Since the second half of the 20th century, urban shrinkage has become a common pathway of transformation for many large cities across the globe. Although the appearance of shrinkage is fairly universal—typically manifested in dwindling population, emerging vacant spaces, and the underuse of existing urban infrastructure, ranging from schools and parks to water pipelines—its essence is hidden from view. Phenomena related to shrinkage have been discussed predominantly using terms such as decline, decay, blight, abandonment, disurbanization, urban crisis, and demographic change. Amongst others, these concepts were typically related to specific national contexts, installed in distinct explanatory frameworks, based around diverging normative accounts, ultimately leading to very different policy implications. Yet there is still a lack of conceptualization and integration of shrinkage into the wider theoretical debates in human geography, town and country planning, urban and regional studies, and social sciences at large. The problem here is not only to explain how shrinkage comes about, but also to study shrinkage as a process: simultaneously as a presupposition, a medium, and an outcome of continually changing social relationships. If we wish to understand shrinkage in a specific location, we need to integrate theoretical explanations with historical trajectories, as well as to combine these with a study of the specific impacts caused by shrinkage and to analyse the policy environment in which these processes take place. The authors apply an integrative model which maps the entire process across different contexts and independently of local or national specifics; it covers causes, impacts, responses, and feedback loops, and the interrelations between these aspects. The model does not ‘explain’ shrinkage in every case: instead, it builds a framework into which place-specific and time-specific explanations can be embedded. It is thus a heuristics that enables communication, if not comparison, across different contexts. With the help of this model, the authors hope to find a way in which shrinkage can be studied both in a conceptually rigorous and in an historically specific way. Instead of an invariant ‘process of shrinkage’, they portray a ‘pluralist world of shrinkages’.

The issue of urban shrinkage has become the new ‘normal’ across Europe: a large number of urban areas find themselves amongst the cities losing population. According to recent studies, almost 42 per cent of all large European cities are currently shrinking. In eastern Europe, shrinking cities have formed the overwhelming majority – here, three out of four cities report a decrease in population. Shrinkage has proved to be a very diverse and complex phenomenon. In our understanding, a considerable and constant loss of population by an urban area classifies it as a shrinking city. So, while the indicator of shrinkage used here is rather simple, the nature of the process and its causes and consequences for the affected urban areas are multifaceted and need to be explained and understood in further detail. Set against this background, the article presents, first, urban shrinkage as both spatially and temporally uneven. Second, this article shows that the causes of urban shrinkage are as varied as they are numerous. We explore the ‘pluralist world of urban shrinkage’ in the European Union and beyond. The article provides an original process model of urban shrinkage, bringing together its causes, impacts and dynamics, and setting them in the context of locally based urban trajectories. The main argument of this arrticle is that there is no ‘grand explanatory heuristics’ of shrinkage; a ‘one-size-fits-all’ explanatory approach to shrinkage cannot deliver. To progress and remain relevant, one ought to move away from outcome-orientated towards process-orientated research on urban shrinkage.

During the last three decades, the countries of the developed world have been engulfed by the 'second demographic transition', which involves new family relations, less and later marriage, declining fertility rates, population ageing, postponement of child-bearing and smaller households, among other trends. It is being increasingly argued that such population dynamics are having a powerful transformative effect on the inner city, by diversifying and redensifying its social landscapes, and creating a 'splintered' urban form. Based on the findings of a recent EU Framework 5 research project, this paper investigates the demographic contingencies of this process-also known as reurbanisation-in four European cities: Leipzig (Germany), Ljubljana (Slovenia), Bologna (Italy) and Leon (Spain). Analyses of census and municipal registry data, as well as on-site questionnaire surveys and interviews, have revealed that the reviewed cities are being populated with, and fragmented by, multiple migration trends and new household structures connected to the second demographic transition.

This opinion paper discusses urban lawns, the most common part of open green spaces and urban green infrastructures. It highlights both the ecosystem services and also disservices provided by urban lawns based on the authors’ experience of working within interdisciplinary research projects on lawns in different cities of Europe (Germany, Sweden and Russia), New Zealand (Christchurch), USA (Syracuse, NY) and Australia (Perth). It complements this experience with a detailed literature review based on the most recent studies of different biophysical, social, planning and design aspects of lawns. We also used an international workshop as an important part of the research methodology. We argue that although lawns of Europe and the United States of America are now relatively well studied, other parts of the world still underestimate the importance of researching lawns as a complex ecological and social phenomenon. One of the core objectives of this paper is to share a paradigm of nature-based solutions in the context of lawns, which can be an important step towards finding resilient sustainable alternatives for urban green spaces in the time of growing urbanisation, increased urban land use competition, various user demands and related societal challenges of the urban environment. We hypothesise that these solutions may be found in urban ecosystems and various local native plant communities that are rich in species and able to withstand harsh conditions such as heavy trampling and droughts. To support the theoretical hypothesis of the relevance of nature-based solutions for lawns we also suggest and discuss the concept of two natures—different approaches to the vision of urban nature, including the understanding and appreciation of lawns. This will help to increase the awareness of existing local ecological approaches as well as an importance of introducing innovative landscape architecture practices. This article suggests that there is a potential for future transdisciplinary international research that might aid our understanding of lawns in different climatic and socio-cultural conditions as well as develop locally adapted (to environmental conditions, social needs and management policies) and accepted nature-based solutions.