RECENT DEVELOPMENTS AND EMERGING DIRECTIONS IN URBAN
ECOLOGY
As the science of urban ecology emerged, research- ers borrowed concepts, terminology,
approaches, methodologies, and tools from a variety of other dis- ciplines (McDonnell &
Pickett 1993; Alberti 2008; McDonnell et al. 2009). Over the last 30 years, the discipline
has grown and now possesses a unique assortment of approaches, frameworks, study
loca- tions, and methodologies that delineate urban ecol- ogy from other disciplines. The
other chapters in this book give a full account of the evolution and current status of the
discipline. To wind up this short history of urban ecology, I will briefly acknowledge what
I believe are the recent developments and exciting new research directions in urban
ecology. Two approaches to the study of urban ecosys- tems that can be expressed as 1)
the ecology ‘in’ and ‘of’ cities and 2) the ecology of urbanization gradients are new
concepts unique to the discipline of urban ecology.
The recognition by urban ecolo- gists of the difference between the ecology ‘in’ and the
ecology ‘of’ cities has proved to be a significant conceptual leap forward for the discipline
(Grimm et al. 2000; Pickett et al. 2001; Alberti 2008; Wu 2008b). Studies of the ecology
‘in’ cities are typically single discipline, small scale, and located within a city, while ecology
‘of’ cities studies are interdiscipli- nary and multiscale incorporating both the ecologi- cal
and human dimensions of urban ecosystems (Grimm et al. 2000; Pickett et al. 2001). The
majority of urban ecology research to date falls into the cat- egory of the ecology ‘in’ cities
(Alberti 2008; Hahs et al. 2009).
There are only a few excellent examples of ecology ‘of’ cities studies (Alberti 2008; Hahs
et al. 2009). If the discipline of urban ecology is to advance and enhance our
understanding of urban ecosystems, it will require the active development of more inter-
and transdisciplinary ecology ‘of’ cities studies (Alberti 2008; McDonnell & Hahs 2009).
The application of the urban–rural gradient approach to the study of urban environments
(McDonnell & Pickett 1990) has proved a useful concept to ecologists around the world
(Theobold 2004; McDonnell & Hahs 2008).
It has also inspired the development of such useful concepts as the wildland–urban
interface (Radeloff et al. 2005). In addition, the study of urbanization gradients has
provided a foundation for the future development of the comparative ecological study of
cities and towns at regional and global scales (Niemelä et al. 2009; McDonnell & Hahs
2009). Urban ecologists have been building on existing, as well as creating new and
unique, conceptual frameworks in which to study urban ecosystems. For the discipline to
advance in the future it will need to enhance, refine, and embrace several con- ceptual
frameworks including the human ecosys- tem model (Pickett et al. 2001, 2008), urban
avoiders and adaptors model (McKinney 2002, 2008), ecosys- tem services (Bolund &
Hunhammar 1999; Jim & Chen 2009), sustainability (Newman & Jennings 2008), and
resilience (Berkes & Folke 1998; Alberti & Marzluff 2004; Pickett et al. 2004).
Historically, urban ecologists have focused on ter- restrial environments in developed
countries (Chapman & Underwood 2009), but new and excit- ing advances in
understanding the ecological and human dimensions of urban ecosystems will come from
the study of remnant vegetation (Florgård 2004), landscaped gardens (Gaston et al. 2005;
Felson & Pickett 2005; Tratalos 2007), green roofs (Oberndorfer et al. 2007), marine
environments (Chapman & Underwood 2009; Chapman et al. 2009), freshwater
ecosystems (Paul and Myers 2001), and studies of human health (Frumkin et al. 2004,
Tzoulas et al. 2007), aesthetics and recreation (Tyrväinen 2003), as well as urban
environments in developing countries in general (Conceicao 1994; Escobedo et al. 2006;
Cilliers et al. 2009; Song & Gao 2008).
A significant amount of the research conducted on urban ecosystems has been directed
at the popu- lation and community level with most of these studies focused on the
distribution and abundance of organisms (i.e. patterns). Shochat et al. (2006) pro- pose
the need to develop more mechanistic studies of urban ecosystems. Urban ecologists will
discover rich veins of research opportunities in the future if they explore the study of such
subjects as biogeo
