山形県におけるナラ枯れ被害林分での森林構造と枯死木の動態  [in Japanese] The Forest Structure and Tree Death Rate of Forest Stands Damaged by Japanese Oak Wilt in Yamagata Prefecture  [in Japanese]

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Abstract

ナラ枯れ被害を受けやすい森林特性や, 被害林再生の見込み, ナラ枯れが農山村の生活基盤に及ぼす影響を検討するため, 山形県において, ナラ林のタイプや被害程度の異なる林分の森林構造や, 被害木の分解過程などを調べた。ナラ枯れが始まってから10年内には, ほとんどのミズナラ林冠木は枯死したが, コナラ林冠木は少なくとも4割程度が生存した。激害ミズナラ林の林冠層植被率は28%だったが, 激害コナラ林では47%だった。さらに, コナラ林の亜高木層には少数ながら高木性樹種もみられた。そのため, ミズナラ林では高木層を欠く状態が長く続くが, コナラ林ではある程度の林冠修復が期待できる。しかし, 実生稚樹による天然更新は, ユキツバキを主とする常緑広葉樹が低木層を占有し続けるため, どちらのナラ林タイプでも困難だろう。また, ナラ枯れ枯死木の多くが5年ほどで倒伏したことから, 被害激化地域では, 倒木による電線切断や道路閉鎖などのライフラインの障害が数年内に頻繁に発生することが危惧される。

We evaluated forests that are vulnerable to oak wilt, and prospects of regenerating the damaged trees. Most canopies of <I>Quercus crispula</I> trees died within 10 years after the spread of the oak wilt, while the canopies of <I>Q. serrata</I> survived by approximately 40% or higher rate. The average vegetation coverage at canopy layers in a severely damaged forest was 28% in <I>Q. crispula</I> dominated stands and 47% in <I>Q. serrata</I> dominated stands. Furthermore, a small number of tree species in the sub-canopy layers of <I>Q. serrata</I> dominated stands. Thus, <I>Q. crispula</I> dominated stands are expected to lack canopy layers for many years, while canopy layers can be expected to be restored in <I>Q. serrata</I> dominated stands. However, regeneration by seedlings may not occur in either of the oak stands, because <I>Camellia japonica</I> and other evergreen broad-leaved undergrowth species will keep occupying the shrub layers. Also, since most trees that have died from oak wilt have toppled down within 5 years, the falling of dead trees may cause problems to the infrastructure, such as blocking of roads and cutting of the electric wire.

Journal

  • Journal of the Japanese Forest Society

    Journal of the Japanese Forest Society 94(5), 223-228, 2012

    THE JAPANESE FORESTRY SOCIETY

Codes

  • NII Article ID (NAID)
    130002552803
  • NII NACSIS-CAT ID (NCID)
    AA12003078
  • Text Lang
    JPN
  • Article Type
    journal article
  • ISSN
    1349-8509
  • NDL Article ID
    024071845
  • NDL Call No.
    Z18-340
  • Data Source
    NDL  J-STAGE  JASI 
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