New five-step planning tool makes the most of urban green spaces

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Even small areas of semi-natural vegetation, farmlands and abandoned farmlands provide important ecosystem services in urban environments. However, there is widespread loss of these non-urbanised areas (NUAs) owing to poor planning and urban sprawl. A new five-step process has now been developed that can inform effective planning to protect and enhance the value of urban green spaces.

 

NUAs can be parks, woodlands, or agricultural land and are an important part of green infrastructure, providing many environmental, social and health benefits. These include reductions in air pollution, local temperatures and noise, as well as carbon sequestration and recreational services. However, there are currently many areas in Europe at risk of ‘urban sprawl’: low density developments accompanied by the loss and degradation of NUAs.

This study proposes a five-step process to characterise NUAs and identify possible new land uses to maximise their benefits. It tests the method on three urban areas in Sicily, Italy. The first step in the process is to map land uses in each area, including categories such as agricultural, road and residential use. However, the researchers stress that this is not a high enough level of detail to fully incorporate the value of NUAs. They therefore introduce a second step of placing 30 metre grid squares on aerial photographs to make detailed records of land cover types. This allows the average ‘evapotranspiration’ of each land use to be estimated, a cooling effect caused by evaporation from the soil and the movement of water through plants.

To further describe NUAs, the researchers also propose an index of fragmentation, which indicates the size of the NUA and the number of other NUAs within 500 metres. This is important, since some land uses, such as playgrounds, might be more suited to small patches of land spread out across the city or town. To understand how local people might use NUAs, the researchers also included a measure of ‘proximity’, accounting for the number of inhabitants able to access the areas.

The study then combined these data to identify possible new land uses for NUAs that could help enhance ecosystem services. For example, areas with high evapotranspiration and low fragmentation may be converted to natural parks, but lower evapotranspiration and high fragmentation might be more appropriate for urban agriculture projects.

Finally, NUAs were assessed for compatibility with potential new land uses, for example, abandoned farmland would be more easily and productively converted to urban agriculture projects than natural parks.

The method worked well when applied to the Italian case studies, with recreational areas and community supported agriculture as the most frequently identified prospective land use. The researchers note that there are small improvements that could be made to the method, for example, using ‘remote sensing’ techniques could estimate evapotranspiration more accurately than using averages for each land use. However, they conclude that, overall, this new procedure can be used as a powerful tool to protect and enhance urban green spaces, since it provides local administration with a range of different possibilities to address new land use of NUAs, aimed at enhancing ecosystem services provision in an urban context.

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