Liyan Xu

Liyan Xu
1:00 pm - 2:00 pm
To be held virtually via Zoom
Ecosystem Service: Spatial Heterogeneity, Anisotropic Flows, and Landscape Planning / Design Implications
Liyan Xu
Assistant Professor, College of Architecture and Landscape Architecture, Peking University

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Meeting ID: 910 5815 7948
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Lecture Abstract

Ecosystem service values are an effective measurement for the performance of landscape planning and design. Although the mapping of the PROVISION of ecosystem services has witnessed a huge and yet growing body of literature, the actual REALIZATION of such services only occur when the provision meets the DEMAND, which process concerns the “movement” of the services from the providers (ecological elements) to the consumers through space, thus emphasizing the importance for understanding ecosystem service FLOWS. Specifically, in the urban context where cultural services dominate, the conveyor of such flows are typically the people themselves, and this hints for the opportunity to portrait ecosystem service flows through the observation of people’s movements and behavior. With the help of the emerging spatiotemporal big data, we can conduct such observation in a citywide spatial scope and at a fine resolution, and thus accurately map the provision, demand, and flow of ecosystem services, so as to identify the potential mismatch between the provision and demand, and optimize the ecosystem flow patterns by landscape planning and design for a better urbanism.

In this talk, I present three inter-related studies that illustrate how the idea of ecosystem service flow optimization can be implemented. The first study concerns an evaluation and spatially explicit mapping of the ecosystem service values provided by urban parks, waterbodies, and farmlands in Beijing. The study not only shows the spatially heterogeneous patterns of the ecosystem service values across the urban space, but also presents a quantitative analysis on how the accessibility, amount, quality, and spatial configuration of urban ecological elements help shape such heterogeneity. Next, utilizing the mobile call signaling data as a direction observation of human mobility, we map the “catchments” of urban parks in Beijing by portraying their realized ecosystem service flows, and further by comparing the realized service zones to the respective potential demands, we are able to cluster the parks based on their ecosystem service provision/demand relationship, and in turn identify the potentially over-crowded and under-utilized ones for future landscape planning endeavors. The last study, taking the city of Ningbo as a case, goes yet further and explicitly portrays the shape of ecosystem service flows. And with a systematic consideration of the distance-decaying characteristics of ecosystem service flows for different types of urban parks, the people’s propensity for recreational activities, and the location and quality of urban parks, we identify the problematic spots in the urban park system, and propose a solution plan which includes a city-wide re-planning of the urban green spaces, betterment designs for focal parks, and nudging-style policy proposals for encouraging people’s use of the parks. Although preliminary,  we hope these studies would shed light on a new framework for cross-scale landscape planning and design which would contribute to the quality of urbanism by optimizing ecosystem service flows.


Dr. Liyan Xu is an assistant professor at the College of Architecture and Landscape Architecture (CALA), Peking University (PKU). He holds a PhD in Urban and Regional Planning from MIT. Prof. Xu heads a joint lab – the PKU-Harvard Ecological Urbanism Collaboration, and also the Lab for Spatial-Temporal Intelligence and GeoDesign at CALA. His area of interest covers urbanization theory and international development, regional and urban ecosystem services, and also digital technologies that are related to the planning and design fields, especially their applications in the building of an Optimal Urbanism.