-ounkeaw, Niwat Anongrak, Kriangsak S ...
    2014 Volume 23 Issue 3 Pages 111-125
    Published: 2014
    Released: December 01, 2014
    JOURNALS FREE ACCESS
    This study aims to evaluate the roles of community forests managed for different purposes on water storages in plants and soils as the basic information for watershed management. Community forests of Karen people in Chiang Mai province, northern Thailand, were divided to conservation (CF) and utilization (UF) forests. These community forests were classified as pine-montane and montane forests. The number of tree species in the CF and the UF was 256 and 132, respectively. Shannon-Wiener Index in the CF (4.5±0.6) was higher than in the UF (3.4±1.0). Forest biomass was higher in the CF (252.4±72.5Mg ha−1) than in the UF (139.7±36.3Mg ha−1). Water amounts contained in biomass of CF in rainy season (on August 17, 2012), winter (on December 29, 2012) and dry season (on April 20, 2013) were 208.2±68.9, 228.5±71.4 and 231.2±70.7m3 ha−1, respectively while those in the UF were 107.1±29.7, 129.0±33.3 and 124.3±33.0m3 ha−1, respectively. More than 90% of water was stored in soil. The maximum capacities of water storage within 2m soil depths of the CF and the UF were 9584 ±934 and 9463 ±233m3 ha−1, respectively. The water storage amounts in soils in rainy season were 73.8% and 79.2% of maximum capacities in the CF and the UF, respectively. In winter, the storages changed to 80.5% and 74.6%, and in dry season they decreased to be 39.5% and 23.7%. Timber harvest in the UF was the main cause of forest degradation and decrease in biomass water storage. The water storage by these community forests can reduce flash flooding and water supply from them is greatly beneficial to the villagers’ livelihood and also to the lower land communities.
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FIELD NOTE
  • Naoto Aizawa, Misa Masuda, Lauro Satoru Ito
    2014 Volume 23 Issue 3 Pages 127-134
    Published: 2014
    Released: December 01, 2014
    JOURNALS FREE ACCESS
    Aquaculture is regarded as a promising sector with its high feed efficiency and land productivity. However, capture fishery is still dominant in the northern states containing the Amazon River, where relatively late start of infrastructure development and insufficient administrative services are pointed out as the constraints. We applied snow-ball sampling in the northeast coast of Pará state and conducted interviews to nurseries and hatcheries to find current situation and the obstacles. The results of 21 privately-owned nurseries and hatcheries revealed that fishponds were constructed inside farms utilizing natural water sources; tilapia, an invasive alien species, and Serrasalmid and Pimelodid hybrids were commonly cultured; no respondents were or had been engaged in capture fishery; and aquaculture was rather regarded as a second job by farmers and stockbreeders. Distance from administrative supports favorably functioned in a sense because the aquaculturists were free from the government control. It can be expected that the water system of fishponds provides an incentive to preserve forests surrounding water sources and reservoirs.
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