CADIC   02618
CENTRO AUSTRAL DE INVESTIGACIONES CIENTIFICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
A comparison of the habitat- and landscape-level effects of invasive beavers: Implications for ecology and management.
Autor/es:
C ANDERSON; A ROSEMOND; G MARTÍNEZ PASTUR; R ROZZI
Lugar:
Milwaukee (USA)
Reunión:
Otro; 93a Ecological Society of American Annual Meeting.; 2008
Institución organizadora:
Ecological Society of American
Resumen:
Background and methodsWhile its intact vegetation cover, low human population density andextensive size have led the Fuegian Archipelago (Chile and Argengina) tobe included as part of one of the world’s last remaining wilderness areas,it is also paradoxically home to a high percentage of introduced species.Among the archipelago’s exotic fauna is the North American beaver, aninvasive ecosystem engineer. To assess the beaver’s impact as an invasivespecies on habitat-level variables, we compared the direction andmagnitude of beaver impacts in both North and South America. To evaluateinvasive beaver effects at the landscape-scale, we then a) calculated theoverall physical impact of beavers (% impacted stream length and area), b)assessed the impact on stream food webs and cross-boundary energysubsidies and c) surveyed benthic macroinvertebrate fauna in 4 habitattypes (bogs, forested streams, beaver ponds and natural lakes). These datawere then used to model landscapes with and without beavers to test theeffects of this invasion on landscape-level species diversity andecosystem function.Results and conclusionsOur assessment showed that at the patch-scale, the impacts of exoticbeaver were predictable from expectations derived from North Americanstudies. Across the subantarctic landscape, beavers have invaded 30-50% ofthe archipelago’s stream networks and 2-15% of its area. By retainingorganic material in streams, beavers also enhanced the magnitude ofterrestrial organic matter flows to aquatic ecosystems. On the other hand,while at the patch level beavers significantly reduced diversity andincreased productivity, since their engineered habitats are similar tonatural landscape features (bogs and lakes), at the landscape level theirimpact on diversity was low, but the cumulative effect of theirimpoundments significantly changes energy flow in these systems. Inconclusion, we found that the effects of beavers in the world’ssouthernmost forested ecosystem are the largest land cover alterationsince the last ice age. However, invasive ecosystem engineering effectswere predictable based on underlying ecological mechanisms. For example,at the habitat-scale engineering effects were related to habitatdiversity, trophic dynamics and disturbance regimes, while at thelandscape-scale it was necessary to have an adequate comprehension of thesurrounding habitat context and species-specific characteristics of thenative assemblage. We conclude that beaver eradication strategies andsubsequent ecosystem restoration efforts should focus on the ecology ofnative ecosystems rather than the biology of this invasive species per se.