Data on bird abundance in urban woodlands in 32 Swedish cities
Hedblom, Marcus; Söderström, Bo; Sidemo-Holm, William (2022), Data on bird abundance in urban woodlands in 32 Swedish cities , Dryad, Dataset, https://doi.org/10.5061/dryad.08kprr54f
The expansion of urban areas is increasingly contributing to biodiversity declines. Several studies have analyzed the effect of increasing urbanization on bird diversity, but few have differentiated effects of urban landscapes (matrix) from changes in focal habitat quality at multiple spatial scales. In this study we analyzed the effect of urbanization on bird communities in individual (local scale) and across multiple (regional scale) cities while controlling for the quality of sampled natural habitats. We conducted bird point counts and habitat quality mapping of trees, dead wood and shrubs in 459 forest remnants along an urbanization gradient in 32 cities in Sweden. We then analyzed how the degree of urbanization affected species richness of woodland-breeding bird and red-listed bird species at a regional and local scale. We also analyzed how urbanization affected beta-diversity and dissimilarity between communities at the different spatial scales, and if dissimilarities in species communities along the urbanization gradient were driven by species nestedness or turnover. We found that urbanization decreased species richness, and the number of red-listed species, at both the regional and local scale. Dissimilarities in woodland-breeding bird communities among urban, semi-urban and peri-urban areas at the local scale were particularly due to turnover, and at the regional scale to nestedness. Since there was no difference in habitat quality among woodlands across the urbanization gradient, we conclude that landscape urbanization systematically causes poorer and more homogeneous bird communities. However, despite that natural habitats in cities contribute less to the regional diversity, they are critical to maintain the local bird communities of individual cities and their surroundings.
Svenska Forskningsrådet Formas