ABSTRACT
Traditionally, urban areas have been regarded as locations of low biodiversity that are dominated by non-native species (Alvey, 2006). Many studies have provided evidence to show that urban and suburban areas can rather contain relatively high levels of biodiversity (Jim and Liu, 2001; Araújo, 2003; Godefroid and Koedam, 2003; Cornelis and Hermy, 2004). Urban forests can play a crucial role for the conservation of many species of flora and fauna and they can therefore be actively managed by foresters and city planners to preserve that diversity. Moreover, urban forests and in general vegetation occurring in urban areas (like parks, patches of woodland, residential areas or other components of a green infrastructure) can comprise a significant percentage of a nation’s tree canopy, leading their management to have important effects not only to a local but also to a national scale (Florgård, 2010; Baffetta et al., 2011). Biodiversity in forests can be preserved at high levels by maintaining large and undisturbed natural habitats. However, in urban and suburban areas this may be not feasible because of little natural areas remaining (Alvey, 2006) and negative pressures coming from the urban system. Urban habitats may provide refuges for species whose native habitats have been greatly diminished (Gavareski, 1976; Mills et al., 1989). Unfortunately, only small and isolated natural patches persist in urban areas and they attract people living in cities, being therefore affected by multiple stressors (Ficetola et al., 2007). Due to their fragility in representing suitable natural habitats and the direct disturbance caused by large numbers of visitors, it is therefore urgent to protect biodiversity of residual forested patches, because for many species they represent the only available habitat (and this can be particularly important for rare or endemic species) (Ficetola et al., 2007). Undertaking good practices of management of vegetation in the urban ecosystem is therefore a great strategy for the sustainability of human development and for cities’ resilience (Kraxner et al., 2016).
