Tropics
Online ISSN : 1882-5729
Print ISSN : 0917-415X
ISSN-L : 0917-415X
Volume 13, Issue 4
Displaying 1-5 of 5 articles from this issue
Regular papers
  • Ahmad Jailani Muhamed YUNUS, Nobukazu NAKAGOSHI, Ab Latif IBRAHIM
    2004 Volume 13 Issue 4 Pages 235-248
    Published: 2004
    Released on J-STAGE: October 31, 2008
    JOURNAL FREE ACCESS
    This study was conducted to develop appropriate mapping and assessment techniques to quantify the nature and magnitude of riparian landscape structural changes along the Pinang River using remote sending data. Based on stream order land-use ranks classification, the stream ecosystem health can be determined. The lower rank stream order segment indicates that, the stream ecosystem is in good condition. Vegetation land-use changes from 1992 to 2000, within fixed 50-m width stream buffer, were identified using GIS and used to estimate the riparian zone and subsequently calculate the landscape patterns using Patch Analyst. Since the Pinang River watershed is the most urbanized, it experienced rapid development and land-use changes that deteriorated the watershed ecosystem. The riparian land-use patterns in 1992 and 2000 were studied by landscape metrics such as areal percentage, patch number per unit area, landscape diversity, evenness index, and mean fractal dimension. The results show that in vegetation areas have significantly decreased mainly due to conversion to urban and built-up, agricultural, and recreational land. Thus, riparian vegetation corridors have become more fragmented, isolated, and much smaller. The large proportion of deforested riparian areas within stream order segments raises serious questions about the watershed ecosystems health and the longer term possibility of river degradation by upland clearing. Furthermore, most of the agricultural land is being displaced to the hill slopes and hilly area (85% of first-order stream located), while urban and built-up developments are gradually replacing the original agricultural land. Based on landscape metrics, it has been revealed that landscape metrics indices are significant for evaluating the riparian land-use and land cover change, in addition integration of GIS and remote sensing to quantify landscape structure is a feasible and efficient way to evaluate the temporal effect of land-use activities on watersheds.
    Download PDF (550K)
  • Sasitorn POUNGPARN, Akira KOMIYAMA, Pipat PATANAPONPAIBOON, Chatree MA ...
    2004 Volume 13 Issue 4 Pages 249-253
    Published: 2004
    Released on J-STAGE: October 31, 2008
    JOURNAL FREE ACCESS
    The whole root system of a Sonneratia caseolaris tree of the edge of a secondary mangrove forest was carefully excavated using a water-pump. All roots were sorted by diameter and weighed. The root-weight distribution showed that the medium (10-20 mm) and large (20-30 mm) classes shared a large portion of root weight. We analyzed the relationship between the root diameter (D) and the number of roots (F’). A significant inverse linear relationship was obtained for the F’-D relationship. The slope was not statistically different from -2.0, suggesting that the root system of this S. caseolaris tree follows the pipe model (Shinozaki et al., 1964a, b). The constant between total root weight (WR) and the square of the stem diameter at ground level (D0) was calculated. This proportional constant of S. caseolaris (0.025) was lower than that of X. granatum (0.051), which was formerly clarified to obey the pipe model theory (Poungparn et al., 2002). We discussed the application of the pipe model theory to estimate the root weight of mangroves from the WR-D02 relationship’s constant.
    Download PDF (117K)
  • Laode ALHAMD, Akio HAGIHARA
    2004 Volume 13 Issue 4 Pages 255-268
    Published: 2004
    Released on J-STAGE: October 31, 2008
    JOURNAL FREE ACCESS
    The seasonal patterns of litterfalls, such as leaves, woody organs, reproductive parts, insect bodies, and feces, were investigated monthly for three years from January 1999 to December 2001 in a subtropical evergreen broad-leaved forest in the northern part of Okinawa Island, Japan. The total annual litterfall was estimated at 6.66-8.28 Mg ha-1 yr-1. The litterfall was mainly composed of leaves (52.4- 54.8% of the total litterfall), about half of which were from Castanopsis Sieboldii. The species composition of leaf litter was almost consistently the same every month for a year. The leaf litter was separated into two groups: one group, which had a high proportion of the total leaf litter, included C. Sieboldii, Schima Wallichii, Elaeocarpus japonicus, and Cinnamomum Doederleinii; the other group included the other 44 species. The species diversity indexes of leaf litter H’ and J’ showed their minimum values in March, when the leaf litter reached its maximum. There was no significant difference in species rank among years in terms of the annual amount of leaf litter. The mean leaf litter per tree of a given species was significantly proportional to its corresponding basal area, regardless of species and year. The degree of overlap in the seasonal patterns of litterfall components showed that leaves, insect bodies, and reproductive parts are nearly overlapped, but woody organs and feces are more or less exclusive to the other three components. Although the seasonal patterns in leaf litter of C. Sieboldii, S. Wallichii, and E. japonicus were nearly overlapped, the seasonal pattern in leaf litter of C. Doederleinii was almost independent of those of the other three species.
