異常な温暖な年を経て,生態系における二酸化炭素吸収の長期的抑制
John A Arnone1, Paul S J Verburg, Dale W Johnson
1Desert Research Institute, Reno, Nevada 89512, USA. jarnone@dri.edu
Nature
|September 19, 2008
まとめ
異常な温暖な年は,干ばつを引き起こし,土壌呼吸を刺激することで,陸上の生態系における炭素吸収を減少させます. 二酸化炭素の吸収の回復には2年かかるため,頻繁な温暖化は地球の炭素吸収能力を低下させる可能性があることを示唆しています.
科学分野:
- エコロジー エコロジー エコロジー
- バイオジオケミストリー バイオジオケミストリー
- 気候科学 気候科学
背景:
- 地球上の生態系は,光合成と呼吸を通じて大気中の二酸化炭素を調節する.
- 気候変動の変動は,生態系の炭素交換 (NEE) に著しく影響を与えます.
- 温度異常のような単一の気候変数のNEEへの影響を年間スケールで定量化することは,混同要因のために困難です.
研究 の 目的:
- 生態系における二酸化炭素交換 (NEE) と炭素吸収に対する温度異常の影響を実験的に定量化する.
- 温暖化を経験した後の生態系の炭素バランスの回復時間を決定する.
主な方法:
- 4つの大きな閉じたライジメーターを使用し,それぞれに6つの複製の12,000kgの高草草原のモノリットを含んでいます.
- 4年間の研究の2年目で,一石の半分を異常な暖かい年に晒した.
- 研究期間中,NEEを含む生態系プロセスを継続的にモニタリングしました.
主要な成果:
- 温暖化に起因する干ばつにより,温暖な年の純初等生産性が低下した.
- 温暖化により,異常発生の翌年に土壌の異質性呼吸が刺激された.
- 生態系は,NEEをコントロールレベルまで回復するのに2年かかり,その結果,調査期間中に炭素の純結合が3倍減少しました.
結論:
- めったに発生しない異常な温暖な年は,生態系における炭素吸収を大幅に減らすことができます.
- 人為的なCO2によって引き起こされる可能性のある,より頻繁な温暖化現象は,地球上の炭素吸収の持続的な減少につながる可能性があります.
- これらの影響を理解することは,将来の気候変動の動態を予測するために極めて重要です.
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