Content area
Full Text
Landscape Ecol (2008) 23:11431155 DOI 10.1007/s10980-008-9253-4
RESEARCH ARTICLE
The use of gradient analysis studies in advancing our understanding of the ecology of urbanizing landscapes: current status and future directions
Mark J. McDonnell Amy K. Hahs
Received: 30 July 2007 / Accepted: 12 August 2008 / Published online: 28 August 2008 Springer Science+Business Media B.V. 2008
Abstract Over the past decade, the urbanrural gradient approach has been effectively used to study the ecology of cities and towns around the world. These studies have focused on understanding the distribution of plants and animals as well as ecosystem processes along gradients of urbanization that run from densely urbanized inner city to more rural exurban environments. We reviewed 300 papers investigating urbanization gradients that were published in peer-reviewed journals between 1990 and May 2007. Sixty-three percent of the papers investigated the distribution of organisms along urbanization gradients. Only ve papers addressed the measures used to quantify the urbanization gradient itself. Within the papers addressing the distribution of organisms, 49% investigated the responses of birds to urbanization gradients, and \10% of the papers investigated more cryptic organisms. Most of these studies utilized a variety of broad measures of urbanization, but future advances in the eld will require the development of some standardized broad measures to facilitate comparisons between cities. More specic measures of urbanization can be used to gain a mechanistic understanding of species
and ecosystem responses to urbanization gradients. While the gradient approach has made a signicant contribution to our understanding of the ecology of cities and towns, there is now a need to address our current knowledge gaps so that the eld can reach its full potential. We present two examples of research questions that demonstrate how we can enhance our understanding of urbanization gradients, and the ecological knowledge that we can obtain from them.
Keywords Urbanrural gradients
Biodiversity Landscape ecology
Urbanization Characterizing urban landscapes
Melbourne, Australia Auckland, New Zealand
Tree species richness
Introduction
The ever increasing human population is driving the expansion and creation of cities and towns worldwide. The process of urbanization changes the landscape, generating more impervious surfaces and articial structures (Gilbert 1989; Collins et al. 2000; McKinney 2002). It also results in high densities of people, domestic plants and animals, while also altering the...