Effect of habitat disturbance on pollinator’s diversity and composition in the temperate forests of Southern South America

MORALES CAROLINA LAURA, QUINTERO CAROLINA, AIZEN MARCELO

Riberao Preto, Brasil

Conferencia; 8th IBRA International Conference on Tropical Bees and VI Encontro sobre Abelhas; 2004

International Bee Research Association (IBRA)

  Habitat disturbance can have profounder effects not only on plants but also on pollinator assemblages. We compared richness and composition of pollinator’s faunas in general, and Apiforms in particular, between disturbed and undisturbed paired sites, in 4 different forest types, along a precipitation gradient in NW Patagonia (Argentina).  We set 8 yellow water traps per site every 40 days during the 2000-2001 flowering season.  Pollinators and apiforms (44 ± 24% of all pollinator species and 45 ± 35% of all pollinator individuals) richness was significantly higher in disturbed sites than in undisturbed sites.  Nevertheless after rarefaction, differences in species richness were despicable in both cases. Thus, the higher richness in disturbed sites could be interpreted as a sampling artifact, as pollinator abundances were also consistently higher in disturbed sites. On average, similarity among disturbed sites was 4 - fold higher than similarity among undisturbed sites, however average similarity indexes were not different form randomness. The ordination based on apiforms species showed that paired disturbed sites, were closer to each other than to their paired undisturbed sites. Thus, habitat disturbance influences pollinator’s composition independently of forest type, mostly by a homogenization of the apiforms faunas. As all disturbed sites have been invaded by alien flowering species, which grow in different forest types, this homogenization in apiforms faunas may reflect to some extent the homogenization in floral resources.