2018 Fiscal Year Final Research Report

Sustainability of ecosystem function: changes in ecosystems with soil degradation caused by non-native species

Research Project

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Project/Area Number	16H01794
Research Category	Grant-in-Aid for Scientific Research (A)
Allocation Type	Single-year Grants
Section	一般
Research Field	Environmental and ecological symbiosis
Research Institution	Tokyo Metropolitan University
Principal Investigator	Kachi Naoki 首都大学東京, 理学研究科, 教授 (30124340)
Co-Investigator(Kenkyū-buntansha)	大澤剛士首都大学東京, 都市環境科学研究科, 准教授 (40554332) 川上和人国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員等 (50353652) 平舘俊太郎九州大学, 農学研究院, 教授 (60354099) 吉田勝彦国立研究開発法人国立環境研究所, 生物・生態系環境研究センター, 主任研究員 (70332244)
Research Collaborator	HATA Kenji SATO Nozomu KAGAYA Mitsuko
Project Period (FY)	2016-04-01 – 2019-03-31
Keywords	novel ecosystem / 小笠原諸島 / 侵略的外来種
Outline of Final Research Achievements	We clarified changes in ecosystem functions with soil degradation caused by disturbances of feral goats in oceanic islands, Ogasawara Islands. We focused on combination of ecosystem functions and species composition, which is based on a concept, “Novel ecosystem”. Seabird-mediated nutrient cycle was detected in a primary ecosystem on Minami-iwo Island, indicating the goal of nature restoration programs. Soils were rich in exchangeable Mg and mainly acidic, and grassland plant species distributed on the soils showed various responses to the soil environment. Based on the GIS database which previously established, we integrated distribution of seabird nests, soil properties, and distribution of alien invasive species. As a result of simulation based on a new model of insular ecosystem evolution, the ecological function was not recovered, in which the diversity in carnivorous invertebrate sometimes decreased after the eradication of goats.
Free Research Field	生態学
Academic Significance and Societal Importance of the Research Achievements	侵略的外来生物の攪乱によって生態系の基盤となる土壌環境が劣化した生態系の回復には、土壌の劣化の程度やそれに対する植物の反応が影響する可能性が示唆された。また、海鳥の営巣に伴う生態系外からの物質の持ち込みは、島嶼生態系の土壌環境の形成に深く関係していることが明らかになった。さらにシミュレーションの結果、駆除だけでは生態系の機能の回復は困難であることが示唆された。以上の成果は、攪乱による生態系機能の劣化の程度に応じて将来の生態系変化を予測し、適切な管理手法を提案する上で有用な知見を提供しうる。