学術雑誌論文 <論文・報告>森林管理が土壌微生物の分解機能の多様性に及ぼす影響

Ninomiya, Ayumi  ,  Yamamoto, Touya  ,  Mukai, Mana  ,  Tsujii, Yuki  ,  Yokoyama, Daiki  ,  Kitayama, Kanehiro

2pp.87 - 90 , 2017-03 , 京都大学学際融合教育研究推進センター高大接続科学教育ユニット
内容記述
本研究では,人間の管理によって変化した樹木種の多様性が,土壌微生物の分解機能の空間的多様性にどのような影響を与えるのかについて,京都周辺の3つの森林(常緑広葉樹林,里山林,ヒノキ林)を比較して評価した.各森林から表層土壌を一定間隔で10コア採取し,コア毎に土壌懸濁液を作成し,31種類の有機物が基質として含まれるエコプレートに添加して25度で96時間培養し,土壌微生物による基質の分解度を吸光度を用いて測定した.得られた30コア×31有機物分解度のマトリクス・データに,主成分分析を適用して,コア間の分解機能のばらつきを評価した.樹木種多様性は,常緑広葉樹林>里山林>ヒノキ林の順に低下した.主成分分析の結果,常緑広葉樹林と里山林に比べて,単一樹種のヒノキ林では分解機能のコア間のばらつきが有意に小さかった.以上の結果は,樹木種多様性の著しい低下が土壌微生物の分解機能の空間的多様性の低下を引き起こすことを示唆した.森林の生物多様性を守るために,森林管理を行う際には地上部の多様性のみならず,地下部の多様性にも目を向ける必要がある. In this study, we investigated if/how reduced tree-species diversity due to human interference affects the spatial variability of soil microbial activities by comparing three forest types, which commonly occur in Kyoto (i.e. evergreen broad-leaved forest, satoyama forest, and hinoki-cypress plantation). We collected ten soil cores from the topsoil at regular intervals in each forest. Soils from each core were diluted 100 times in extracting solution and suspended solids were inoculated to a piece of the Biolog EcoPlate, which contains 31 types of organic compounds for microbial community profiling. Inoculated EcoPlates were incubated at 25°C for 96 hrs. Decomposability of each organic compound was assayed by reading spectral absorbance. A principal component analysis (PCA) was applied to the derived data matrix consisting of 30 cores and 31 compounds. Tree species richness decreased in the order of evergreen broad-leaved forest > satoyama forest > hinoki plantation. Results of PCA indicated that the variability among cores was significantly reduced in the hinoki forest than in the other two forests. This suggests that the spatial variability of soil microbial communities/activities is significantly reduced under the mono-specific canopy of the hinoki forest. Because soil microbial communities are an important aspect of biodiversity in a forest ecosystem, microbial diversity needs to be taken into account for better managing those forests.
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http://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/224840/1/ELCAS_J_2_87.PDF

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