Plant communities of selected urbanized areas of Halifax, Nova Scotia, Canada

Habitat origins and microhabitat preferences of urban plant species

“…While this study was only conducted on one university campus, the species we detected are common throughout Halifax (Turner et al, 2005) and consistently found in urban habitats across eastern North America (Voss, 1985(Voss, , 1996Gleason and Cronquist, 1991). Some of these species are cosmopolitan species found all over the world in urban areas (Larson et al, 2004).…”

“…In the case of Halifax, regional habitats are primarily mixed forest, thus the null expectation would be a high proportion of forest species. Forest cover is substantial within many urban areas of Halifax (Freedman et al, 1996) and remnants of natural forests are also common throughout the region (Turner et al, 2005), thus propagule availability should not be a limiting factor for urban colonization. It should be stated that the comparison of urban species origins against a crude species pool null model is not intended to be a definitive test of the Urban Cliff Hypothesis but to stimulate further research and above all, to focus attention on the habitat templates of urban areas and their possible counterparts in natural ecosystems.…”

“…The identified species were dominated by introduced, exotic species. Turner et al (2005) stated that the dominance of exotic species in the urban landscape is an indicator of the degradation of ecological integrity in these environments.…”

“…Yet ecologists have been reluctant to study the ecological systems of urban environments because they are perceived as "unnatural", and pose problems for research such as unknown disturbance histories, multiple stresses, and a lack of long-term research sites (McDonnell et al, 1997). Many naturalists and conservationists have a low regard for urban environments because these landscapes have attracted a cosmopolitan weedy flora that threatens surrounding natural habitats (Quammen, 1998;Turner et al, 2005). As researchers have become increasingly concerned with the impacts of humans on natural processes there has been recent recognition of the need to integrate human activity and cities into ecological theory and research.…”

Does urbanization explain differences in interactions between an insect herbivore and its natural enemies and mutualists?

“…The extent of impervious cover (paved surfaces, structures such as buildings and roads) causes a variety of detrimental effects on arthropods (Morse et al 2003;Sadler et al 2006;Magura et al 2008;Bennett and Gratton 2014), and it is a stronger predictor of urbanization gradients than broad classifications such as urban, suburban and rural areas (Ellis and Ramankutty 2008;Ramalho and Hobbs 2012;Savage et al 2015). Variation in structure of green spaces within cities represents the availability of habitats for arthopods in gradients of urbanization, however, green spaces within cities that present complex structures and higher plant richness are thought to be of high quality as habitats for insects (Pauleit and Duhme 2000;Whitford et al 2001;Turner et al 2005).…”