Multiscale heterogeneity within and beyond Taipei city greenspaces and their relationship with avian biodiversity

Abstract

Urban habitats are often studied as green fragments in a developed landscape, with opinions diverged on the importance of local versus landscape effects. We propose to replace this “local” versus “landscape” framework with a more precise construct using urban greenspace as the focal scale. Within-greenspace heterogeneity was defined by the multiple elements within each greenspace, whereas beyond-greenspace heterogeneity was defined by the green versus grey elements surrounding each greenspace. The avifauna species in 283 Taipei greenspaces were surveyed and analyzed using this framework. The urban avifauna was found to be associated with five different habitat types, conferring upcoming opinions that highlight the importance of fine-scaled heterogeneity in urban landscapes. Within-greenspace factors were more important than beyond-greenspace ones in explaining species composition and richness. Isolation effects were found only for birds associated with forests but not others because the large natural areas around the city were all forests. Although the city sits at the convergence of two rivers, the tall-grass/shrub and water-related birds associated with riparian systems were poorly represented. Synanthropics and exotics were mostly open woodland and ground/short-grass birds, whose habitat preferences overlapped with human preferences in landscaping. This suggests that human preferences in landuse and landscaping may affect ecosystems in ways beyond mere fragmentation. Ecosystem types that coincide in location with human preference in landuse or exhibit physical structures that do not meet human preferences are particularly at risk. The implications of such human impacts should be seriously considered in the conservation of biodiversity in an increasingly human-dominated world.