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Los depredadores introducidos transforman las islas subárticas de pastizales a tundra
D A Croll1, J L Maron, J A Estes
1Department of Ecology and Evolutionary Biology, Island Conservation, University of California-Santa Cruz, Santa Cruz, CA 95060, USA. croll@biology.ucsc.edu
Science (New York, N.Y.)
|March 26, 2005
Resumen
La introducción de zorros árticos alteró significativamente los ecosistemas de las islas Aleutianas. Al reducir las presas de las aves marinas, los zorros disminuyeron el transporte de nutrientes, impactando el suelo y transformando las comunidades vegetales de pastizales a matorrales.
Área de la Ciencia:
- Ecología Ecología Ecología.
- Dinámica de la red alimentaria Dinámica de la red alimentaria Dinámica de la red alimentaria Dinámica de la red alimentaria
- La biogeografía insular es la biogeografía insular.
Sus antecedentes:
- Los principales depredadores influyen en las poblaciones de presas, pero se debaten sus efectos en los niveles tróficos inferiores, especialmente en las comunidades vegetales.
- Las cascadas tróficas que alteran comunidades de plantas enteras son raras en los ecosistemas terrestres.
Objetivo del estudio:
- Investigar el impacto de los zorros árticos introducidos (Alopex lagopus) en la red alimentaria y las comunidades vegetales del archipiélago aleutiano.
- Para aclarar la vía a través de la cual las interacciones depredador-presa afectan a los ecosistemas terrestres.
Principales métodos:
- Observaciones de campo y estudios ecológicos en el archipiélago aleutiano.
- Análisis de las relaciones depredador-presa, específicamente zorros árticos y aves marinas.
- Evaluación de los niveles de nutrientes del suelo y la composición de la comunidad vegetal.
Principales resultados:
- Los zorros árticos se alimentaban de aves marinas, reduciendo significativamente el transporte de nutrientes de los ambientes marinos a los terrestres.
- La reducción de la ingesta de nutrientes llevó a una disminución de la fertilidad del suelo.
- Las comunidades vegetales pasaron de la dominación de las praderas a los ecosistemas enanos dominados por arbustos y forrajes.
Conclusiones:
- Los zorros árticos introducidos crearon una fuerte cascada trófica con impactos significativos en las comunidades vegetales.
- Las alteraciones inducidas por los depredadores en el ciclo de los nutrientes representan una vía previamente no reconocida que afecta a los ecosistemas terrestres.
- El estudio destaca los profundos efectos indirectos de los principales depredadores en la estructura y función del ecosistema.
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