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高濃度のCO2にさらされた熟葉林の木の炭素流と成長
Christian Körner1, Roman Asshoff, Olivier Bignucolo
1Institute of Botany, University of Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland. ch.koerner@unibas.ch
まとめ
大気中の二酸化炭素 (CO2) のレベルが上昇すると,成熟した温帯雨林の炭素流がすぐに増加します. しかし,高濃度のCO2は茎の成長や葉の枯渇を刺激せず,森林の炭素貯蔵予測に異議を唱えた.
科学分野:
- 森林生態学 森林生態学とは
- 気候変動科学 気候変動科学
- 植物生理学 植物生理学
背景:
- 大気中の二酸化炭素 (CO2) の濃度は世界的に上昇しています.
- 増加したCO2が森林の成長と炭素の蓄積に与える影響は依然として不明である.
- 森林の反応を理解することは,気候変動モデリングに不可欠です.
研究 の 目的:
- 高濃度の二酸化炭素が成熟温帯森林の炭素動態に与える影響を調査する.
- CO2の増加が樹木の成長と炭素貯蔵の強化につながるかどうかを評価する.
- 小規模な木の研究に基づいて,森林の炭素収縮に関する既存の予測に異議を唱える.
主な方法:
- フリーエアCO2放出技術 (FACE) を利用した.
- 35メートルの高さの温帯林の木に直接アクセスするためにキャノピークレーンを使用しました.
- 4年間,炭素流量,茎の成長,葉の litter 生産,そして光合成能力のモニタリング.
主要な成果:
- 高濃度のCO2にさらされた木々の炭素フルースの即時かつ持続的な増加が観察されました.
- 4年後には,茎の成長や葉の産生における有意な全体的な刺激は見つかりませんでした.
- 葉の化学と持続的な光合成能力のわずかな変化とともに,異なる樹種間の反応の変動が観察されました.
結論:
- 成熟した温帯雨林の木は,炭素の流れが増加しているが,CO2が上昇した状態ではバイオマス蓄積が増加していない.
- 森林の炭素貯蔵の現在の予測は,より小さな木の実験に基づいていますが,反応を過大評価している可能性があります.
- 森林における二酸化炭素の増加による炭素吸収の動態は複雑で,成熟した生態系におけるさらなる調査が必要である.
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