森林立地学会誌 森林立地 51(1)，2009，69〜76
Jpn．J．For．Environment 51(1)，69-76
2009
多雪地帯のスギ人工林皆伐跡地において標高の違いが
木本種の定着に与える影響
小谷二郎１
１石川県林業試験場
日本海側の多雪地帯の異なる標高域で，スギ人工林の皆伐跡地（0.33〜1.87 ha）で再生した木本種の種数，立木密度および種構成を隣接スギ人工林および周辺広葉樹林と比較した。種数および立木密度は，高標高域の一部を除いてスギ人工林およびその皆伐地でよりも広葉樹林で多くなる傾向があった。低標高域の皆伐地では，いくつかの埋土種子由来の樹種が高密度でしかも高頻度に出現した。一方，高標高域では皆伐地で種数や立木密度は減少する傾向があったものの，広葉樹林に共通した樹種がスギ人工林に多く出現した。高標高域のスギ人工林は，豪雪よって若齢時から成林阻害を受けている。それによって，人工林内で更新しやすい光環境が創られていると考えられた。種子散布型からみた種数は，スギ人工林ではどの散布型も標高とともに増加する傾向にあった。しかしながら，皆伐地では低標高域ほど被食散布型に偏り，高標高域ではスギ人工林に比べて被食散布型および風散布型が減少した。前生稚樹を生かした速やかな植生回復のためには高標高域の方が有利と考えられるが，攪乱強度の弱い伐採や集材方法を選択することでさらに多様な種構成を維持できると考えられた。
キーワード：標高の違い，皆伐跡地，植生回復，スギ人工林，多雪地帯
Jiro Kodani：Effect of
elevation on establishment of woody species at clear-cut sites of Cryptomeria japonica plantations at different elevations
in heavy snow regions. Japanese Journal of Forest Environment 51:69−76, 2009.
Richness, stem density and composition of woody species
were compared among the clear-cut sites（0.33-1.78 ha）and adjacent sites（non-clear-cut site）of Cryptomeria
japonica plantations, and
surrounding broad-leaved forests at different elevations in heavy snow regions,
on the Japan Sea side of central Japan. The richness and stem density of woody
species tended to be higher in the surrounding broad-leaved stands than at the
non-clear-cut sites or the clear-cut sites of plantations, except for some
cases at a higher elevation. Some species originating from buried seeds
occurred densely and frequently at the clear-cut sites at a low elevation. On
the other hand, many woody species at the non-clear-cut sites were the same as
those in broad-leaved forests at a higher elevation, although the frequency or
density of these species tended to decrease at the clear-cut sites. The growth
of C. japonica planted at a higher elevation is suppressed by heavy snow
during the young seedling stage. This provides a favorable light condition for
the advanced regeneration of woody species at the non-clear-cut sites. Species
richness at the non-clear-cut sites tended to increase with the rise of
elevation in all seed-dispersal types. Species richness of the clear-cut sites
at a lower elevation, however, showed a tendency toward the frugivore-dispersed
type and, that of the frugivore- and wind-dispersed types at a higher elevation
is less at the clear-cut than at the non-clear-cut sites. Vegetation recovery
at the clear-cut sites by advanced regeneration of seedlings may be clearer at
a higher elevation than at a lower elevation, but moderate cutting or logging
methods at plantations may be useful for rapid recovery of various species.
Key words：Clear-cut site, Cryptomeria japonica plantation, Different elevation,
Heavy snow region, Vegetation recovery