Method study on relative assessment for ecosystem service: a case of green space in Beijing, China

Ecosystem service assessment methods are commonly based on converting absolute service values into a monetary or energy equivalent. However, the absolute assessment value is always much higher than market price and dramatically different by different estimators. In fact, the purpose of regional ecosystem service assessments is mainly to recognize the superiority and vulnerability of the local ecosystems and explore the potential for ecological construction. Therefore, this study promotes the concept of the ideal forest equivalent and uses it as a reference point to measure the relative value of ecosystem service. A case study of Beijing was conducted ecosystem service using this relative assessment method on the support of geographic information systems (GIS) software platform. The basic data included remote sensing data, digital elevation map (DEM), a land use map, socioeconomic statistics, and climate data. The assessment results were as follows: (1) the ecosystem service for the Beijing green space was 555,234 ideal forest equivalents, which correspond to 36.38 % of the ideal forest cover in the area; (2) forest exhibited the largest proportion of service functions, which was followed by wetlands, gardens and farmland; (3) the distribution rule of comprehensive ecosystem service value was indicated; and (4) the Beijing region has the potential to improve and increase green space service functions. Finally, the results of this study recommend relevant countermeasures to ecological construction.