Abstract
The conservation of the fauna of bees inhabiting the Brazilian savanna is threatened due to changes in land use in the last decades. We investigated the composition, species richness and abundance of a bee assemblage in the vicinity of the Chapada Diamantina National Park. In addition, we compiled data on composition and diversity from another bee assemblage located in the same portion of the Cerrado, which was previously investigated by one of us almost 30 years ago, in order to produce a more complete panorama on beta diversity of bees in this region. We used a non-metric multidimensional scaling ordination analysis (NMDS) to compare composition of bee assemblages from diff erent types of open vegetation. We recorded 77 bee species (H’ = 2.95; J = 0.68), 42% of them were singletons. We collected slightly more than half of the species and 60% of the genera recorded in the bee assemblage studied three decades ago. H’ was signifi cantly lower in our area than in the previous study (t = 8.588, p <0.001), but equitability (J) was very similar. Several factors may contribute to these diff erences, including local diff erences in bee assemblage composition, diff erences in the probability of capturing the diff erent species (many rare species), factors affecting the sampling itself, and perhaps species loss over the three decades separating the two studies. The magnitude of species loss is difficult to assess because the two studies were not carried out exactly in the same area and there were differences in sampling time and sampling effort.
Highlights
Bees stand out as the dominant taxonomic group of pollinators in most geographic regions (Williams et al, 2001)
In this study we present new data on the bee assemblage of a fragment located in the middle portion of the Cerrado, in the Chapada Diamantina, an area where there is a mosaic of phytophysiognomies at short distances (Harley, 1995)
Even with sampling extending for several years, we obtained a species richness curve that did not stabilize, which should be influenced by the occurrence of many rare species (Williams et al, 2001), a similar finding of most surveys of bee assemblages
Summary
Bees stand out as the dominant taxonomic group of pollinators in most geographic regions (Williams et al, 2001). These bee populations depend on plant resources related to adult maintenance and offspring production, which include supplies of nectar and pollen (Roubik, 1989; Michener, 2007). In spite of its importance for the conservation of biodiversity, anthropic pressures on the Cerrado have increased in recent decades, mainly due to the expansion of pasturelands and croplands, including the mechanized production of grains, soybean and maize (Klink & Machado, 2005; Sano et al, 2010).
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