アフリカのサバンナの樹木覆いの決定要因
Mahesh Sankaran1, Niall P Hanan, Robert J Scholes
1Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado 80523, USA. mahesh@nrel.colostate.edu
Nature
|December 13, 2005
まとめ
アフリカのサバンナ生態系は,水の供給によって制御されます. 乾燥したサバンナでは,水は樹木の覆いを制限しますが,湿ったサバンナでは,草と木の共存を維持するために,火などの干渉が必要です.
科学分野:
- エコロジー エコロジー エコロジー
- 環境科学 環境科学
- バイオジオグラフィー バイオジオグラフィー
背景:
- 共同支配的な木と草で特徴づけられるサバンナは,重要な地球規模の生態系です.
- 森の覆いは,サバンナの生態系特性とダイナミクスに影響を与える重要な要因です.
- 資源の利用可能性と干渉体制は,サバンナ構造の推進要因として議論されています.
研究 の 目的:
- アフリカのサバンナで樹木が覆われている主な要因を調査する.
- 平均年間降水量 (MAP) がサバンナ構造に及ぼす影響を決定する.
- 降水量に基づいて安定したサバンナシステムと不安定なサバンナシステムを区別する.
主な方法:
- アフリカ全土の854のサバンナ地域からのデータの分析.
- MAPと最大木材の覆い間の関係に関する統計的調査.
- 異なる降水値の下でのサバンナ動態の比較.
主要な成果:
- MAP <650mmのサバンナでは,木材の覆いはMAPとともに線形的に増加し,水の制限を示します.
- 乾燥/半乾燥のサバンナは,水が木の覆いを制限する"安定した"システムです.
- MAP>650mmのサバンナでは",不安定"なシステムを定義して,木質の天蓋の閉鎖を防ぐために干渉が必要である.
結論:
- 降水量は,アフリカのサバンナを構成する重要な要因であり,MAPの650mmの値があります.
- サバンナのダイナミクスは,乾燥/半乾燥地域と湿気地域間で大きく異なります.
- 将来の降水の変化は,サバンナの分布と生態学的動態を大幅に変化させる可能性があります.
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