Using a multi-scale approach to better understand biological invasions as a social-ecological system: The case of beavers in Tierra del Fuego

ANDERSON, CHRISTOPHER; SOLER, ROSINA MATILDE; MARTÍNEZ PASTUR, GUILLERMO

Temuco

Congreso; 1° Congreso Latinoamericano IUFRO-LE y 2° Congreso Latinoamericano IALE; 2016

Biological invasions research in Patagonia is biased towards short-term field studies focused on the quantification of a few species? ecological impacts. A multi-scale approach is needed to understand their broader spatial, temporal and social dimensions. We reviewed the case of the North America beaver, introduced to Tierra del Fuego (TDF) in 1946, and compared findings for habitat- versus landscape-level studies to determine lessons for invasive species ecology and management. While beavers decreased benthic taxonomic richness in ponds compared to streams, at broader ecological scales, they did not affect stream biodiversity; their impacts replicated natural lentic communities. Instead, watershed-scale effects occurred via changes in ecosystem function (e.g. ~70% greater organic matter retention). These results highlight the need to include a range of habitats, but most empirical and theoretical understanding of beavers come from lenga (Nothofagus pumilio) and guindo (N. betuloides) forests. However, landscape studies show invasion in ñire (N. antarctica) forests,peat bogs, grasslands and fens, where ecological and geomorphological impacts are significantly different. For example, lenga and guindo forests? regeneration is vulnerable to beaver impacts in the long-term and even active restoration has relatively low success rates, but ñire forests appear more resilient and active restoration success also varies over space and time, depending on precipitation gradients and species composition. Finally, while the majority of Argentine and Chilean ranchers support eradication and perceive the problem similarly, residents of Ushuaia display less support, even while clearly understanding the beaver?s negative effects. Overall, a multiscale perspective, even when not part of a specific study, can prove valuable to contextualize existing information. This approach allowed us to determine a deeper and more nuanced conceptual and practical understanding of the broader dimensions of biological invasions as a complex, dynamic social-ecological system that transcends a specific biological context.