80 Sanesi et al.: Avian Ecological Diversity Arboriculture & Urban Forestry 2009. 35(2): 80–86 Avian Ecological Diversity as an Indicator of Urban Forest Functionality. Results from Two Case Studies in Northern and Southern Italy. Giovanni Sanesi, Emilio Padoa-Schioppa, Leonardo Lorusso Luciana Bottoni, and Raffaele Lafortezza Abstract. Greenspaces and forest trees contribute to a number of environmental functions in urban environments, such as the sur- vival of urban-dwelling species (e.g., bird species). This paper analyzes the relationship between greenspace characteristics (struc- tural and spatial attributes) and the diversity of avian ecology species. This provides research findings coming from two studies conducted in Italy. Using point-count method, a quantification was done of the abundance and diversity of bird species in a num- ber of greenspaces having different structural attributes (e.g., vegetation type, tree height) and spatial characteristics (e.g., loca- tion, connectivity). Results showed positive correlations between greenspaces with a more diverse and mature forest vegetation and the number of specimens and species observed in the two studies. A positive correlation appeared also between distance to the city centre and richness and abundance of bird species. Finally, we discuss some of the main implications for enhancing the functional attributes of greenspaces by using avian ecological indicators to inform ecologically sound urban planning and design. Key Words. Urban Environments; Point-Counts; Urban Biodiversity; Forest Birds; Italy; Ecological Indicators; Urban Greenspaces. Greenspaces and forest areas are essential components of the ur- ban environment because they provide a wide range of environ- mental and social functions to cities and urban dwellers (Costanza et al. 1997; Orians 1986; Padoa-Schioppa et al. 2007; Sanesi and Chiarello 2006). Increasing levels of urban densification are call- ing attention to those measures that can mitigate urban island ef- fects (Mazza and Rydin 1997) or compensate for the overload of pollutants in (urban) air and soil (McPherson et al. 1994; Nowak et al. 2006). Citizens are also growing concerned over the the consequence of intense urbanization and its effects on their phys- ical and/or psychological well-being (Van Herzele and Wiede- mann 2003; Chiesura 2004; Sanesi et al. 2006). A healthy urban environment is often associated with the availability of large for- est areas within cities and the accessibility of such areas by urban residents (e.g., Hartig 2004; Hartig and Cooper-Marcus 2006). Forest trees are also essential for the survival of many ani- mal and plant species in urban environments. In particular, stud- ies have demonstrated positive effects of forest trees on both invertebrate and vertebrate species, such as spiders (Alaruikka et al. 2002), ants (Yamaguchi 2004), butterflies (Hermy and Cornelis 2000), carabides (Niemelä et al. 2002; Ishitani et al. 2003; Magura et al. 2005), and passerines (Wiens 1989; Keast 1990; Petty and Avery 1990; Mörtberg and Wallentinus 2000; Padoa-Schioppa et al. 2006; Ferrara et al. 2008). For example, Watts and Larivière (2004) showed how the presence of cara- bides in the urban environment could be explained by the size of green areas and the presence of indigenous forest species. Highly dense urban areas with a lack of greenspac- es and forest trees are often associated with the pres- ence of generalist species nesting in hollow trees (Em- len 1974; Lancaster and Rees 1979; Beissinger 1982). Although the influence of urban forests on species has been the focus of recent studies (Blair 1996), few contributions have ©2009 International Society of Arboriculture explored the subject by considering the biological response of species to different types and structures of forest vegetation in ur- ban environments. In this direction, this paper aims to explore the relationship between the urban forest structure and the abundance of certain bird species. We provide research findings coming from two studies conducted in Italy at northern (Milan) and southern (Bari) locations. At both locations, bird species were used as in- dicators of ecological diversity in urban environments (i.e., avian ecological diversity). Using point-count method, we quantified the abundance and diversity of bird species in a number of green- spaces of different structural attributes (e.g., vegetation type, tree height) and spatial characteristics (e.g., location, connectivity). We finally discussed some of the main implications for enhancing the functional attributes by selecting avian ecological indicators and use them to inform ecologically sound urban planning and design. MATERIALS AND METHODS Study Areas This study was conducted on sixteen greenspaces lo- cated in two main urban environments: Milan, north- ern Italy (N. 13) and Bari, southern Italy (N. 3). Greenspaces were opportunistically selected by considering the availability of supplementary data and information on forest species composition and structure at the year of their establish- ment as well as data on past and current forest management prac- tices. Selection was also based on considerations on the extension of each city and the amount of (public) greenspaces available. As a general figure, Milan (45°53’71’’N; 9°20’97’’E) ex- tends to approximately 182 km2 (72.20 mi2 ) with a population of 1,303,602 inhabitants (ISTAT, 2005). This figure rises up to 3,900,000 inhabitants when including surrounding towns and vil-
March 2009
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