Sammanfattning

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.

Nyckelord

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

Publicerad i

Global Change Biology
2022, Volym: 28, nummer: 21, sidor: 6152-6164
Utgivare: WILEY

SLU författare

• Sidemo Holm, William

  • Institutionen för ekonomi, Sveriges lantbruksuniversitet
    
  • Lunds Universitet

• Hedblom, Marcus

  • Institutionen för stad och land, Sveriges lantbruksuniversitet
    

Globala målen

SDG15 Skydda, återställa och främja ett hållbart nyttjande av landbaserade ekosystem, hållbart bruka skogar, bekämpa ökenspridning, hejda och vrida tillbaka markförstöringen samt hejda förlusten av biologisk mångfald
SDG11 Göra städer och bosättningar inkluderande, säkra, motståndskraftiga och hållbara


UKÄ forskningsämne

Ekologi


Publikationens identifierare

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

Permanent länk till denna sida (URI)

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