Ecological Indicators 42 (2014) 1–5 Contents lists available at ScienceDirect Ecological Indicators j o ur na l ho me page: www.elsevier.com/locate/ecolind Compact, eco-, hybrid or teleconnected? Novel aspects of urban ecological research seeking compatible solutions to socio-ecological complexities Salman Qureshi a,b,∗ , Dagmar Haase a,c a Department of Geography, Humboldt University of Berlin, Rudower Chaussee 16, 12489 Berlin, Germany b School of Architecture, Birmingham City University, 5 Cardigan Street, Birmingham B4 7BD, UK c Helmholtz Centre for Environmental Research – UFZ, Permoser Str. 15, 04318 Leipzig, Germany a b s t r a c t Scientists in this urban century have published numerous studies proposing a wide range of theoretical and technical methodologies for addressing the complex challenges posed to urban livelihoods. The most critical challenge that has yet to be overcome is how to respond to the demands of decision- makers who seek ready-made and rapidly implementable solutions for sustainable urban development. This paper introduces and briefly discusses the contemporary concepts and overarching ideas in urban ecology research, which should be of relevance to the wide range of compact, yet sprawling, and eco-cities, as well as to researchers investigating the ecology of cities. This work serves as an introduction to the Special Issue of Ecological Indicators resulting from the First Congress of the Society for Urban Ecology, held in Berlin in July 2013. A combination of theoretical and technical papers is included. A mixture of exploratory urban indicators is proposed, and some existing indicators are further tested with novel methods in cross-continental, interdisciplinary case studies. © 2014 Published by Elsevier Ltd. 1. The ‘urban phenomenon’ Cities occupy approximately 4% of the world’s total land sur- face (Ramankutty et al., 2006) but accommodate more than half of the world’s population, and this number will only continue to increase (Lutz et al., 2001; United Nations, 2011a), especially in developing countries (Grimm et al., 2008; Wu, 2008). Hence, urban- isation has been proven as a major driving force of global change and sustainability (Qureshi et al., 2014; Wu, 2008). The unprece- dented growth of human populations and rapid urban development have led to several urgent questions regarding the future of human life and its quality in cities (Elmqvist et al., 2013; Qureshi et al., 2013). These factors will have an increasingly significant impact on the biophysical assets of the environment on multiple scales (Berry, 1990; Millennium Ecosystem Assessment, 2005). The rapid expansion of cities complicates the continuum of the urban fabric, which leads to rapid and unsustainable changes in the dynamics of peri-urban and surrounding rural areas, including agricultural lands (Pauliet et al., 2010; Breuste et al., 2013). ∗ Corresponding author at: Department of Geography, Humboldt University of Berlin, Rudower Chaussee 16, 12489 Berlin, Germany. Tel.: +49 030 2093 6803; fax: +49 030 2093 6848. E-mail address: salman.qureshi@geo.hu-berlin.de (S. Qureshi). As an irreversible and intensive phenomenon, urbanisation affects flora, fauna, atmosphere and soils in urban areas. Cities and their peri-urban surroundings are primarily human-dominated ecosystems (Williams et al., 2009). Therefore, Wu et al. (2011, p. 1) claim that “urbanisation is the most drastic form of land use change affecting biodiversity and ecosystem functioning and ser- vices far beyond the limits of cities”. Any threats to these critical ecosystems will lead to serious challenges across the world, includ- ing energy crises, climate change, ecosystem instability and human health issues, all of which affect societal well-being (Seto et al., 2012; Williams et al., 2009; Müller and Munroe, 2014; Pauchard et al., 2006). However, any positive impact of technological and scientific development in cities will help make our world more sustainable (Haase, 2014). Many of these ‘Janus-faced’ situations face urban areas. For example, while the loss of arable land reduces ecosystem pro- ductivity, the loss of urban green space has a negative impact on human health and well-being (Rohde and Kendle, 1994; Tzoulas et al., 2007; Ulrich, 1984). Changes in urban vegetation cover lead to alterations in the microclimate of the human habitat, as well as in climate dynamics and the environment at local and regional scales (Gill et al., 2007; Lehmann et al., this issue). These effects origi- nate from urban areas, but their influence extends into peri-urban and rural areas and continues into natural environments such as forests, mountains and rivers. Therefore, the pattern of the urban- rural gradient is constantly influenced by human pressure and the http://dx.doi.org/10.1016/j.ecolind.2014.04.017 1470-160X/© 2014 Published by Elsevier Ltd.