高濃度のCO2は,乾燥した生態系における生産性と侵入種の成功を高めます
S D Smith1, T E Huxman, S F Zitzer
1Department of Biological Sciences, University of Nevada, Las Vegas 89154-4004, USA. ssmith@ccmail.nevada.edu
Nature
|November 18, 2000
まとめ
大気中の高濃度のCO2は,湿った年,乾燥した年ではなく,乾燥した生態系における灌木の成長を大幅に促進する. この変化は,侵襲的な草を好み,砂漠の生態系を潜在的に変えてしまう.
科学分野:
- エコロジー エコロジー エコロジー
- 気候変動 生物学
- 植物生態学 植物生態学
背景:
- 乾燥した生態系は,地球の土地の20%をカバーし,気候変動に敏感です.
- 大気中の二酸化炭素の上昇は,地球規模の気候変動の主要な原動力である.
- モハベ砂漠の生態系は,環境条件の変化により,潜在的な変化に直面しています.
研究 の 目的:
- モハベ砂漠の生態系における植物生産に対する高濃度の大気中のCO2の影響を調査する.
- 降雨の変動が,増加したCO2に対する砂漠の植物の反応にどのように影響するか評価する.
- 増加したCO2が,原産植物種と侵入植物種に与える影響の違いを判断する.
主な方法:
- 無傷の砂漠環境でフリーエアCO2濃縮 (FACE) 技術を活用した.
- 主要な多年生灌木の新芽生えを監視した.
- 定量化された地表生産と,原生および侵襲的な"年草の種雨.
主要な成果:
- 主要な多年生灌木の新芽の生産量は,高い降雨量のある年に50%のCO2増加で倍増しました.
- 高濃度のCO2は,干ばつのある年の間,灌木の生育を増加させなかった.
- 侵襲的な"年草は,本土種と比較して,二酸化炭素が上昇した状態で,生産と種雨の増加が大きいことを示しました.
結論:
- 高濃度のCO2は,乾燥した地域で植物生産を大幅に高めることができますが,この効果は降雨によって調節されます.
- 増加したCO2は,モハベ砂漠のネイティブ種よりも侵襲的な"年草を好む.
- この種の組成の変化は,北米の砂漠における火災サイクルを加速させ,生物多様性を減少させ,生態系機能を変化させる可能性がある.
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