窒素の制限は,CO2に対する生態系の反応の持続可能性を制限する
Peter B Reich1, Sarah E Hobbie, Tali Lee
1Department of Forest Resources, University of Minnesota, St Paul, Minnesota 55108, USA. preich@umn.edu
Nature
|April 14, 2006
まとめ
大気中の二酸化炭素 (CO2) の増加が植物の成長に及ぼす影響は,窒素の利用可能性によって制限されます. 6年以上にわたり,草原は窒素が不足したときにCO2の利益が減少し,バイオマス蓄積に影響を与えた.
科学分野:
- エコロジー エコロジー エコロジー
- 植物生物学 植物生物学
- 気候変動科学 気候変動科学
背景:
- 大気中のCO2濃度の上昇は,植物バイオマスを増やし,気候変動を緩和する可能性がある.
- CO2誘発植物成長刺激の長期的な持続可能性は,特に窒素制限条件下では不確実です.
研究 の 目的:
- 窒素 (N) の存在が,CO2濃縮された環境における持続的な植物バイオマス蓄積を抑制するかどうかを調査する.
- 二酸化炭素と窒素の供給の増加が多年生草原の生産性に及ぼす長期的な影響を決定する.
主な方法:
- 多年草原の種について,6年間のフィールド研究が行われました.
- 植物は,大気中のCO2とNの供給の環境と上昇レベルを制御した条件下で育てられました.
- 植物のバイオマス蓄積と土壌/植物のNダイナミクスは,時間とともにモニタリングされました.
主要な成果:
- 当初,高濃度のCO2は,環境条件と濃縮されたN条件の両方で,同様の方法で植物バイオマスを刺激しました.
- 4~6年後,植物バイオマスに対する高濃度のCO2のポジティブな影響は,濃縮されたNの供給と比較して,大気中のN供給下で著しく抑制された.
- この差異は,高濃度のCO2が土壌と植物のN動力学に与える影響が一時的に異なることに関連していた.
結論:
- 限られた土壌窒素の利用は,時とともに,大気中のCO2の上昇に対する植物バイオマス反応を徐々に抑制する.
- 土壌の窒素供給と大気中の窒素堆積の変動は,上昇するCO2に対する陸上の生態系の反応に影響します.
- 窒素の制限は,二酸化炭素が増加した条件下で,地球上の陸上の生産性に重大な制約を与える.
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