Integrating riparian Nothofagus antarctica forests to the study of beaver invasion on Tierra del Fuego

SOLER, R; MARTÍNEZ PASTUR, G; LENCINAS, MV; ANDERSON, CB

Mar del Plata

Conferencia; BIOLIEF 2011 - 2nd World Conference on Biological Invasions and Ecosystem Functioning; 2011

Most riparian forests and sourrondig areas of Tierra del Fuego Island are affected by beaver (Castor canadensis), an invasive species that drastically modifies both the structure and functioning of Nothofagus forests. Previous studies does not include to N. antarctica (ñire) which has great ecological importance as pioneer species of non-forested environments, with key reproductive strategies for habitat restoration. This study evaluates the effect of beaver impact on forest structure and natural regeneration of N. antarctica and resprouting response in Tierra del Fuego. 10 abandoned sites were selected in monospecific ñire forests. In each site, the forest structure affected by beaver was determined. Then, each site was divided into pre-dam area, dam, flooded area and a wooded area (from the edge of impact to the maximum cutting distance). The natural regeneration (number, age, height, origin) will be quantified using 1m2 plots in each sector, and the % of stumps regrowth in the wooded area will be estimated using 100m2 quadrats (near- and far-impact). We found seedlings (5-7 years old) installed in the pre-dam area (5 ind.m2), flooded area (23-42 ind.m2) and forest (3 ind.m2), with 7.8 cm in average height. The origin was 80-92% agamic in the pre-dam and flooded areas, and 100% from seeds in the forest. Also, 46% of the stumps resprouted with 4-85 cm in length. The presence of seedlings in the abandoned sites may indicate that N. antarctica could be able to regenerate the forests. It is essential to include the time since abandonment for each site.