Landscape Ecology of Birds on Mount Leconte, Great Smoky Mountains National Park
Landbirds form a significant component of wildlife resources in the Great Smoky Mountains National Park. The present study explored how forest structure and composition of deciduous-coniferous ecotones influenced diversity, richness, and relative abundance of bird species and how bird species responded to the spruce-fir community. Using a form of the variable-circular plot method, I conducted audio-visual censuses of diurnal birds on Mount LeConte. I established 212 geo-referenced census points on six trails, which were used as gradient-oriented transects (gradsects). I measured habitat characteristics at the same census points. I used forest community types for each point on gradsects to delineate boundaries. I applied "The Tasseled-Cap (T-CAP)", a graphic description of the spectral-temporal development of locations, to analyze bird-habitat relationships in order to investigate the utility of Landsat T-CAP indices in predicting forest patterns and bird species' richness and abundance. I derived elevation, slope, and aspect from differentially corrected GPS coordinates using ArcView Spatial Analyst and T-Cap indices from Landsat TM remotely sensed data for forest community types and each vegetation sampling station using Earth Resources Data Analysis System. My results showed correlations among the abundances of many bird species and elevational, floristic, and physiogonomic features of their habitat, both for univariate and multivariate characters. Both cover type and size class (dbh) were important to the breeding avifauna; various groups of breeding birds were associated with either one or both variables. Ecotones along the gradsects among forest types were perceived by many bird species as significant discontinuities. Zones of both rapid and gradual change in bird abundance were observed. For certain bird species, patterns of bird distribution and forest types coincided. Individual species responded to patchiness, vegetation structure, and elevation, sometimes in a predictable manner. I observed clusters of species and communities along my derived zones that appeared to be different. Species expanded or contracted their distributions in localities where the homogenous ecotone was displaced upward or downward in elevation relative to the location of the ecotone on Mount LeConte. Spatial fluctuations were, in general, related to zonal transitions in forest types. T-CAP indices were related to species' responses to changes in landscape structure and composition. Distinct patterns in vegetation that corresponded with different forest types and zones of rapid and gradual change in bird abundance were observed. Greenness and wetness values differentiated closed canopy fir stands from all other classes.
Birds, Great Smoky Mountains National Park, Landscape ecology, Mount Leconte, Ecology and Evolutionary Biology
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