    Download PDF (243K)
  • Masahiro ICHIKAWA
    2004 Volume 13 Issue 4 Pages 269-286
    Published: 2004
    Released on J-STAGE: October 31, 2008
    JOURNAL FREE ACCESS
    Previous research has dealt with the relationships between forests and the people living in and around forests practicing swidden farming, in tropical rain forest climates in insular Southeast Asia. It was pointed out that hill swidden farming with a long enough fallow period has been considered to be in harmony with the forest environment. However, there have been few studies on the relationships between forests, and resource use and agriculture as a whole. This paper, as a result of a case study in an Iban village in Sarawak, demonstrates that the Iban allow all their agricultural lands (swamp paddy fields, Para rubber gardens, fruit gardens, pepper gardens, and, of course, hill swiddens) to return to natural forests, or construct man-made forests that are similar to natural forests. In addition, considering other activities such as fishing, hunting and collection of forest products, it can be seen that the resource use and agriculture practices of the Iban are based on secondary forests.
    In resource use and agriculture, the natural, social and economic environments play important roles. One important natural factor is strong vegetation recovery. As the villagers recognized, when forests recover, thick weeds on agricultural lands disappear and the fertility and structure of soils are improved. After the return to secondary forest with a strong recovery of vegetation, agricultural land is opened again. The villagers benefit with less labor and capital, as tillage work and fertilizer application are not necessary. Large fluctuations in social and economic conditions outside the village affected the villagers’ attitudes toward resource use and agriculture. Within this setting, the Iban in Nakat have survived by rapidly changing activities regarding resource use and agriculture, adapting to the social and economic conditions of their surroundings. For the Iban, secondary forests have a high potential value. The secondary forests house plants and animals that are current and potential resources. These forests can also be easily converted to other kinds of agricultural use at a low cost. These are the reasons for the Iban’s secondary forest based resource use and agriculture.
    Download PDF (1000K)
Field Note
  • Hongwei TAN
    2004 Volume 13 Issue 4 Pages 287-291
    Published: 2004
    Released on J-STAGE: October 31, 2008
    JOURNAL FREE ACCESS
    Guangxi province is located in the southern sub-tropical region of China has high temperatures and heavy rainfall, resulting in soils with mainly low cation exchange capacity (CEC), low organic matter, and poor phosphorus (P), potassium (K) and sulphur (S) nutrient content (Zhang et al., 1998). According to the results of 86 trials in Guangxi, application of potassium (K) fertilizer significantly increased yield more than the application of NP fertilizer only, and also increased the quality of crops and fruit markedly. As lateritic red soil, latosol and silicosol in upland soils of Guangxi contain a low amount of exchangeable magnesium of less than 70 mg⁄kg, Mg application also improved crop growth.
    The major lowland cropping system is early rice-late rice. Over the years, less and less organic matter has been recycled (Yoshida,1981), because it has been put to commercially as fodder, or fuel. At the same time, for P calcium-magnesium-phosphate (CaMgP) use has increased. With increasing yields, the uptake of S by rice also increased (Morris, 1990). Thus, S deficiency started to become a serious problem.
    When K fertilizer was applied to crops, gross income increased between 1,871-4,634 RMB⁄ha. For fruit trees, applying K fertilizer increased gross incomes 4,424-25,043 RMB⁄ha. The benefits from the application of S-fertilizers, rice-rice cropping system, Ammonium sulphate, Single superphosphate, Elemental S and Gypsum resulted in a net income of 1891.9 RMB⁄ha, 1821.3 RMB⁄ha, 1883.0 RMB⁄ha and 1659.0 RMB⁄ha, respectively.
    Download PDF (117K)
feedback
Top