| dc.description.abstract | Biogeography comprises the study of patterns of the geographic distribution of organisms
and the factors which govern those patterns. The study was implemented from the
Samanalawewa river basin (480 m Mean Sea Level (MSL)) to Haagala peak (1420 m
MSL), at Issengard Biosphere Reserve, Belihuloya, in the Sabaragamuwa province in Sri
Lanka. Along the 10 horizontal line transects at 100 m intervals, bird identification, as
well as measuring of vegetation and habitat parameters were conducted over nine months
at one month intervals in the complete elevation gradient. A total number of 97 bird
species were recorded including 86 resident, 21 endemic, 19 threatened, 7 montane, and
11 migratory. Adding evidence to the mid-domain effect, species richness, abundance,
and diversity of birds indicated the hump-shaped variation along the elevation gradient.
Both species richness and Shannon Wiener diversity have shown the highest values at
700 m MSL and the highest value in abundance at 580 m MSL. Above 0.8 higher,
Shannon Wiener evenness value shows ecosystem stability at each elevation. Habitat
complexity, tree height, and canopy cover, with several avian community parameters
showed similar patterns of variation along the elevation gradient. Hence, the responses of
avian communities along the elevation gradient are supported by vegetation and habitat
topography. The leeward side of the forest patch at the highest elevation contributed to
enhancing the faunal and floral community assemblages resulting in increment in species
richness, habitat complexity, tree height, and canopy cover at the highest elevation. | en_US |
