Dagmar Haase

Birds and the city: urban biodiversity, land use, and socioeconomics.

We examined bird diversity in relation to land use and socioeconomic indicators in Leipzig, Germany. We used neighborhood diversity (ND) and bivariate correlation to show that the potential to experience biodiversity in a city is associated with population density, household income, unemployment, and urban green space. People living in urban districts with high socioeconomic status experience the highest species richness around their homes, whereas lower social status increases the chance of living in species-poor neighborhoods. High-status districts are located along forests, parks, and rivers that have a high quantity and quality of green space. However, green space in general does not guarantee high bird diversity. We conclude that bird diversity mirrors land use and socioeconomic patterns within the compact European city of Leipzig. Therefore, urban planning should focus on decreasing these patterns and protecting the remaining species-rich green spaces.

Actors and factors in land-use simulation: The challenge of urban shrinkage

Both modelers and social scientists attempt to find better explanations of complex urban systems. They include development paths, underlying driving forces and their expected impacts. So far, land-use research has predominantly focused on urban growth. However, new challenges have arisen since urban shrinkage entered the research agenda of the social and land-use sciences. Therefore, the focus of this paper is a twofold one: Using the example of urban shrinkage, we first discuss the capacity of existing land-use modeling approaches to integrate new social science knowledge in terms of land-use, demography and governance because social science models are indispensable for accurately explaining the processes behind shrinkage. Second, we discuss the combination of system dynamics (SD), cellular automata (CA) and agent-based model (ABM) approaches to cover the main characteristics, processes and patterns of urban shrinkage. Using Leipzig, Germany, as a case study, we provide the initial results of a joint SD-CA model and an ABM that both operationalize social science knowledge regarding urban shrinkage.

Dealing with Sustainability Trade-Offs of the Compact City in Peri-Urban Planning Across European City Regions

The compact city has become a leading concept in the planning of peri-urban areas. The compact city concept is often advocated as “sustainable” because of claims that include lower emissions and conservation of the countryside. The literature shows, however, that there are certain trade-offs in striving for compaction, especially between environmental and social aspects of sustainability. In this article, we describe expressions of the compact city concept in the planning practice of several European urban sample regions, as well as policies and developments that contradict the compact city. We look at examples of positive and negative impacts of the compact city that were observed in the sample regions. Further, we discuss attempts by planners to deal with sustainability trade-offs. Being aware that developments in the peri-urban areas are closely connected to those in the inner city, we compare the sample regions in order to learn how the compact city concept has been used in planning peri-urban areas across different contexts in Europe: in Western, Central and Mediterranean Europe, and with growing, stable or declining populations. We conclude with recommendations with respect to balance in applying the compact city concept.

Endless urban growth? On the mismatch of population, household and urban land area growth and its effects on the urban debate.

In European cities, the rate of population growth has declined significantly, while the number of households has increased. This increase in the number of households is associated with an increase in space for housing. To date, the effects of both a declining population and decreasing household numbers remain unclear. In this paper, we analyse the relationship between population and household number development in 188 European cities from 1990–2000 and 2000–2006 to the growth of urban land area and per capita living space. Our results support a trend toward decreasing population with simultaneously increasing household number. However, we also found cites facing both a declining population and a decreasing household number. Nevertheless, the urban land area of these “double-declining” cities has continued to spread because the increasing per capita living space counteracts a reduction in land consumption. We conclude that neither a decline in population nor in household number “automatically” solve the global problem of land consumption.

The urban-to-rural gradient of land use change and impervious cover: a long-term trajectory for the city of Leipzig.

Urbanisation is arguably the most significant form of land use change as it has various impacts on the pattern, functionality and dynamics of landscapes. Such effects become particularly obvious if observed and analysed along an urban-to-rural gradient. This article presents a case study on long-term land use and impervious cover change along the urban-to-rural gradient in the German city of Leipzig – a special case because the urban region underwent dramatic societal changes during the past 100 years experiencing both world wars, socialism and transition to market economy. To depict this development we use small scale land use data based on topographic maps from 1870 to 2006. The results show that urbanisation is a strongly non-linear process. In summary, we found the urban-to-rural gradient had a strong tendency to decrease with regard to the percentage of impervious cover with a simultaneous increase of the total impervious cover. This trend is strengthened further by the fact that Leipzig has been growing little in terms of economy and population but rather experienced some form of de-densification in recent decades. The urban-to-rural gradient offers a promising approach to firstly integrate historical data into current land use change impact assessment and, secondly, to uncover effects of iterative and simultaneous phases of urban growth and decline.

