Vegetation Recovery Process of Quercus Serrate Forest After Clear-cuttings

27 Mar Vegetation Recovery Process of Quercus Serrate Forest After Clear-cuttings

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Abstract

東京都立東大和公園において, 皆伐から回復しつつあるコナラ林の種組成と植生構造を調査した. 皆伐時期の異なる林分の間で結果を比較し, 皆伐後の植生回復過程を推定した. コナラ林を構成する樹木の種組成や, 主要な樹種であるコナラ, エゴノキ, リョウブのサイズ分布は, 皆伐後十数年を経た林と皆伐後35年以上を経た林でおおむね類似していたが, 胸高断面積合計ではなお, 前者は後者の8割弱に過ぎなかった. また, 皆伐の数年後に開始される林床管理を境にして, 樹木の種組成がリョウブ優占型からコナラ優占型へと転換していくことが示された. この結果から, 林床管理がコナラ林の回復の促進の役割を果たしているものと考えられた.

English Abstract

Quercus serrata forest is the most typical deciduous secondary forest in the Kanto district, Japan. Process of re-establishment of Q. serrata forest after a clear-cutting was studied in the Higashi-yamato Park, Tokyo Prefecture. The process was estimated based on vegetatio l surveys at seven stands that were located in Q. serrata forests in the park. At five of the seven stands, vegetation was being restored from recent clear-cuttings that were carried out in 1982, 1986, 1989, 1992 or 1994, respectively. The other two stands were set in Q. serrata forest where clear-cutti gs have not been carried out for 35 years or more. The result indicates that species composition of Q. serrata forest can almost be recovered 13 years after clear-cutting, though adequate ma gement of vegetation such as cuttings at forest floor is needed to accelerate the growth of Q. serrata. In the stands where cuttings at forest floor have not been carried out after the clear-cuttings Clethra. barbinervis was more domi nt in height and basal area than Q. serrata. It was also shown that the size distribution of Q. serrata, C. barbinervis and Stylax japonica, which are common and major component of Q. serrata forest in the Kanto district, was similar between Q. serrata forest of 13 years old and that of more than 35 years old.