Example of an approach in urban ecology that considers three scales, with specific refe - rence to processes of change 

Context in source publication

Context 1

... diseases are related to high solar radiation, air temperatures and humidity ( K ovats & J endritzky 2006). The traditional model of the multinuclear city proposed by H arris & U llman (1945) from the Chicago School of Social Ecology is another approach to urban ecology. This includes the classification of built-up structures of cities ( Stadt- strukturtypen or Baukörperstrukturen in German). The ecological conditions of each structural type (e.g. industrial area, central business district, suburb with housing function, middle class housing quarter) are investigated and their charac- teristics may be compared. W ittig , S ukopp & K lausnitzer (1998) gave a detailed description of the built-up types in German cities. W ickop et al. (1999) used this model for their ecological studies of Leipzig. This is another widely used method in urban ecology. Urban ecology can be understood as a spatial science in the same way as geogra - phy. Therefore the scale of the studies to be carried out is important. Three differ - ent scales should be distinguished, especially in larger cities: the micro-scale of the local neighbourhood with its special built-up characteristics where the study or field experiment is carried out, the meso-scale of the district, which features a combination of different land use (built-up) types and finally the macro-scale of the total urban area, sometimes composed of different administrative entities or even cities. The results of the studies may permit a certain generalisation for the three scales and some typical neighbourhoods/districts/cities may be identified, leading to prototypes of a ‘virtual city’ ( Fig. 3). Urban ecology addresses processes in space and time. Besides the spatial dimen - sion, four main processes of change are the focus of recent research: changes in urban biodiversity, climate, human demography and economy: Urban land use significantly affects biodiversity patterns . Until the 1960s cities were perceived as ‘biological deserts’, whereas they are currently considered as ‘hotspots’ of botanic and animal diversity. Species respond quite differently to urbanisation, with a decline in native species and increase in introduced species as a general trend ( K owarik 1990). These changes in urban biota are currently regarded as major drivers of global homogenisation ( M c K inney 2006). However, regional studies have demonstrated that both native and non-native species rich - ness is higher in urban areas than adjacent areas and that non-native species may also contribute to the dissimilarity of urban floras ( K ühn & K lotz 2006). Future analysis should thus examine the role of cities in endangering or conserving bio - diversity in depth. Cities are important drivers of climate change because about 75 per cent of green - house gas emissions are produced in urban territories. Simultaneously, however, cities are especially vulnerable to climate change as Working Group II of the Inter - governmental Panel of Climate Change concludes in its 4th Assessment Report (IPCC 2007). Many components and processes of the earth system are affected, especially the atmosphere (rising temperatures and extreme weather events), the hydrosphere (rising water levels) and the biosphere (drastic changes to biodiversi - ty). Urbanised areas may serve as subject of field experiments in order to investi - gate plant responses to climate change, since temperature and CO 2 -concentrations are already increased in cities ( Z iska et al. 2003). Impacts are highly variable, but include an increased burden of diseases, increased morbidity and mortality from more frequent and intense heat waves superimposed on the urban heat is - land. Coastal megacities are particularly at risk from floods, storms and droughts ( K raas 2003 & 2007). Demographic change may also exert an influence on the anthroposphere. In high - ly industrialised countries people are growing older than ever before, while birth rate is simultaneously decreasing in countries like Germany ( K aufmann 2005). The proportion of senior citizens is expected to increase, and the pyramid of popu - lation is likely to change its shape. This causes modifications of behaviour and demand for living space, for example. However, it is indicative that demographic changes offer potential for improving the ecological conditions of cities, not only due to a reduced number of individuals and therefore demand for water, energy, transport etc., but also in the context of a decreasing pressure on land use and the possibility of alternatives to the classical growth of urban development. Con - versely, to ensure cost-efficient technical infrastructures, building density should not fall below a certain threshold (see paper of W estphal in this book). Economic Change is one of the most important factors for the function and de - velopment of urban agglomerations. A town’s role in the interregional and supra - national network of cities is affected by its economic structure and, in addition, existing economic activity dominates the urban environment. Cities have under - gone rapid changes to their economic structures during recent decades: They are becoming increasingly integrated into global supply and demand systems which depends on the process of globalisation. Alongside these developments a key fac - tor in advanced economies for urban agglomerations is the switch from industrial to service based economies; spatial characteristics of this change are the appear - ance of brownfields on former industrial land and growing demand for spaces for high-ranking services. The four above-mentioned changes are important issues to be taken into account in future urban ecological research and planning processes ( S tone 2005). Urban ecology is an interdisciplinary science where elements of the natural spheres and the anthroposphere with its socio-economic aspects must be taken into account. Therefore, integrated approaches are necessary for a more com - prehensive understanding of the ongoing processes. Research clusters, studying a particular question from different disciplinary perspectives, may be especially useful in urban ecology. Clusters may include elements of the abiotic spheres (at - mosphere, hydrosphere and pedosphere) and the biotic sphere (flora and fauna), which together form ‘the natural system of a city’, or the anthroposphere (society and economy), which forms ‘the socioeconomic system of a city’ (Fig. 1 and 3). Five Berlin universities and research institutes founded the Research Training Group ( Graduiertenkolleg , RTG 780) ‘Urban Ecology’ on April 1st 2002. The programme will end in 2011 and is divided into three terms, with each term lasting three years. The research approaches of the three terms serve as examples of the general concepts mentioned above (Tab. 1). During the first term RTG 780 organized its research on a northwest-southeast transect through the Berlin Metropolitan Area, from the inner core to the outskirts. Research on the growing conditions of neophytes, such as local temperature ( von der L ippe , S äumel & K owarik 2005), urban air quality ( W olf -B enning , D raheim & E ndlicher 2005), soil conditions in urban environments ( N ehls et al. 2006), ex - change of species along urban-rural gradients ( von der L ippe & K owarik in press) and the habitat of the kestrel ( K übler & Z eller 2005) present the results of such studies along an urban transect. Furthermore, T obia L akes and S onja P ...