As human populations grow, our impact on natural areas beyond urban centres is rapidly increasing. There’s a need to estimate not only where people live and work, but also where humans are found in the more remote and natural areas which are often the targets of protection efforts.
“Apart from a few well-monitored national parks, spatial patterns of human recreational activity remain largely unknown,” says Associate Professor Noam Levin from CEED and the University of Queensland.
“This lack of accurate data about human presence in more natural and remote areas handicaps conservation, management, policy, and investment decisions.”
Remote sensing provides a useful tool for mapping land-cover changes such as deforestation, however it doesn’t help us map people moving through the landscape. Levin and colleagues have attempted to fill this gap through an innovative analysis that combines information from social media with remote sensing.
“We combined an analysis of ‘big data’ coming out of Flickr, a social media site where people load up their geo-tagged photos, with remote sensing data that records artificial night lights,” explains Levin.
“We used data from the Flickr photo-sharing website as a surrogate for identifying spatial variation in global visitation, and complemented this estimate with spatially-explicit information on stable night lights between 2004 and 2012. The night lights help us identify urban and industrial centers.”
Natural and semi-natural areas attracting visitors were defined as areas both highly photographed and non-lit. The researchers confirmed that the number of Flickr photographers within protected areas was a reliable surrogate for estimating visitor numbers by comparing the information with local authority censuses.
While most photos are taken by people outside protected areas, the millions of Flickr photos uploaded to the internet combined with night-light imagery allows researchers to map and quantify, for the first time, worldwide visitation of both protected and unprotected areas. This enables the identification of visitation hotspots (and coldspots) for multiple countries and ecoregions across the world.
“The technique we have developed has many applications,” says Levin. “It can be useful for assessing the gaps of future protected areas, help in devising strategies, and enhance the effectiveness of protected area management in relation to pressures created by visitors.”
Their analysis also tells us what the most popular national parks in the world are.
“The most photographed protected areas globally included Yosemite and Yellowstone National Parks in the United States and the Lake and Peak Districts in the United Kingdom,” says Levin.
“Two of the most photographed but largely unprotected sites are Brazil’s Pantanal and Bolivia’s Salar de Uyuni.”
The study is now available in the journal Ecological Applications.
Levin N, S Kark & D Crandall (2015). Where have all the people gone? Enhancing global conservation using night lights and social media. Ecological Applications 25: 2153–2167. doi:10.1890/15-0113.1
TOP: Holiday photo from the Lake District, UK, posted onto Flickr (by rockabilly_girl, Flickr CC BY-SA 2.0).
FOLLOWING: Photos and night lights. Satellite-derived night lights averaged between 2004 and 2012 (in purple) and Flickr photographers (in green). Areas with both Flickr photos and night lights are shown in white, unlit areas with Flickr photos are shown in green, lit areas with few or no Flickr photos are shown in magenta, and unlit areas with no Flickr photos are shown in black.