Understanding the Impact of abandonment and natural disasters on Satoyama ecosystems: A case study of Sado island

2024 Fiscal Year Final Research Report

• Project/Area Number: 21K05826
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 41030:Rural environmental engineering and planning-related
• Research Institution: Nagano University
• Principal Investigator: Mitsuo Yoshito 長野大学, 環境ツーリズム学部, 教授 (90736951)
• Co-Investigator(Kenkyū-buntansha): 安田 浩保 新潟大学, 災害・復興科学研究所, 研究教授 (00399354)
• Project Period (FY): 2021-04-01 – 2025-03-31
• Keywords: 耕作放棄 / 生態系管理 / 里山 / 水田

Outline of Final Research Achievements

Given the increase in abandoned farmland and the intensification of natural disasters due to climate change, our aim was to achieve a comprehensive understanding of Satoyama ecosystems in a depopulating society and to develop sustainable agricultural practices and Satoyama management methods. We conducted a quantitative evaluation of the impact of paddy field cultivation status and topographical characteristics on aquatic animal communities. The analysis for loach showed no clear relationship between cultivation status and their probability of occurrence, although some trends were observed with watershed area. On the other hand, paddy fields located on sloping terrain in mountainous areas showed a significantly higher loach biomass per unit water surface area compared to those on flat land. This suggests that differences in the topographical characteristics of paddy field locations significantly influence the habitat conditions of aquatic organisms.

Free Research Field

保全生態学、群集生態学

Academic Significance and Societal Importance of the Research Achievements

本研究では山間と平地という水田立地の地形的違いがドジョウの生息量に違いをもたらすことが明らかになった。さらに、ドジョウの胃充満度や成長率に関する解析から、生息量の違いは生息地間における摂餌量及び成長率の違いに起因していることも示唆された。本研究結果は、耕作放棄が里山生態系にもたらす影響が水田の立地条件によって異なる可能性を初めて明確に示すものである。現在水田の耕作放棄は平地に比べ山間部等の傾斜地で顕著に進行しているが、本研究結果はこうした土地利用変化の地形的偏りを踏まえた生態系管理方策の構築に向けた基礎的情報となると考えられる。