Japanese Journal of Forest Environment
Online ISSN : 2189-6275
Print ISSN : 0388-8673
ISSN-L : 0388-8673
Volume 50, Issue 2
Displaying 1-9 of 9 articles from this issue
  • Kikuo Haibara, Hiroto Toda, Rieko Urakawa
    Article type: Comment
    2008 Volume 50 Issue 2 Pages 97-109
    Published: December 25, 2008
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS
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  • Hideaki Shibata
    Article type: Record
    2008 Volume 50 Issue 2 Pages 111-116
    Published: December 25, 2008
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS
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  • Naoshi Watanabe, Hidehisa Fukata, Jiro Tsukamoto
    Article type: Article
    2008 Volume 50 Issue 2 Pages 117-123
    Published: December 25, 2008
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS
    In order to elucidate the causal relationship between heavy thinning and resin flow on the trunks of remaining Hinoki cypress (Chamaecyparis obtusa) trees without any external signs of physical or insect damage and fungal infection, relation between the resin flow and thinning rate and site conditions was studied in 35 Hinoki cypress stands from 11 districts of Kochi Prefecture. In addition, traumatic resin canal formed in secondary phloem under the starting point of resin flow was observed microscopically with 5 sample trees from two studied stands. Larval tunnels and/or feces of insects were also checked with the same samples. One or two tangential lines of traumatic resin canals were found in all the samples which differed from the many lines of traumatic resin canals characteristic of the "Rooshi resinous canker". Traces of insects were not found in inside as well as outside of the bark. Thus, the cause of the resin flow observed in the suited stands was considered not to be fungal infection and insect damage. The resin flow was not found in most of the control stands without thinning. Ratio of number of trees with resin flow to the total number of trees (RRF) increased with increasing rate of thinning. Number of the spots of the resin flow on individual trees also increased as thinning rate increased. RRF was lower in those stands on north-facing slopes and/or at altitudes of more than 1,000m than elsewhere. Number of the spots of the resin flow was fewer on the northern hemicycle than on the southern one of tree trunks. Based on these findings, it was concluded that the resin flow is a response of Hinoki cypress trees to some kind of environmental stress caused by heavy thinning and the level of the resin flow rises with the increase in the stress and varies with site conditions.
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  • Kazuhiko Masaka, Kenji Yamada
    Article type: Article
    2008 Volume 50 Issue 2 Pages 125-132
    Published: December 25, 2008
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS
    The occurrence of native plant species in nine artificial Robinia pseudoacacia L. stands (34 yrs.-94 yrs.) was evaluated in Sorachi and Ishikari regions, central Hokkaido. In the stands, total 27 tree species were found, and the maximal dbh increased with increasing stand age. The relationship between maximal dbh and stand age of native tree species did not differ significantly with that of R. pseudoacacia suggesting that the native trees invaded into the stands at the earlier stage and grew with R. pseudoacacia. On the other hand, total 43 plant species were observed on the forest floor, and the number of plant species increased significantly with increasing stand age. The number of plant species increased significantly with decreasing degree of coverage of dwarf bamboo. The degree of coverage of dwarf bamboo was significantly correlated with sum of basal area at stand level. These results imply that cover of dwarf bamboo would decline with stand growth, and the situation might allow other plant species to invade into and establish in R. pseudoacacia stands.
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  • Haruko Ochi, Hiromasa Koyama, Norio Takahashi
    Article type: Article
    2008 Volume 50 Issue 2 Pages 133-139
    Published: December 25, 2008
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS
    Japanese wing nut (Pterocarya rhoifolia) showed about eighteen times variation in seed mass within a species. In this study, we have especially focused on the proximal factors generating the seed size variation within an infructescence. Seeds at proximal end of infructescence were generally greater in mass than those of distal end. Since flowering time among florets at different positions on inflorescence (proximal, intermediate, distal end, respectively) did not differ on another, it could be concluded that flowering phenology did not affect seed size variation. However, sizes of florets were significantly larger at proximal end than those of distal end. Moreover, flower-removal treatment resulted in enhancing the size of intermediate and distal seeds derived from remaining florets. But the sizes of seeds at proximal end did not differ from control. Therefore, it did not reveal that whether the resource competition among the seeds on an inflorescence for maternal resources was the sources of seed size variation. This study showed that the sources of seed size variation in Japanese wing nut are the initial floret size among different position on the inflorescence.
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  • Arifin Abdu, Sota Tanaka, Shamshuddin Jusop, Nik Muhamad Majid, Zahari ...
