How do disturbances caused by large-sized mammals influence local biodiversity?: Possibilities of ecological rewilding under shrinking society

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K06089
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 39060:Conservation of biological resources-related
• Research Institution: Yamagata University
• Principal Investigator: Hiroto Enari 山形大学, 農学部, 教授 (90584128)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 撹乱 / ニホンザル / イノシシ / ニホンジカ / 多雪 / 撹乱 / 再野生化

Outline of Final Research Achievements

Recovery of large mammal populations has recently been observed in heavy snow regions. Here we focused on disturbances caused by their feeding and tried to (1) identify environmental conditions that determine the frequency of disturbances, (2) evaluate the influence of disturbances on plant diversity, and (3) estimate risk mitigation cost for excessive disturbances which result in biodiversity loss. The current key findings are: (1) whereas macaque feeding during winters rarely results in decreasing fitness of individual plants, they have a function to increase biomass of macaque food plants; (2) rooting activities of boar generate a negative impact on understory of beech forests, but contributes to enhancing plant assemblages in old conifer plantations; and (3) the destructive impacts of deer foraging during winters on plant assemblages gradually come to the surface and the risk mitigation cost to prevent such undesirable impact is estimated to increase with shrinking society.

Free Research Field

野生動物管理

Academic Significance and Societal Importance of the Research Achievements

東北地方で近年顕著に分布回復がみられるサルやイノシシは里山を代表する大型の哺乳類であるが、昨今の農林業被害の深刻化を受けて、「害獣」として広く認識されている。その結果、大規模な捕獲が各地で行われるようになった。一方で、本研究を通して、サルは植物群集を改変する生態系エンジニアになりうること、イノシシの掘り起こしは管理放棄により高齢化したスギ人工林地の多種共存を回復させるプラスの効果をもたらしうることなどが明らかにされた。これらの結果は、自律的な生態系を取り戻す「再野生化」の試みにおける、大型獣のもつ生態学的機能の理解に貢献するものと考えられる。