Effects of mitigation of competition in rhizosphere between tree and understory vegetation on nitrogen dynamics and tree growth through mycorrhiza

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K07830
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Forest science
• Research Institution: Hokkaido University
• Principal Investigator: FUKUZAWA Karibu 北海道大学, 北方生物圏フィールド科学センター, 准教授 (10456824)
• Co-Investigator(Kenkyū-buntansha): 谷口 武士 鳥取大学, 乾燥地研究センター, 准教授 (10524275)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 土壌窒素 / ササ / ミズナラ / 細根 / 純一次生産 / 外生菌根菌 / 土壌環境 / 食害

Outline of Final Research Achievements

We manipulated removal of a dominant understory vegetation, Sasa senanensis in cool-temperate forests in Japan, and investigated the effect of the removal on soil nitrogen dynamics, fine root dynamics, net primary productivity of the trees, mycorrhizal formation and composition in tree roots. The change in soil inorganic nitrogen availability by Sasa removal was small and fine root of Sasa remained even after above-ground Sasa removal, implying that maintained nitrogen uptake by Sasa attributes to stable nitrogen dynamics after the disturbance. The change in tree production, mycorrhizal formation rate, and mycorrhizal composition were also small. This study clarified that short-term effects of Sasa removal on nitrogen dynamics was small and suggest that resistance of S. senanensis to the above-ground disturbance might be the reason of the stable response of soil nitrogen dynamics.

Free Research Field

生物地球化学

Academic Significance and Societal Importance of the Research Achievements

樹木ではなく林床植生の地上部撹乱に着目して地下部応答と窒素動態の関係、樹木や外生菌根菌動態の応答を示し、いずれも短期的に変化しにくいことが明らかになった。これは、さまざまな撹乱や環境変化に曝されうる森林が細根動態や菌根菌動態を通じて森林の生産性や生態系機能を維持するメカニズムの解明において有用な知見である。また、集水域スケールで林床植生除去の影響を評価した研究はこれまでにない。社会的には、植生撹乱に対する生態系のレジリエンスがクマイザサが生育する森林では比較的大きいことが明らかになり、森林のもつ生態系サービスの維持・予測、北方林における持続的な林業の方策にも示唆を与えるものである。