非対称な密度依存は,熱帯の木のコミュニティの種豊富さを形作る

Liza S Comita¹, Helene C Muller-Landau, Salomón Aguilar

¹National Center for Ecological Analysis and Synthesis, 735 State Street, Suite 300, Santa Barbara, CA 93101, USA. comita@nceas.ucsb.edu

Science (New York, N.Y.)

|June 26, 2010

まとめ

多様な熱帯雨林では,珍しい樹種は,一般的な種よりも,同じ種の隣人 (同種) によりより悪影響を受けます. これは,同種の密度依存が種の豊富さや希少性に影響す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
トロピカル生物学トロピカル生物学
コミュニティエコロジーコミュニティエコロジー

背景:

種の一般性や希少性を左右する要因は,特に種に富んだ生態系では,依然として不明である.
理論的なモデルは,同じ (同種) および他の (異種) 種の隣人との相互作用が相対的な豊富さに影響を与える可能性があることを示唆しているが,経験的証拠は限られている.

研究の目的:

隣接する個体に対する種の感受性と,非常に多様な熱帯の木のコミュニティにおけるそれらの相対的な豊富さの間の関係を調査する.
同種性および異種性近隣効果が,苗木の生存に与える影響と,種の豊富さに関連して異なるかどうかをテストする.

主な方法:

180の熱帯の木種から3万本以上の苗木に適用された階層的な生存モデルを使用しました.
パナマのバロ・コロラド島からのデータを分析し,種子生存に対する同種および異種種の隣人の影響を定量化しました.
隣人効果の強さを,コミュニティ内の種の相対的な豊富さと関連付けました.

主要な成果:

同種の隣人に反応する種間の有意な変動が観察されましたが,異種の隣人はそうではありません.
同種の近隣効果の強さと種の豊富さとの間に有意な正の相関が発見されました.
珍しい種は,一般的な種と比較して,同種の隣人からのより大きな悪影響を示した.

結論:

コンスペイシフな密度依存は,多様な熱帯雨林のコミュニティ内の種の豊富さを形作る上で重要な役割を果たします.
珍しい種と一般的な種に対する同種の近隣の差異的な影響は,理論的予測に経験的支持を提供します.
これらの相互作用を理解することは,熱帯の生態系における種の一般性と希少性のパターンを説明する鍵です.

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