Birds as mediators of ecological restoration in woodlands of northwestern Patagonia, Argentina

CAVALLERO L., RAFFAELE E. Y AIZEN M.

Bariloche

Congreso; VI Southern Connection Congress; 2010

Universidad Nacional del comahue

Northwestern Patagonian woodlands are the communities most affected by fire and firewood extraction. Standing dead trees are used by birds as perching structures in burned areas, increasing seedling recruitment beneath them. In National Parks it is allowed standing dead trees extraction in burned areas and this may limit natural recolonization. In November 2008, 450 seed traps were installed in 3 communities burned in 1999 to evaluate the perch effect of standing dead trees in post-fire recolonization. In each community, 75 seed traps were placed below perches and 75 were placed in clearings. Seed traps were revised three times during summer. Collected samples were analyzed looking for the presence of bird-dispersed seeds. In January 2009, 350 seedlings of B. buxifolia and R. magellanicum were transplanted in a burned community in two microsites: below shrubs and in clearings, to evaluate suitable microsites for seedling’s recruitment and to test if birds drop the seeds in high survival likelihood microsites. Perch effect was significant during the sampling season, 2980 seeds were captured, which 40% were dispersed by birds. Of the bird-dispersed seeds, 84% were found in seed traps placed below perches. Seedling survival was higher below shrubs. These results suggest that birds are good seed dispersers, dropping seeds in microsites where seedling recruitment is high. Therefore, birds develop a key role as mediators of ecological restoration in post-fire communities.