A preliminary investigation on the effects of thinning on biomass of understory vegetation and floor cover percentage in Japanese cedar plantations

Ide Junichiro, Sun Haotian, Okabe Norikazu, Jeong Shengxun, Otsuki Kyoichi

doi:10.15017/1654302

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スギ人工林における間伐が下層植生の現存量と林床の被覆状態に及ぼす影響について
スギジンコウリンニオケルカンバツガカソウショクセイノゲンソンリョウトリンショウノヒフクジョウタイニオヨボスエイキョウニツイテ

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Abstract

The effects of thinning on the biomass of understory vegetation and the floor cover percentage (FCP) were investigated in the coniferous plantation watersheds composed of Japanese cedar in the lower slope and Japanese cypress in the upper slope in Yayama district, Iizuka, Japan in 2015. The research sites were set at the valleys of adjacent two thinned watersheds and one non-thinned watershed. Selective thinning of 35% and 50% in number was conducted in the thinned watersheds during January to March in 2012. Fresh and dry weights of understory vegetation increased with increasing rate of thinning in the test sections covered by Japanese cedar. Additionally, the height of understory vegetation sampled in the thinned sections was mostly below 50 cm and 86 cm at a maximum. These results suggest that an increase in aboveground biomass of low-height understory vegetation is attributable to the improvement of light environment under forest canopy by thinning. The FCP was high in the all sections (89%-100%) whereas the percentage of each floor element to the forest floor was different among the sections. Our results indicated that understory vegetation and litter mainly contributed to the high FCPs in the thinned and non-thinned sections, respectively.

Journal

九州大学農学部演習林報告

九州大学農学部演習林報告 97 11-16, 2016-03-30

The Kyushu University Forests

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