降雨の変動,炭素循環,メシク草原の植物種の多様性
Alan K Knapp1, Philip A Fay, John M Blair
1Division of Biology, Kansas State University, Manhattan, KS 66506, USA. aknapp@ksu.edu
Science (New York, N.Y.)
|December 14, 2002
まとめ
降雨量の変動が増加しても,降雨量の総量は変わらないが,草原の生態系が変化する. 極端な気象パターンは土壌の水分,植物の多様性に影響を与え,炭素循環と生産性を低下させた.
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
- 環境科学 環境科学
背景:
- 一般的な循環モデルは,降雨の変動性の増加を予測しています.
- 草原の生態系は,降雨パターンの変化に敏感である.
- 変化した降雨に対する生態系の反応を理解することは,将来の環境変化を予測する上で極めて重要です.
研究 の 目的:
- 降雨変動の増加が,原生草原の生態系に与える影響を評価する.
- 嵐の頻度と強さの変化が土壌の水分,植物の多様性,炭素循環に及ぼす影響を調査する.
- 土壌の水分変動と地上の純一次生産性 (ANPP) の間の関係を決定する.
主な方法:
- ネイティブの草原で4年間の実験が行われました.
- 降雨パターンは,嵐の頻度を減らし,嵐毎の降雨量を増加させることで操作されました.
- 測定には,土壌の水分,植物種の多様性,土壌のCO2流量,CO2吸収,ANPPなどが含まれていました.
主要な成果:
- より極端な降雨パターンは,土壌の水分と植物種の多様性の時間的変動を増加させた.
- 炭素循環プロセス (土壌のCO2流量,CO2吸収,ANPP) が減少しました.
- ANPPは,平均土壌含水量よりも,土壌水分の変動に対してより高い反応性を示した.
結論:
- 予想される降雨変動の増加は,炭素循環の重要なプロセスを急速に変化させる可能性があります.
- 降雨パターンの変化は,総降水量に関係なく,植物集団の組成に独立して影響を与える可能性があります.
- 草原の生態系は,極端な降水量の変化に脆弱であり,重要な生態学的機能に影響を与えます.
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