Omnipresent Sprawl? A Review of Urban Simulation Models with Respect to Urban Shrinkage

Simulation models on urban land-use change help in understanding urban systems and assist in urban planning. One of the challenges of simulating urban regions in Europe as well as in North America or Japan is urban shrinkage, where deindustrialisation, massive population losses, and ageing cause unforeseen (or unexpected) commercial and housing vacancies in cities. In order to set up a conceptual framework for model improvement to assist such challenges, we review recent urban land-use-change simulation models, using four different modelling approaches: system dynamics, linked transport — urban models, cellular automata, and agent-based modelling. The focus of the review is to assess the causalities and feedback mechanisms that were implemented in these models. The results show that simulation models are very heterogeneous in implemented mechanisms leading to urban land-use dynamics. No single model fulfils all of the criteria required to model urban shrinkage in a spatially explicit way. However, system-dynamic models that are documented in the literature can serve as a good starting point for spatially nonexplicit simulation, and one example was found for linked transport — urban models which encompasses aspects of urban shrinkage. The potential of cellular automata is unclear as spatially explicit data on vacancies to feed this class of models is usually not available. Agent-based models appear to be the most promising approach for spatially explicit modelling of urban shrinkage.

Towards a flood risk assessment ontology – Knowledge integration into a multi-criteria risk assessment approach

Abstract Flood risk management must rely on a proper and encompassing flood risk assessment, which possibly reflects the individual characteristics of all elements at risk of being flooded. In addition to prevalent expert knowledge, such an approach must also rely on local knowledge. In this context, stakeholder preferences for risk assessment indicators and assessment deliverables hold great importance but are often neglected. This paper proposes to put this body of information into operation in form of a knowledge base, thereby making it accessible and reusable in multi-criteria risk assessment. Selected use cases discuss the advantages of such a semantically enhanced assessment approach.

Simulating Demography and Housing Demand in an Urban Region under Scenarios of Growth and Shrinkage

After the fall of the Berlin wall in 1989, demographic decline and urban shrinkage brought massive changes in the housing stock in East German cities. Urban planners and policy makers face complex problems caused by the resulting vacancies and demolitions and the handling of urban brownfields in the inner city. At the same time, cities are under ongoing pressure of suburbanisation. Because existing models focus mainly on demographic and urban growth and their impact on housing stocks, we present a simulation model that is able to compute both growth and shrinkage processes. We uncover nonlinear dynamics and feedbacks between demography, housing preference, and supply of housing space. The simulation results show that, despite population decline, the increasing number of single households leads to a growing total housing demand in the central parts of the study area. Beyond this area, residential vacancies in multistorey housing segments will remain regardless of population growth. At the same time, the simulations show that, despite population shrinkage and an overall oversupply of flats, there is a negative net demand for flats in affordable prefabricated housing estates as the percentage of low-income households increases. These findings will help planners modify or adapt their visions of the residential function in shrinking cities and to adjust current programmes of renewal and restructuring.

Land use impacts of demographic change – lessons from Eastern German urban regions

Demographic change has become a major topic regarding the use and stability of European urban regions. It can be seen as the major driving force responsible for “growth” and “non-growth” or “decline” pathways in urban regions for the coming decades. Growing and shrinking urban regions do exist simultaneously next to each other. The trend towards further urban sprawl and dispersion observed in the 1980s in western Europe and the 1990s in East Central Europe accompanying the transition process are about to be replaced by shrinkage and perforation. This is mainly due to the recent decrease in birth rates, ageing and shifting household structures. This chapter analyses the trends and spatial patterns of the impact of demographic changes in urban regions. In the first part different features of demographic change are presented. In the second part, the paper expands on how demographic change affects urban land use, fabric, housing markets, infrastructure and greenery. Since eastern Germany has been shrinking substantially since 1990, the paper uses this example to show a case in point embedded into the overall European context.

Bridging the gaps between design and use: developing tools to support environmental management and policy

Abstract Integrated assessment models, decision support systems (DSS) and Geographic Information Systems (GIS) are examples of a growing number of computer-based tools designed to provide decision and information support to people engaged in formulating and implementing environmental policy and management. It is recognised that environmental policy and management users are often not as receptive to using such tools as desired but that little research has been done to uncover and understand the reasons. There is a diverse range of environmental decision and information support tools (DISTs) with uses including organisational and participatory decision support, and scientific research. The different uses and users of DISTs each present particular needs and challenges to the tool developers. The lack of appreciation of the needs of end-users by developers has contributed to the lack of success of many DISTs. Therefore it is important to engage users and other stakeholders in the tool development process to help bridge the gap between design and use. Good practice recommendations for developers to involve users include being clear about the purpose of the tool, working collaboratively with other developers and stakeholders, and building social and scientific credibility.