    Article type: Article
    2008 Volume 50 Issue 2 Pages 141-152
    Published: December 25, 2008
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS
    The rehabilitation of degraded tropical rainforest was studied in the Chikus Forest Reserve, Perak, Peninsular Malaysia. Growth performance and soil fertility status were assessed for two indigenous dipterocarp species, Shorea leprosula and S. parvifolia planted under a secondary forest in 1994 and under an abandoned Acacia mangium plantation in 1992 with a multi-storied plantation technique. The assessment was conducted with a special reference to two indices; soil fertility index (SFI) and soil evaluation factor (SEF), which are commonly used for soil fertility assessment in relation to the succession of secondary forests in humid tropical regions. The results showed that among various inter-spacing planting, moderate planting spacing of 20 m in the secondary forest and 15 m in A. mangium plantation resulted in most favorable growth of both species. The significant correlation between SFI and growth performance suggested that the applicability of the SFI as an index for estimating soil fertility and site quality for rehabilitation of degraded forestland with a multi-storied plantation technique. However, any correlation was not found with the SEF. It is concluded that, the soil fertility status evaluated by the SFI can play an important role for determining the growth of planted dipterocarp snecies.
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  • Yoshimi Sakai, Masamichi Takahashi, Shigehiro Ishizuka, Yoshiyuki Inag ...
    Article type: Article
    2008 Volume 50 Issue 2 Pages 153-165
    Published: December 25, 2008
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS
    Decay rates of dead wood after non-commercial thinning, i.e., fallen logs, stumps, and snags, in plantation forests were estimated from changes in wood density over time. Decay rates were compared using the decay constant k of the exponential function (D = a exp (-kt), where D : wood density, a : a constant, t : time, k : decay constant). The plots examined were in 15 prefectures from the north to the south of Japan, and contained five dominant planted species : Cryptomeria japonica, Chamaecyparis obtusa, Larix kaempferi, Picea glehnii, and Abies sachalinensis. Decay rates of fallen logs and stumps were estimated separately for two diameter classes : 5-15cm and 15-40cm. The decay rates of P. glehnii, A. sachalinensis, and L. kaempferi, which are planted in relatively cool regions, were slower than those of C. japonica and C. obtusa. No significant difference in decay rates was found between C. japonica and C. obtusa planted in a similar climate range. The decay rates of snags were very slow, followed by stumps and fallen logs. The decay rates of fallen logs with a diameter of 5-15cm had a significant positive relationship with cumulative temperature and actual evapotranspiration, suggesting that smaller-diameter fallen logs decay faster in warmer, humid regions. However, no clear relationships between decay rates and climate conditions were found in fallen logs of 15-40cm diameter or in stumps, but very slow decay rates were found in cool regions.
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  • Asami Nakanishi, Yoshiyuki Inagaki, Hidehisa Fukata, Shozo Shibata, Na ...
    Article type: Article
    2008 Volume 50 Issue 2 Pages 167-173
    Published: December 25, 2008
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS
    Pollen of hinoki cypress (Chamaecyparis obtusa Endlicher) causes allergy and forest management reducing male flower production is required. Effects of soil properties and high intensity thinning on male flower production in hinoki cypress were evaluated. Six forests were selected having different soil properties and site characteristics in Kyoto and Kochi prefecture. Within each forest two study plots were selected; one plot was thinned with strong intensity (>50%) and the other was not thinned or thinned with ordinary intensity (<25%) as the control plot. Male flower production of hinoki cypress was measured over 3 years from 2005 to 2007. Male flower production was not different between the Kyoto and Kochi sites although the climatic condition was very different. Male flower production was higher in 2005 than the other two years in most plots. Male flower production of a mast flowering year in 2005 was higher where soil CN ratio was lower. By contrast, there was no significant relationship between male flower production and soil CN ratio in 2006-7. There was no significant difference in male flower production between control plots and high intensity thinning plots. Male flower production per unit area would not decrease after strong thinning in spite of reduction in tree numbers, because male flowers per individual tree located in or adjacent to high intensity thinning plots increased substantially. The results suggest that high intensity thinning is not a useful management practice reducing male flower production and that male flower production of hinoki cypress is higher where soil nutrient availability is higher in a mast flowering year.
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  • Takahiro Ichikawa, Asuka Ichikawa, Rieko Urakawa
    Article type: Report
    2008 Volume 50 Issue 2 Pages 175-177
    Published: December 25, 2008
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS
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