Assembly rules allow to test quantitatively the resilience of riparian plant communities to beaver invasion in sub-Antarctic forests

P WALLEN; CH ANDERSON; G MARTÍNEZ PASTUR; MV LENCINAS

BUENOS AIRES

Congreso; IV Reunion Binacional de Ecología; 2010

This study quantifies the resilience of riparian herbaceous communities of subantarctic forests in Chile and Argentina to beaver invasion. We characterized the divergence in compositional and spatial structure of species co-occurrence, comparing pristine and impacted communities along a beaver meadow age sequence. Assemblages were characterized from field surveys carried out between 2002–2006 in Tierra del Fuego island. Principal Component Analysis was performed to compare species composition between pristine and different aged meadows created after beaver impact, and a co-occurrence index (C-score) was used to measure divergence in spatial structure of assemblages. Spatial structure as well as vegetation composition of meadows showed an increasingly divergent trend from unmodified sites to beaver meadow with greater age. These results indicate that understory vegetation in deciduous subantarctic forests are not resilient to beaver invasion impacts, and therefore, this introduced species is expected to homogenize landscape diversity of riparian ecosystem and threaten native riparian forest vegetation assemblages.