Perspectives in Urban Ecology

A main goal of ecological research is to recognize problems that are connected to anthropogenic uses of nature, and to figure out solutions for a better development and a higher quality of life for humans (Haber 1993). From Carl Troll’s landscape ecology developed the branch of urban ecology, which Leser characterized as “a landscape ecological field par excellence” (Troll 1973; Leser 1997, 2008; Reichholf 2007). Urban ecology is the study of ecosystems that includes humans living in cities and urbanizing landscapes (Marzluff et al. 2008). Alberti et al. (2003) defined urban ecology as the “study of ecosystems that includes humans living in cities and urbanizing landscapes. It investigates ecosystem services which are closely linked to patterns of urban development”. The interdisciplinary concept of urban ecology covers multiple branches of science which deal with the linkages and relationships between biotic communities and their abiotic environment as well as between urban nature, city dwellers and urban planners (Sukopp and Trepl 1995). Urban ecology has a long history of research, especially in Europe (Sukopp 2002). However, as an independent branch of science, urban ecology is a comparably young discipline. Only 40 years ago, researchers began to investigate urban agglomerations more in detail from an ecological point of view (Sukopp 1973). It has been shown that the specific environmental conditions in urban settings compared with rural areas give rise to very specific ecological systems and particular species combinations.

Urban agglomerations are places of increased emissions of anthropogenic pollutants into the atmosphere. Since most of these pollutants are harmful to humans, reduction of their ambient concentrations is a major issue of environmental policy on international, national, and local levels. According to Wiederkehr and Yoon (1998), air pollutants can be grouped into major and trace or hazardous air pollutants. Major air pollutants comprise six classical pollutants: sulphur dioxide (SO₂), airborne particles, nitrogen dioxide (NO₂), carbon monoxide (CO), lead (Pb), and ozone (O₃). Hazardous air pollutants can be found in much smaller concentrations than major air pollutants and include different chemical, physical, and biological agents, like volatile organic compounds (VOCs), radio-nuclides, and micro-organisms.

Since people have been settling on flood plains, they influenced the freshwater resources more or less intensely. Historically, the process of population expansion and industrial development in urban areas has proved disastrous to the quantity and quality of both surface and ground waters (Ellis 1999). Thus, for an appropriate assessment and development of urban areas, the integrated surface and subsurface water systems, including their ecological functioning, are playing an important role (Zaadnoordijk et al. 2004). Stability criteria for both quantity and quality of urban water resources are on the one hand the “natural” discharges and recharges of rivers and groundwater, which are mainly controlled by anthropogenic and climate change effects. On the other hand, diffuse and direct pollutions with innumerable complex chemical compounds determine serious challenges for a sustainable urban water resources management (Lerner 2004). Whereas climate change is primarily influencing the water volumes of the hydrological cycle in all components and its effect has been quantified continuously, the surface and subsurface water pollution and the circulation of these substances represent qualitative parameters, which could have a large impact on the urban water resources again (Zhang et al. 2004).

Between the soggy ceiling of the ground water aquifer and the uppermost interface of earth and air is the unsaturated space of soil particles and pores invisible to most surface dwellers – the vadose zone. In cities, this space can be frozen in time under buildings and sidewalks, and contaminated with various kinds and concentrations of polluting substances. With more than 50% of the world’s population living in cities as of 2007, research on the composition, function and dynamics of urban soils is of utmost importance for urban ecological questions as well as the for the wellbeing of city dwellers world wide. Even before the 50% demographic benchmark, interest in anthropogenic soils began stirring in Germany in the 1970s in Berlin and Essen (Burghardt 1995; Blume 1975). At that time, research concerns revolved around the proper classification of soils in urban areas and the dilemma of restoring and re-using former industrial sites. From the 1980s until the beginning of the 1990s, pollution of urban soils with organic and inorganic contaminants became the focus of many studies (Thornton 1991; Lux 1993; Radtke et al. 1997). Since then, research on urban soils has substantially broadened. The BMBF (Federal Ministry of Education and Research) project “Evaluation of Urban Soils” from 1993 to 1996, for example, included groundbreaking work on the chemical, physical and biological properties of anthropogenic soils, involving major soil science institutions from the universities of Kiel, Essen, Hohenheim, Halle, Rostock and Berlin. Results are presented in Blume and Schleuss (1997).

More than half of the global human population is living in urban areas, and the trend towards further urbanization is strongly increasing (MEA 2005; United Nations 2008). Hence, the majority of people globally will experience “nature” and related ecosystem services primarily within the urban fabric (Gilbert 1989; McKinney 2002; Miller and Hobbs 2002; Miller 2005; Goddard et al. 2010). There is increasing evidence that urban land uses affect profound changes in all environmental components and that humans are the main drivers of change (Sukopp et al. 1979; Pickett et al. 2001; Alberti et al. 2003; Grimm et al. 2008). Urban growth has been identified as a major threat to biodiversity (e.g. Hansen et al. 2005), but at the same time, urban regions can harbour an array of species (Sukopp and Werner 1983; Gilbert 1989; Pys?ek 1993; McKinney 2002) and contribute to the conservation of biodiversity. However, distinct urban ecosystems cannot replace totally the habitat function of (near-)natural systems (Kowarik 2011).

