Abstract
Urban nature is often severely fragmented and only small isolated patches occur in a matrix of developed areas. This project will be the first comprehensive survey study ever performed on a national level to answer questions about factors affecting urban biodiversity. Birds will be surveyed from May to August in >500 urban parks distributed over 36 cities. These data will be used to answer whether critical thresholds exist, at a city level, in the proportional area of urban forest fragments. We will also examine species richness and community structure in relation to local habitat quality and matrix quality at multiple scales (along urban-rural gradients and in agricultural and forest-dominated landscapes). Thus, we will determine the relative influence of factors affecting biodiversity at local and landscape scales. Using an experimental approach, we will assess movement rates of butterflies along habitat corridors. Which species and habitat corridor characteristics, respectively, promote dispersal? Furthermore, reproductive success of hole-nesting birds will be investigated along an urban to rural gradient, and across forest ecotones, to test if reproductive rates are associated with patterns of density. This experimental approach will allow us to measure the relative importance of emigration and local reproductive rates in explaining local extinction.
Sweden