アマゾニアの森林の炭素の動態と流れに干ばつの影響
Christopher E Doughty1, D B Metcalfe2, C A J Girardin1
1Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK.
Nature
|March 6, 2015
まとめ
アマゾンの干ばつが森林の炭素循環に影響する. 樹木は,成長を維持するために呼吸を減らし,炭素配分をシフトさせ,光合成を抑制したにもかかわらず,潜在的に死亡率を増加させました.
科学分野:
- エコロジー エコロジー エコロジー
- 気候科学 気候科学
- 林業 林業 林業 林業 林業
背景:
- アマゾン流域は,2005年と2010年に気候変動に関連した深刻な干ばつを経験しました.
- 以前の研究では,干ばつ後の木の死亡率の増加とCO2吸収の減少を示しました.
- 熱帯雨林の炭素循環が干ばつに与える正確な反応は,まだ完全に理解されていません.
研究 の 目的:
- 2010年のアマゾンの干ばつが森林の炭素循環に及ぼす影響を機械的に理解するために.
- 干ばつによって,純一次生産 (NPP),自己栄養呼吸,異質栄養呼吸がどのように影響されるかを調査する.
- 光合成に対する干ばつによる盆地全体の影響を定量化するために.
主な方法:
- 南米全土の13の1ヘクタールの森林地から数年のデータを活用した.
- 別々に測定されたNPP,オートロフィック呼吸,およびヘテロトロフィック呼吸成分.
- 葉のレベルとプロットレベルの測定を用いて,盆地全体の見積もりのために降雨データをスケールしました.
主要な成果:
- NPPの総量は,2010年の干ばつの間も変わらない.
- 特に根や茎のオートロフィック呼吸は,旱の終わりに著しく減少した.
- 干ばつがアマゾン全域の光合成を0.38ペタグラムの炭素で抑制した.
- 炭素の配分は,干ばつ後の1年で,細い根からキャノピーの原子力発電所にシフトした.
結論:
- アマゾンの木は,成長に関係のない自己栄養呼吸を減らすことで,干ばつ中の成長を優先しました.
- 組織の維持と防御への投資の減少は,干ばつ後の木の死亡率の増加を説明する可能性がある.
- 干ばつが熱帯雨林の炭素動態に大きな影響を及ぼし,生態系の回復力にも影響を及ぼします.
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