More than half of the global population currently lives in cities, and this is projected to increase significantly by the end of the century. As cities expand in size, their green spaces, including remnant natural areas, nature reserves and urban parks, will come under increasing pressure from human activities. Both managed and unmanaged green spaces are important as locations or people to exercise, get closer to nature, destress and improve their mental health. However, there is a delicate balance between allowing human access and conserving natural ecosystems.
Parks and other green spaces are also important for preserving ecosystem biodiversity and for providing services such as stormwater management and heat reduction. When people utilize green spaces, they can affect these functions, for example by disturbing wildlife and forging new trails that are then subject to erosion. It is therefore important for green space management strategies that the numbers and activities of visitors are measured in some way. This should not be invasive, but must be at a fine enough scale to inform management decisions.
Researchers from the University of Toronto and Conservation Halton have now partnered to test the usefulness of anonymized GPS data from peoples’ smartphones to quantify the extent to which green spaces are used, and for what purposes. Conservation Halton is a local conservation authority responsible for managing natural areas, protected reserves and urban parks in the regional municipality of Halton, Ontario. The various green spaces total around 1,000 km2 and include forests, riverside vegetation and grasslands. More than 1.2 million visitors use these spaces each year, most of them from nearby large urban centers.
Visitors to the green spaces often take part in activities such as hiking, dog walking, cross-country skiing and picnicking, and GPS data from visitors’ smartphones can be a powerful tool in understanding what activities are taking place and how many people are present.
The researchers in the current study used Mapbox Movement to obtain an anonymized activity index representing visitor density aggregated to 100 x 100 m grid cells and two-hour windows. They developed new methods for the synthesis, management and analysis of this GPS data from smart devices in the Conservation Halton green spaces in order to understand how this data compares with traditional measures of human access and activity, and to investigate whether the activity index can be used to infer human presence and activity in green spaces in future.
Alessandro Filazzola and colleagues present their findings in a paper in the open-access journal PLOS Computational Biology. They found that the GPS data did indeed capture insights about people’s use of these green spaces, showing, for instance, that mobile device activity was strongly correlated with data on reservations made by people to access parks.
The data also revealed which areas within green spaces had more or less human activity, with established trails being particularly popular. In addition, greater human presence was linked to certain types of land cover, such as rock formations, as well as certain tree species. These findings highlight the potential for anonymized GPS smartphone data to help inform management of green spaces, especially as cities grow worldwide. Such efforts could optimize the benefits of green spaces for people while also preserving biodiversity and other ecosystem services.
The experts note several challenges to this approach, such as some people’s tendency to disconnect from their mobile devices when visiting green spaces and the difficulty of distinguishing between a smart phone located within a green space and one that is in a car passing just outside the perimeter. Future research could address these issues and refine the methodology.
“Access to parks is important for city residents for recreation, connecting to nature, and socialization, but it’s challenging to understand how people use these green spaces,” said the researchers. “Our study is using anonymized mobility data to help shed light on the relationship between people and nature in parks.”
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