Ask any urban person what type of animal they see on a daily basis and the response will likely be “birds”. Whether it is their increased mobility due to flight compared to other animals, or a particular ability to adapt to changes in the environment, certain species of birds live in relatively high densities in human-dominated landscapes. Indeed, some species apparently thrive in urban habitats. The connection between birds and human settlements is not a recent one. For example, the house sparrow (Passer domesticus) is estimated to have begun its commensal relationship with humans between 400,000 and 10,000 years ago in the Middle East (Anderson 2006). Despite this ancient connection between people and birds the reciprocal nature of our interactions is just beginning to be investigated (e.g. Marzluff and Angell 2005).

The limitations of our resources and the effects of economic growth were first brought to a wider public consciousness in the 1970s report of “Limitations of Growth”. Since then, a broader discussion has started about how to save resources and how to reduce the negative ecological impacts of economic activities. In 2010, the BP oil-drilling catastrophe in the Gulf of Mexico showed us once again the fragility of eco-systems; the unappeasable hunger for cheap oil as the blood of our economic corpus continually leads to highly problematic events. And, our daily behaviour of using fossil fuels not only reduces the richness of resources but also leads to permanent pollution of the environment; global warming is only just one catchword which highlights these problems.

With the beginning “urban millennium” (UNESA 2007), our interest in the societal, economic, and ecological functioning of urban systems is rapidly increasing (Pickett et al. 2001). Half of the world’s population inhabits cities, with an increasing share of megacity dwellers or people living in mega-urban regions (Kraas 2007). Urban agglomerations steer processes from the local to the global level and urban ecological science needs to develop a deeper understanding of how matter and energy flows driven by urban ecosystems function across scales (Grimm et al. 2008; Kaye et al. 2006). While a city’s physical footprint is limited, the ecological footprint of our increasingly urbanized world is rapidly expanding. Urban agglomerations are estimated to extend on an ecological footprint of up to 200–300 times their actual physical size (Folke et al. 1997). The sustainable provision of urban ecosystem services and maintaining urban biodiversity is hence closely connected to mitigating effects of imbalanced rapid urbanization (McGranahan and Satterthwaite 2003). Accordingly, urban ecology is becoming more prominent and will determine how sustainable future cities will develop from an environmental perspective. There is an urgent need for in-depth process understanding and a more profound knowledge of land use decisions that drive the urban structure and thereby heavily impact the urban environment and the provision of ecosystem services. Actually, urban regions offer the most intense interaction of humans with ecosystems and thereby a wealth of opportunities to gain a deeper understanding of related land use processes and impacts on urban ecosystem services. However, urban ecology is intrinsically complex; it exhibits many different research facets and an overarching theory is still to be developed. A methodologically sound basis is mandatory to lay the foundation of such theoretical frameworks and to provide input for model-based research to test hypotheses in urban ecology and land use change (LUC) impacts on urban ecosystem services (Alberti 2005; Pickett et al. 2008).

The conditions for urban development have changed considerably in the last decades. This can be attributed to social and economic changes encompassing the processes of globalisation, deindustrialisation and demographic change. The corresponding economic, social and ecological impacts pose new challenges on urban development and planning. Especially those cities which have undergone a transformation from a socialist planned economy to a social market economy in the last 20 years are affected from these new challenges. The “shrinking city” is a phenomenon which sets up a new dimension in urban development. Shrinking leads to a substantial reshaping of urban structures. It is causing urban decline and decay, vacancy and underuse of lots and buildings. The effects and problems resulting from a loss of function include the rise of urban brownfields, depopulation, empty apartments and unused social infrastructure such as schools and kindergartens. This calls for new forms of action, planning and controlling of urban development processes. Urban restructuring requires measures which provide opportunities to adapt existing structures to meet the needs of a changing society and a changing economy. Urban brownfield sites and vacant buildings offer potentials for a sustainable urban development and innovative temporary uses. These potentials provide a variety of options to improve natural und built environments for the inhabitants on varying spatial scales.

This chapter presents the Planning-Horizons Study that tested a conceptual bridge from organizational research into geography. Working at different levels of managerial planning seems to have an influence on how a person makes use of his/her work-related urban neighbourhood. The study is based on organizational research by Jaques (A General Theory of Bureaucracy. Aldershot: Gregg Revivals, 1976; Requisite Organization. Arlington: Cason Hall & Co. Publishers, 1988) and the field concept by E. Wirth (Theoretische Geographie. Stuttgart: Teubner, 1979). Data collection took place at the Humboldt-Universität (employees and students) and high-tech-companies of the Berlin-Adlershof Science and Technology Park. The results are discussed in the context of interdisciplinary urban ecology, taking particular reference to L. Wirth’s study of urbanism.

In psychology, there is converging empirical evidence that it is necessary to differentiate between objective and subjective attributes of the environment and to take into account accompanying processes of perception and evaluation in examining the way humans interact with the environment. Amérigo (1990) and Amérigo and Aragonés (1997) proposed a conceptual framework to reflect residential satisfaction. We argue in favor of a much broader scope to this approach, namely studying the dynamic interaction between individuals and their residential environment, and analyzing the cognitive, affective and behavioral processes taking place in this interaction. The main tenets of this idea are illustrated in Fig. 11.1.