森林立地56（2），97～106 2014
Jpn J For Environ
56 (2), 97―106, 2014
和歌山県南部の人工林伐採跡地に成立した林分の構造
中森由美子1・栗 生 剛2
1和歌山県林業試験場
2和歌山県農林水産部
和歌山県南部の暖温帯域に位置するスギ・ヒノキ人工林伐採跡地において，伐採後１０～２４年を経た若齢段階の林分構造を調査し，植生タイプによる林分特性の違いを調べた。１３林分２９方形区（１０×１０m，１林分３方形区のみ５×５m）に出現した胸高直径１cm以上の木本類の調査から，林分は微地形や伐採後年数，標高の違いによって特徴付けられた４つのタイプに分類できた（陽樹・先駆種型，常緑広葉樹Ⅰ型，針葉樹型，常緑広葉樹Ⅱ型）。アラカシ， シイ類を主とした常緑広葉樹Ⅰ型は凸地形に，クスノキ，カナクギノキ，カラスザンショウを主とした陽樹・先駆種型は凹地形に分布する傾向がみられた。方形区数の多かった陽樹・先駆種型，常緑広葉樹Ⅰ型において，林分の質的な回復状況を示す非先駆性高木の幹密度，胸高断面積合計，平均樹高は量的な回復状況を示す林分の胸高断面積合計が増加するほど増加した。一方，伐採後年数の増加による非先駆性高木の幹密度，胸高断面積合計の増加は みられなかった。陽樹・先駆種型および常緑広葉樹Ⅰ型の植生回復は，伐採後の経過時間によって植生回復の度合 いが一律に決まるのではなく，一定量の樹木の定着・成長が見込めれば量的に回復するという点で類似していた。 伐採後１０～２４年経過した林分において，常緑広葉樹Ⅰ型および陽樹・先駆種型は樹種の違いを除けば，非先駆性高木の定着量などの林分構造に大きな違いはないと考えられた。
キーワード：皆伐，天然更新，二次遷移，先駆種，常緑広葉樹
Yumiko Nakamori, Tsuyoshi Kuriu：Stand structure
after clear-cutting of coniferous plantations in
southern
Wakayama Prefecture, Japan. Japanese Journal of Forest Environment 56:97―106, 2014.
We investigated the stand structure
of plantation sites clear-cut
10-24 years ago in the warm-temperate zone of southern Wakayama Prefecture, Japan. We examined differences in stand characteristics among vegetation types. In the study stands
(29 study plots, mainly 10 × 10 m), the mean stem density of trees more than 1 cm in diameter at breast height were censused. Stands were classified into four types characterized by differences in micro-topography, the number of years after harvesting, and altitude: shade-intolerant and
pioneer type, evergreen
broad-leaved type I, conifer type, and evergreen broad-leaved type II. Evergreen broad-leaved type I (dominated by Quercus glauca and Castanopsis species) were distributed across convex topography, whereas shade-intolerant and pioneer type (mainly consisting of Cinnamomum camphora, Lindera erythrocarpa, and Zanthoxylum ailanthoides) were distributed within concave topography. In shade-intolerant and pioneer type and evergreen broad-leaved type I, the stem density, basal area and mean height of non-pioneer trees, which are
indicators of qualitative recovery in the vegetation, increased with increasing stand basal area, which are indicators of quantitative development in the vegetation. However, the stem density and basal area of non-pioneer
trees did not increase with
increasing the number of years after cutting.
These results indicate that recoveries of these two vegetation types were similar; when sufficient numbers of trees became established and grew, the vegetation recovery appeared to progress. In the study sites,the two vegetation types seemed to have similar stand structure in terms of the amount of non-pioneer trees, except the difference in individual tree species.
Key words : Clear-cutting, evergreen broad-leaved tree, natural regeneration, pioneer species, secondary succession