Mechanisms leading to the development of alternative stable states in peatland vegetation during secondary succession after disturbance by volcanic ash

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K12139
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Chuo University
• Principal Investigator: Hotes Stefan 中央大学, 理工学部, 教授 (20401185)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: vegetation / alternat. stable states / disturbance / volcanism / resilience

Outline of Final Research Achievements

Medium term and short term effects of tephra deposition on mire vegetation were investigated in a field experiment and laboratory experiments. In the field experiment, treatments mimicking tephra deposition led to divergent responses of the dwarf shrub Myrica gale after five to eight years, indicating the development of alternative stable states. After 20 years, the cover of M. gale had declined, showing that the alternative state with high cover was not maintained. In the laboratory experiments, effects of acid precipitation and tephra deposition were tested. Strongly acid precipitation (pH2) supressed Sphagnum growth, whereas acid precipitation (pH4) and tephra deposition allowed fast recovery. Interactions between tephra particles and acid in the solution applied as precipitation apparently played a role in reducing the detrimental effect of the acid on Sphagnum growth.

Free Research Field

Landscape ecology

Academic Significance and Societal Importance of the Research Achievements

活火山が広く分布する日本において、火山灰降下や火山性酸性雨が生態系に及ぼす影響を解明することは、基礎科学だけでなく、防災・減災の観点からも重要である。本研究では、降下火山灰や火山性酸性雨の湿原植生への影響を野外実験と室内実験において解明した。広域的に堆積する数センチ程度の火山灰による植生の変化は、数年で元に戻ることが確認できた。火山が排出するガスによって、酸性雨が発生することがあるが、ミズゴケへの悪影響は、自然界でめったに起きない強酸性の場合に限って確認された。広域に降下する火山灰の影響が一時的で、種組成や種の被度の変化による遷移が起こり得るが、元の状態が回復することが予想される。