丹沢堂平地区のシカによる林床植生衰退地における林床合計被覆率と土壌侵食量の関係  [in Japanese] Relationship between Forest Floor Cover Percentage and Soil Erosion Rate on the Forest Floor with an Impoverished Understory Grazed by Deer (Cervus Nippon) at Doudaira, Tanzawa Mountains.  [in Japanese]

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Abstract

神奈川県東丹沢堂平地区では, シカの採食により, 林床植生が衰退し, 土壌侵食が広い範囲にわたって進行している。土壌侵食の実態を把握するため, 堂平地区のブナ林の山腹斜面に長さ5 m, 幅2 mの土壌侵食調査プロットを17箇所設置した。これらの土壌侵食調査プロットについて, 2006∼ 2008年の3年間の4∼ 11月の期間, ほぼ毎月1回土壌侵食量を観測するとともに, 同時に撮影した写真を用いて林床合計被覆率 (林床植生被覆率+リター被覆率) を求めた。その結果, 雨量1 mm当たりの土壌侵食量 (<I>E</I>) と林床合計被覆率 (<I>F</I>) には指数関数<I>E</I>=65 exp (−0.0615×<I>F</I>) で表わされる高い負の相関があることが分かった。得られた関係式では林床合計被覆率が小さい範囲では林床合計被覆率が大きい範囲に比べて林床合計被覆率のわずかな変化が土壌侵食量に大きな影響を与えており, 既往の人工降雨実験に基づく研究により得られたリター被覆率と土壌侵食量がほぼ直線的に反比例する関係とは大きく異なる結果が得られた。

Soil erosion has been progressing over a large area on the forest floor with an understory impoverished by the feeding of deer (<I>Cervus Nippon</I>) in Doudaira (East Tanzawa of Kanagawa prefecture). Soil erosion investigation plots 5 m long by 2 m wide were set up on the hillside slope in the beech (<I>Fagus crenata</I>) forest in 17 Doudaira to monitor the amount of soil erosion. We monitored the amount of the soil erosion from 2006 to 2008 once a month from April to November. At the same time we monitored the forest floor cover percentage (the total values of understory cover percentage and litter cover percentage) by using the photographs we had taken in the same period. As a result, we have discovered that there is a strong negative correlation expressed by an exponential function (<I>E</I>=65 exp (−0.0615×<I>F</I>) ) between the amount of the soil erosion per mm of the rainfall (<I>E</I>) and the forest floor cover percentage (<I>F</I>). From the equation, a little change in the forest floor cover percentage has a bigger influence on the amount of soil erosion where the forest floor cover percentage is in the small range than when it is in the large range. This result is very different from previous studies which have shown a negative linear relationship between the amount of soil erosion and the litter cover percentage in a rainfall simulator experiment.

Journal

  • Journal of the Japanese Forest Society

    Journal of the Japanese Forest Society 92(5), 261-268, 2010

    THE JAPANESE FORESTRY SOCIETY

Cited by:  3

Codes

  • NII Article ID (NAID)
    130000420330
  • NII NACSIS-CAT ID (NCID)
    AA12003078
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    1349-8509
  • NDL Article ID
    10886999
  • NDL Source Classification
    ZR21(科学技術--農林水産--林産)
  • NDL Call No.
    Z18-340
  • Data Source
    CJPref  NDL  J-STAGE  JASI 
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