Why do we keep losing agricultural land
Demographics, economic growth and policies are key drivers to urban sprawl.
Urban sprawl needs to be tackled at the national or regional levels.
A key to curb urban sprawl lies in re-thinking density.
The urbanisation trend raises very salient questions for food security and agriculture next to the cities. However, surprisingly, even if the phenomenon is well documented, there had not been, to date, any thorough literature review on its causes.
What are the main factors explaining urban sprawl, and what can we do about it? In a paper published in Land Use Policy, researchers from France-based think-tank IDDRI and research centre CIRED review all the factors discussed in scientific literature.
Demographics, economic growth… and policies
The first driver that comes to mind is economic growth. As a country gets richer, demand for housing, leisure and production spaces booms. However, the researchers found that it is not all about economic growth. Indeed, urban sprawl can vary greatly between countries with similar growth rates.
Existing literature points to other drivers:
- Demographics (and migrations): the more people, the bigger the cities? The causal relation is not that easy, as in most European countries, for example, cities are growing faster than the population. So it is necessary to also take into account the number of people per household, and the housing choices people make. If the size of households decreases or if they choose to live in individual houses, demographics will greatly impact urban sprawl.
- Policies, such as transport planning. Transport infrastructure tend to generate sprawl as they make new areas accessible for development. Indeed, cities that have developed dense transport networks are less prone to sprawling.
Which drivers are the most important? The scientific literature is not yet mature enough to answer this question. According to Alice Colsaet, the article’s lead author, it is interesting to see that policies are always mentioned as a driver, but their actual weight is not well characterised. More research is therefore needed on this topic.
Agriculture caught up in urban sprawl
Can agriculture resist urban sprawl? It will depend on whether it is able to hold back the city. If agriculture is profitable and dynamic, it helps maintaining agricultural surfaces.
The reviews reveals key features that help keeping peri-urban agriculture alive: high agricultural land prices, high profitability (that prevents farmers to selling to other uses), high productivity and low parcel fragmentation.
Density: the new urban frontier
What can be done to curb urban sprawl? Urban planning is the first lever. For instance, transport networks should be carefully designed to foster density rather than sprawl, and urban renewal be made a priority.
A key lies in re-thinking density. According to Alice Colsaet, we still miss collective representations about what liveable density could look like, not only for cities, but also for economic activity zones or rural areas.
Today, urban planning is facing a few dilemmas when it comes to density. For instance, if a policy encourages new development with substantial green areas to improve residents’ well-being, it also contributes to urban sprawl. Cities need to be creative to find ways to accommodate both dense areas and green space.
Is urban planning the key to curbing urban sprawl?
Local planning is not, however, the only lever. First, because local authorities are caught in a double bind that requires them, on the one hand, to curb urban sprawl, but, on the other, to compete with their neighbours in order to attract population, economic activities (and taxes resources).
Second, because, more generally, urban sprawl needs to be tackled at the national or regional levels. Only at this scale can a country reflect upon internal migrations and prevent some areas to become more attractive while others are losing residents. This is also the right scale to allocate efforts between territories, and make urban sprawl objectives truly operational, by incorporating them in overarching urban planning documents. For instance, Alice Colsaet highlights that, in France, it is difficult to analyse local planning document’s efforts to curb urban sprawl as there are no national indications about what exactly is “enough urbanisation”. It is therefore time to invest in national policies to prevent cities from threatening food security.
Urban Food Futures would like to thank Alice Colsaet for her inputs and comments.
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