What drives land take and urban land expansion? A systematic review

Highlights

• We review 193 articles exploring determinants of land take or urban sprawl.

• We summarize causal relationships between land take and explanatory factors.

• Well-known drivers are the increase of population, GDP and transport facilities.

• Policy factors matter, e.g. political fragmentation, planning, or subsidies.

• The effect of many factors (including common policy instruments) remains unclear.

Abstract

Land take is the transformation of agricultural, natural and semi-natural spaces into urban and other artificial uses. It is closely linked to urban sprawl (low-density or dispersed urban development). Land take is a major environmental challenge, especially for biodiversity conservation, as it destroys and fragments natural habitats.

In order to assess how the scientific literature dedicated to this topic adresses the determinants of land take, we analyzed 193 scientific articles retrieved through a systematic methodology.

We summarized the causal relationships identified between land take and different explanatory factors. Among them, population and income growth, as well as the development of transport infrastructure and automobile use, are widely studied drivers that are most often found to increase land take. Political and institutional factors are extensively mentionned in the literature, suggesting that urban sprawl is not a mere result of “market forces” but is also shaped though public policies. Weak or unadequate planning, subsidies for land consumption and automobile transportation are said to increase urban sprawl, while infrastructure pricing and subsidies for urban renewal would have the opposite effect. The institutional setting, especially administrative fragmentation, reliance on local taxes, and competition between local jurisdictions, is suspected to be a major determinant of land take. The effect of many factors however remains relatively undocumented or controversial in the reviewed literature, including widely used policy instruments.

Introduction

Land take is a major cause of biodiversity decline in the world. It contributes to habitat loss and fragmentation (Krauss et al., 2010) and some forecasts evaluate that land take will be the first cause of biodiversity loss worldwide in the next years (Pereira et al., 2010; Seto et al., 2012). Land take also increases habitat degradation, pollution, as well as CO₂ emissions (Eglin et al., 2010; Foley et al., 2005; Guo and Gifford, 2002).

Land take can be defined as “the change in the amount of agricultural, forest and other semi-natural and natural land taken by urban and other artificial land development. It includes areas sealed by construction and urban infrastructure, as well as urban green areas, and sport and leisure facilities.”¹ Land take is closely linked to urban sprawl. The exact delimitation of the latter concept is debated in the literature; in a relatively commonly agreed-upon definition, urban sprawl designates land consuming urban development, which can take the form of either low-density or dispersed development – or both combined (Couch et al., 2008).

Land take does not always coincide with urban sprawl, since it can occur outside of urban or peri-urban areas (e.g. extraction sites) and new urban development causing land take is not necessarily sprawled: it can be developed at high density, mixed use, with a compact urban form. Yet excessive land take is a direct consequence of low-density development, which means the main channel to takle land take is to minimize urban sprawl. In this review, we included articles using the terminology of “land take” or “urban sprawl” and chose to consider them as equivalents, considering that articles adressing land take were also providing insights on urban sprawl, and vice-versa.

The importance of the land take issue has progressively been acknowledged by public actors and is explicitly mentioned in the international Convention on Biological Diversity (CBD) which counts the stopping of habitat loss among its core objectives (UNEP-WCMC 2015). The European Commission recommends halting net land take in the European Union by 2050.² Several European countries and regions have made quantified commitments to reduce the rate of land take (European Commission, 2012, page 17). Yet, despite expressed concern about the problem, land take continues at an unsustainable rate, even in Europe, where urban expansion is generally considered “slow” compared to other regions (EEA/FOEN, 2016). Reducing the pressure leading to land take and implementing adequate public policies inevitably means understanding the drivers of land take, their relative importance and interconnections (EEA, 2006), as well the influence of existing public policies through intended and unintended effects.

Despite a wide range of literature on the topic, to our knowledge, no systematic review of scientific articles addressing the determinants of land take is available today. We found several non-systematic reviews: two of them cover a larger topic and have only a limited section on the determinants (Ewing, 2008; Ewing and Hamidi, 2015), one focuses on factors linked to transportation (Handy, 2005) and another reviews mainly German literature about housing sprawl (Iwanow et al., 2015). Finally, Kretschmer et al. (2015) review some key references and build a mind-map of influencing factors. These reviews contribute to a more comprehensive understanding of the determinants of land take. Yet it is difficult to draw quantitative conclusions – such as which factors are well documented and which are under-studied – without following a systematic methodology.

This review attempts at describing and assessing existing research, and at summarizing causal relationships identified in a large number of scientific articles. In order to keep the work manageable, we chose to focus on publications that frame their research object as land take or urban sprawl, and that explicitly focus on identifying influencing factors. Although this offers only a partial view of the literature dealing with land take, we hope that it can support future research and contribute to assessing existing public policies, evaluating their current impacts and providing some insights to improve the management of land take.