Japanese Journal of Forest Environment
Online ISSN : 2189-6275
Print ISSN : 0388-8673
ISSN-L : 0388-8673
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Volume 57, Issue 2
Displaying 1-11 of 11 articles from this issue
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  • Effects of forest-floor alteration due to high sika deer density on soil animal communities in early summer at Oku-Nikko, central Japan
    Kazunori Tsurumi, Kei Okuda, Masaaki Koganezawa
    2015 Volume 57 Issue 2 Pages 85-91
    Published: December 25, 2015
    Released on J-STAGE: April 15, 2016
    DOIhttps://doi.org/10.18922/jjfe.57.2_85
    JOURNAL FREE ACCESS
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    We aimed to assess the effects of forest-floor alteration caused by deer on soil animals. We examined the effects of deer density on forest-floor alteration and the relationship between the composition of soil animal communities and the forestfloor conditions in 3 areas (8 plots/area) with different deer densities in Oku-Nikko, Japan. Soil compaction increased and the thickness and dry weight of the A０layer and the void index decreased significantly with an increase in deer density,suggesting that deer density contributes to forest-floor alteration. We used TWINSPAN to divide 24 plots into groups A (high deer density) and B (low deer density) and 17 soil animal groups into groups 1-4. Predaceous myriapods and mesofauna that inhabit soil voids tended to belong to groups 1-3; and they were observed mostly in group B plots. Phytophagous dipterous insects and staphylinids that showed resistance to soil disturbance tended to belong to group 4; and they were found equally in group A and group B plots. Discriminant analysis indicated that the plot classification by TWINSPAN could be interpreted according to the thickness of the A０layer and the void index. These results indicate that forest-floor alteration (decreasing in the void index and thickness of the A０layer) because of high deer density may contribute to changes in the composition of soil animal communities.
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  • Short-term impacts of logging residue at thinning on cation dynamics in Japanese cedar (Cryptomeria japonica)
    Tsuyoshi Yamada, Keizo Hirai, Chisato Takenaka, Tomohiro Nishizono, To ...
    2015 Volume 57 Issue 2 Pages 93-100
    Published: December 25, 2015
    Released on J-STAGE: April 15, 2016
    DOIhttps://doi.org/10.18922/jjfe.57.2_93
    JOURNAL FREE ACCESS
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    The promotion of over-utilization of forest biomass, especially the removal of logging residues, including the nutrient-rich foliage, at whole-tree harvesting, might influence the nutrient status of forest soils and sustainability of site productivity. To determine the short-term impact of logging residues on forest soils, we conducted thinning with and without logging residue removal (whole-tree harvesting (WTH) and stem-only harvesting (SOH), respectively). Subsequently, we investigated the changes in the dynamics of cations (Ca, Mg, and K) in the soils by using an ion-exchange resin at the WTH and SOH plots of Japanese cedar (Cryptomeria japonica) forests in northern Japan. We observed rapid decomposition of logging residues in the O horizon in SOH plot. Further, we found that K ions moved from the O horizon to the surface soil at the early stage of decomposition in the SOH plot, whereas a minor difference in the movement of Ca and Mg ions was noted at the 0- and 50-cm soil depths between the plots. Furthermore, there was no significant difference in the amounts of exchangeable cations at the surface soil (0―5-cm depth) between both the plots. Therefore, the difference of the dynamics between Ca and Mg, and K from O horizon to the surface soil was attributed to the difference in the chemical forms. In addition, the balance of exchangeable cations between the input at the 0 cm soil depth and output at the 50 cm soil depth in both the plots revealed less leaching of these cations from the 50 cm soil depth.
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  • Change of air dose rate in forests from 2011 to 2014 after the Fukushima Daiichi nuclear power plant accident
    Naohiro Imamura, Shinji Kaneko, Masahiro Kobayashi, Masamichi Takahash ...
    2015 Volume 57 Issue 2 Pages 101-107
    Published: December 25, 2015
    Released on J-STAGE: April 15, 2016
    DOIhttps://doi.org/10.18922/jjfe.57.2_101
    JOURNAL FREE ACCESS
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    In contaminated forest, it is essential to measure the temporal variation of air dose rate because forests constitute a major part of the land use in the contaminated area by Fukushima Daiichi nuclear power plant accident. In this study, we examined the temporal variation of air dose rate from 2011 to 2014 at heights 1 m and 10 cm at Japanese cedar（Cryptomeria japonica D. Don）man-made forests and the deciduous broad-leaved forest in Kawauchi-mura, Otama-mura, and Tadamimachi at Fukushima Prefecture. In addition, we examined the relationship between radioactive cesium migration from canopy to forest floor and air dose rate. From 2011 to 2012, the decrease of air dose rate was low compared with that estimated by radioactive cesium natural decay in the forests. We considered the reason why much of radioactive cesium moved from canopy to forest floor. After 2012, the air dose rate had reduced with natural decay at the forest stands, which indicated that the extent of radioactive cesium migration was very low after 2012. Therefore, we considered that the resumption due to the weathering effect was small in the forest ecosystem.
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  • Influence of forest floor cover on soil erosion risks under different site conditions and forest types
    Ryoko Hirata, Koji Kizaki, Satoshi Ito, Yasushi Mitsuda, Osamu Shimizu
    2015 Volume 57 Issue 2 Pages 109-116
    Published: December 25, 2015
    Released on J-STAGE: April 15, 2016
    DOIhttps://doi.org/10.18922/jjfe.57.2_109
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    We investigated forest floor cover (FFC) and evidences of splash and wash erosion in different stand types (hinoki plantations, sugi plantations and broadleaved secondary forests) established on various micro-topographies in order to clarify the factors affecting the surface soil erosion. Low FFCs were observed in hinoki plantations and on lower-side slopes compared to the other stand types and micro topographies, respectively. Lower FFCs were also recorded in the stands where the evidence of splash or wash erosion was observed than in the non-evident stands, indicating a relationship between FFC and surface soil erosion. Generalized linear models explaining the occurrence of splash or wash erosion demonstrated a better fitting of the model with topographic factors in addition to FFC as explanatory variables, than the null model without topographic factors. These results suggested that the stability of FFC or the effectiveness of FFC in preventing surface soil erosion could be modified by topographic factors.
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