Local factors affecting the response of forested watersheds to elevated atmospheric N deposition

2020 Fiscal Year Final Research Report

• Project/Area Number: 17H03833
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Forest science
• Research Institution: Kyushu University
• Principal Investigator: Chiwa Masaaki 九州大学, 農学研究院, 准教授 (30380554)
• Co-Investigator(Kenkyū-buntansha): 福澤 加里部 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) ; 菱 拓雄 九州大学, 農学研究院, 准教授 (50423009) ; 舘野 隆之輔 京都大学, フィールド科学教育研究センター, 准教授 (60390712) ; 柴田 英昭 北海道大学, 北方生物圏フィールド科学センター, 教授 (70281798)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 窒素循環 / 森林生態系 / 土壌生態系 / 地域性

Outline of Final Research Achievements

Elevated atmospheric nitrogen (N) deposition and its ecological impact is an issue of widespread concern. However, the response of forest ecosystems to elevated N deposition may vary by local factors such as forest type, meteorological condition, and geology. This study set up several sites for N manipulation experiments with same protocols such as N fertilization and measurements across Japan to evaluate the local factors affecting the response of forest ecosystems to elevated N deposition. Results showed that N leaching and its response to N fertilization was obviously higher from Japanese cedar plantation than other forest types including Japanese oak. The relatively low N uptake by Japanese cedar s could be an important contributor to the high N leaching.

Free Research Field

生物地球化学

Academic Significance and Societal Importance of the Research Achievements

これまで欧州や米国で先進的に行われてきた森林生態系における窒素操作実験について，日本初の複数箇所における広域施肥実験サイトを立ち上げた．施肥方法や観測方法を統一することで，窒素沈着量増加に対する生態系応答をサイト間で評価することを可能にした．本研究で得られた，スギ人工林で窒素流出量が多く，窒素施肥に対する窒素流出の応答性も高いという結果は，森林の水質浄化機能という観点から，スギ人工林の管理の重要性を示唆するものである．