Investigating the influence of vegetation structure and floristic composition on bird assemblages

We studied the effects of vegetation structure and composition on avian species,
assemblages, and diversity. The study was conducted over a period of five days in the
Mapungubwe National Park, South Africa. The two habitat types studied were open
wooded savanna and riparian forest. Ten test sites were chosen for vegetation and avian
sampling. Vegetation was sampled for visibility (at varying height levels), height profile,
species composition, tree density, and canopy cover. Avian data was collected for
species, abundance, and presence. This was done by monitoring 60m x 60m quadrants
for 10 minutes each. Birds in the quadrant were recorded for abundance, while birds
outside were recorded only for presence. Visual identification was used to identify birds
within the quadrant, while auditory calls and visual identification were used for presence
outside of the quadrant. Our analysis statistically reflected vegetation structure and
floristic composition to determine patterns that influence avian composition rather than
species diversity. Changes in structural complexity and floristic diversity do not relate to
either losses or gains in avian species diversity, but do relate to a turnover in species
within the communities. Increased vegetation canopy cover correlated with increased
species diversity. Floristic composition appears to display the most valuable evidence of
determining the bird species assembled in each habitat, although we do not undermine the
importance of vegetation structure at the same level.