Browsing by Subject "LANDSCAPE CONTEXT"

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  • Kuussaari, Mikko; Toivonen, Marjaana; Heliola, Janne; Poyry, Juha; Mellado, Jorge; Ekroos, Johan; Hyyrylainen, Vesa; Vähä-Piikkiö, Inkeri; Tiainen, Juha (2021)
    Good knowledge on how increasing urbanization affects biodiversity is essential in order to preserve biodiversity in urban green spaces. We examined how urban development affects species richness and total abundance of butterflies as well as the occurrence and abundance of individual species within the Helsinki metropolitan area in Northern Europe. Repeated butterfly counts in 167 separate 1-km-long transects within Helsinki covered the entire urbanization gradient, quantified by human population density and the proportion of built-up area (within a 50-m buffer surrounding each butterfly transect). We found consistently negative effects of both human population density and built-up area on all studied butterfly variables, though butterflies responded markedly more negatively to increasing human population density than to built-up area. Responses in butterfly species richness and total abundance showed higher variability in relation to proportion of built-up area than to human density, especially in areas of high human density. Increasing human density negatively affected both the abundance and the occurrence of 47% of the 19 most abundant species, whereas, for the proportion of built-up area, the corresponding percentages were 32% and 32%, respectively. Species with high habitat specificity and low mobility showed higher sensitivity to urbanization (especially high human population density) than habitat generalists and mobile species that dominated the urban butterfly communities. Our results suggest that human population density provides a better indicator of urbanization effects on butterflies compared to the proportion of built-up area. The generality of this finding should be verified in other contexts and taxonomic groups.
  • Valdes-Correcher, Elena; Popova, Anna; Galman, Andrea; Prinzing, Andreas; Selikhovkin, Andrey; Howe, Andy G.; Mrazova, Anna; Dulaurent, Anne-Maimiti; Hampe, Arndt; Tack, Ayco Jerome Michel; Bouget, Christophe; Lupastean, Daniela; Harvey, Deborah; Musolin, Dmitry L.; Lovei, Gabor L.; Centenaro, Giada; Van Halder, Inge; Hagge, Jonas; Dobrosavljevic, Jovan; Pitkänen, Juha-Matti; Koricheva, Julia; Sam, Katerina; Barbaro, Luc; Branco, Manuela; Ferrante, Marco; Faticov, Maria; Tahadlova, Marketa; Gossner, Martin; Cauchoix, Maxime; Bogdziewicz, Michal; Duduman, Mihai-Leonard; Kozlov, Mikhail; Bjoern, Mona C.; Mamaev, Nikita A.; Fernandez-Conradi, Pilar; Thomas, Rebecca L.; Wetherbee, Ross; Green, Samantha; Milanovic, Slobodan; Moreira, Xoaquin; Mellerin, Yannick; Kadiri, Yasmine; Castagneyrol, Bastien (2022)
    Urbanization is an important driver of the diversity and abundance of tree-associated insect herbivores, but its consequences for insect herbivory are poorly understood. A likely source of variability among studies is the insufficient consideration of intra-urban variability in forest cover. With the help of citizen scientists, we investigated the independent and interactive effects of local canopy cover and percentage of impervious surface on insect herbivory in the pedunculate oak (Quercus robur L.) throughout most of its geographic range in Europe. We found that the damage caused by chewing insect herbivores as well as the incidence of leaf-mining and gall-inducing herbivores consistently decreased with increasing impervious surface around focal oaks. Herbivory by chewing herbivores increased with increasing forest cover, regardless of impervious surface. In contrast, an increase in local canopy cover buffered the negative effect of impervious surface on leaf miners and strengthened its effect on gall inducers. These results show that-just like in non-urban areas-plant-herbivore interactions in cities are structured by a complex set of interacting factors. This highlights that local habitat characteristics within cities have the potential to attenuate or modify the effect of impervious surfaces on biotic interactions.