Avian diversity in pine forests along an urban-rural/agriculture-wildland gradient

To understand the role of pine forests in an urban/agricultural matrix for avian diversity conservation, we investigated how avian species richness (number of species) changes along an urban-rural/agriculture-wildland gradient. We conducted bird surveys and vegetation surveys in pine forests in central-east Georgia, during 2010-2011 breeding seasons. We classified an urban-rural/agriculture-wildland gradient into seven classes. We performed the rank analysis of covariance and pairwise comparisons (based on the overlap of 90 % confidence intervals). Significant differences in avian species richness were found among seven classes (P < 0.05). Species richness was lower in pine patches embedded in wildland matrix compared to those in urban and/or agricultural matrix. Lower diversity was associated with relatively low structural diversity of vegetation in pine patches within the wildland matrix. Although most results of pairwise comparisons were insignificant, species richness of shrub nesting species, migrant species, and pine-grassland species was higher at pine patches in a mixture of low level of urban and agricultural land use and/or in low level of agricultural land use. Our results suggest that while pine forests in wildland are crucial habitats for conservation-important species, pine forests in some human-altered landscapes may also play a positive role for avian diversity conservation.