Evaluating flows of recreational ecosystem services using mobile phone data: A demonstration in the megacity of Beijing

Understanding the spatial-temporal patterns of ecosystem services flow (ESF) linking different places is crucial for designing effective environmental policies. Here, we used mobile phone data of 6.24 million residents in Beijing to evaluate the recreational ecosystem services (RES) flow from the outskirts to the urban center by quantifying the dynamics of the RES flow, mapping its spatial-temporal patterns in supply and demand areas, and examining changes in the primary types of ecosystems providing the RES. We found that in October 2019 and October 2020, 26.26% and 23.95% of the residents from the 6 districts of Beijing's urban center engaged in recreational visits to the 10 districts in the outskirts, respectively. The volume of RES flow on workdays was about 17% lower than on holidays and about 29% lower than on weekends. The RES flow (visitors) hotspots exhibited a scattering pattern in supply areas of the outskirts and a clustering pattern in demand areas of the urban center. Forest and cropland ecosystems contributed the most to RES and exhibited distinct trends in their areal changes. Our study demonstrates an efficient approach for assessing the spatial-temporal patterns of RES flow at landscape scales, which can support the sustainable management of RES.