森林立地学会誌 森林立地35(1), 1993, pp. 32〜41
論 文
structure
and dynamics of an old-growth
Chamaecyparis forest in the Akasawa Forest Reserve,
Kiso
district, central Japan
Shin-Ichi YAMAMOTO
山本進一：木曽赤沢自然休養林におけるヒノキ属老齢林の構造と動態
長野県木曽郡上松町にある赤沢自然休養林内の、ヒノキ単純林分（１林分）、アスナロを混交したヒノキ優占林分（２林分）、ヒノキと広葉樹を混交したサワラ林分（１林分）の合計４林分においてヒノキ属老齢林の構造と動態について調査した。林冠木（胸高直径20cm以上）の胸高直径分布はヒノキ林分のヒノキでは50−60cmにモードを持ったのに対して、サワラ林分のサワラはL字型を示した。根上がり状態の林冠木がヒノキで観察された。ヒノキ単純林分の下層は低木性広葉樹で優占されていた。一方、アスナロを混交したヒノキ優占林分の下層はアスナロ下層木で優占されていた。ヒノキ林分ではヒノキ下層木が見られなかった。サワラ林分の下層ではサワラ下層木が優占し、ヒノキ下層木も出現した。1985年から1990年までの5年間で、ヒノキ林分のみで林冠木が枯死し、枯死率は1−３%であったが、サワラ林分では林冠木が枯死しなかった。林冠木の年平均直径生長は0.3−1.2cmの範囲であった。同期間中の下層木の枯死率は8−23%で、その内訳はサワラが11.1%、アスナロが12−21%であったが、ヒノキ下層木は枯死しなかった。
Structure and dynamics
of an old-grewth Chamaecyparis forest
in the Akasawa Forest Reserve, Kiso district, central Japan, were investgated
in four stands with different species composition in the canopy: a pure C. obtusa stand, twe stands dominated by
C. obtusa with a few Thujopsis
dolabrata, and a stand dominated by C.
pisifera mixed with C. obtusa and hardwoods. C. obtusa had its dominate dbh class
around 50-60cm in the C. obtusa
sutands, but the distribution of C.
pisifera showed an L-shape in the C.
pisifera stand.Stiltrooted canopy trees of C. obtusa were found. The understory layer of the pure C. obutusa stand was dominated by small
trees or shrubs of hardwood species, and that of stands with C. obtusa and T. dolavrata in the canopy was dominated by T. dolabrata saplings. There were no saplings of C. obtusa in stands in which it was a
canopy dominant. C. pisifera saplings
dominated and few C. obtusa saplings
occurred in the understory layer of the C.
pisifera stand. For five years during 1985-1990, mortality of canopy trees occurred
only in the C. obtusa stands; the
rate was one to three percent. Mortality was absent in the C. pisifera stand. Mean annual dbh growth of canopy trees ranged
0.3-1.2cm. Mortality rate of stems in the understory layer of each stand ranged
8-23% during this period. The rate was 11.1% for C. pisifera and 12-21%
for T. dolabrata, but there was no
mortality for C. obtusa saplings.