Introduction

Over the past 20 years the study of urban ecology has made great progress. Our understanding of urban ecosystems and their influence on ecological patterns and processes is advancing to where we can begin to formulate some generalities. Many of these advances in understanding have been due to comparative studies at a local scale, such as those using a gradient approach within a metropolitan area. However, very few of the studies to date have taken a regional or global comparative approach, and therefore, many remain as little more than case studies. Comparative research between urban areas will allow us to test the applicability of these findings and generalities in cities with different social, historical and environmental contexts. They can also identify new research questions and help focus research on important components of urban ecosystems that require further attention (McDonnell and Hahs, Chapter 5; Lehvävirta and Kotze, Chapter 31). The aim of this book, and the workshops leading up to it, was to begin a dialogue on the value (i.e. opportunities and challenges) of comparative studies in advancing our knowledge of ecology in cities and towns, and how we might begin to foster a larger number of regional and global comparative studies. Therefore, this book should be seen as an exploration of the work that has been done so far, and a discussion about how we might move our science forward.