Abstract

Urbanization is a major contributor to biodiversity declines. However, studies assessing effects of urban landscapes per se (i.e., disentangled from focal habitat effects) on biodiversity across spatial scales are lacking. Understanding such scale-dependent effects is fundamental to preserve habitats along an urbanization gradient in a way that maximizes overall biodiversity. We investigated the impact of landscape urbanization on communities of woodland-breeding bird species in individual (local scale) and across multiple (regional scale) cities, while controlling for the quality of sampled habitats (woodlands). We conducted bird point counts and habitat quality mapping of trees, dead wood, and shrubs in 459 woodlands along an urban to rural urbanization gradient in 32 cities in Sweden. Responses to urbanization were measured as local and regional total diversity (gamma), average site diversity (alpha), and diversity between sites (beta). We also assessed effects on individual species and to what extent dissimilarities in species composition along the urbanization gradient were driven by species nestedness or turnover. We found that landscape urbanization had a negative impact on gamma-, alpha-, and beta-diversity irrespective of spatial scale, both regarding all woodland-breeding species and red-listed species. At the regional scale, dissimilarities in species composition between urbanization levels were due to nestedness, that is, species were lost with increased landscape urbanization without being replaced. In contrast, dissimilarities at the local scale were mostly due to species turnover. Because there was no difference in habitat quality among woodlands across the urbanization gradient, we conclude that landscape urbanization as such systematically causes poorer and more homogeneous bird communities in adjacent natural habitats. However, the high local turnover and the fact that several species benefited from urbanization demonstrates that natural habitats along the entire urbanization gradient are needed to maintain maximally diverse local bird communities.

Keywords

beta diversity; biodiversity; birds; city; forest; red-list; urbanization; woodland

Published in

Global Change Biology
2022, Volume: 28, number: 21, pages: 6152-6164
Publisher: WILEY

SLU Authors

• Sidemo Holm, William

  • Department of Economics, Swedish University of Agricultural Sciences
    
  • Lund University

• Hedblom, Marcus

  • Department of Urban and Rural Development, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss
Make cities and human settlements inclusive, safe, resilient and sustainable


UKÄ Subject classification

Ecology


Publication identifier

DOI: https://doi.org/10.1111/gcb.16350

Permanent link to this page (URI)

https://res.slu.se/id/publ/118328