URBAN ECOLOGY IN A CHANGING WORLD
Among the many branches of ecology, the urban ecology is nowadays one of the most important disciplines. The urban ecology is focusing the complex relationships of living organisms among them, and with their environment in an urban context. Urban areas constitute one of the fastest growing land-use types at the global scale (McDonald, 2008). The city of Haiku, Hainan (China), photo Y. Benedetti.
HISTORY OF URBANIZATION
In a very interesting study led by the University of Yale and published in Scientific Data, authors show the history of urbanization, 3700 BC – 2000 AD. The study compiled the most comprehensive dataset on historical urban populations to date, showing the rise of human cities, beginning with [arguably] the world’s first city in 3700 BC and continuing up to the present.
Since 2008 more than 50% of the global human population and almost 80% of the population in developed countries has lived in cities (United Nations, Dept. Econ. Soc. Affairs, 2014), and predictions for the near future suggest an increase to 85% by 2050 (Ferenc et al., 2014).
BIOTIC AND EVOLUTIONARY HOMOGENIZATION
Among the most evident effects of urbanization, we can mention the range expansion of cosmopolitan and non-native species accompanied by simultaneous range contractions of specialist, regional, and endemic species. As a consequence, the replacement of specialist by generalist species in space and time, mixing the taxonomic composition and increasing the similarity between communities, constitutes the “biotic homogenization” (McKinney, 2006).
In a global scale study, we demonstrated that urbanization reduces also the overall evolutionary diversity of species assemblages. Our findings shown that urban areas hold few and less evolutionary unique species than non-urban areas, highlighting the important role that cities play in the homogenization process of biodiversity (Morelli et al. 2016; Ibáñez-Álamo et al. 2016).
URBAN BIRDS AS BIOINDICATORS
The use of species as bioindicators is rather useful in ecological assessments. Bird species indicators, as for instance proposed in the development and application of the Farmland Bird Indicator (FBI), are widely used in many countries of Europe (Gregory et al., 2005).
Many species or group of species were proposed as a surrogate for identifying hotspots of species richness or other characteristics of the environment during the last decades. Some few examples: Fleishman et al., 2005; Wierzcholska et al., 2008; Jones et al., 2016. From a single bird species (Eagle owl, Bubo bubo) proposed as indicator of mortality of bird communities in association to human structures as power pylons (Pérez-Garcia et al., 2016), to considering species traits to assess the bioindicator potentialities of birds (Carrascal et al., 2012), as well as a niche-based approach (Butler et al., 2012). Furthermore, a set of few common species as a potential indicator of high nature value farmlands (Morelli et al. 2014). Photos Passer italiae by F. Pruscini.
CEMETERIES AS BIODIVERSITY ISLANDS IN THE CITIES
Urban greenery is the cornerstone on the conservation of biodiversity in cities. However, there is an urgent need for increased biodiversity conservation and to develop better management strategies to deal with this imperative in urban areas. In this direction, the identification of urban patches which can operate as buffer areas or refuge to protect the biodiversity is a useful tool (urban parks, gardens, tree-lines in the roadsides, etc.).
In some studies, we confirmed that cemeteries work as urban parks, supporting high evolutionary uniqueness in urban bird species, as well as increasing overall species richness and the functional diversity of communities. Additionally, we found that some avian species can adapt their escape behaviour to the characteristics of human activities (in urban parks or cemeteries).
PARTITIONING THE EFFECTS OF URBANIZATION ON BIODIVERSITY
Federico Morelli and Jiri Reif are editors of the Research Topic (RT) “Partitioning the effects of urbanization on biodiversity: Beyond wildlife behavioural responses to a multilevel assessment of community changes in taxonomic, functional and phylogenetic diversity” for Frontiers in Ecology and Evolution.
The main aims of the RT are to collect a robust set of original scientific evidence, to assess the impact of specific elements of urbanization and/or pollution on different and complementary diversity metrics. Contributors have to provide original articles by combining field data, geospatial analysis and modelling procedures, delivering new insights on identification of problems and pitfalls related to the interactions between humans, plants and animals in human dominated environments.