Abstract:

The implementation of the national forest city creation campaign has become a major approach to promote urban greening in China and is an important component of the country's ecological construction. However, the existing evaluation indicators for the construction of national forest cities are not fully capable of reflecting spatial changes in ecological quality and their impact on ecological quality. In this study, three national forest cities were selected, Changsha, Wuhan and Xuzhou. According to the current standards of national forest city, these cities were divided into built−up areas (BA) and planning areas (PA), respectively. The remote sensing ecological index (RSEI) was used to quantitatively analyze the spatial changes in ecological quality of BA and PA before and after the construction of forest cities. The results indicated that: (1) over the 10 years before and after the construction of forest cities in Changsha, Wuhan and Xuzhou, the RSEI in the BA after construction was higher than that before. Specifically, the RSEI increased from 0.293, 0.453 and 0.306 to 0.301, 0.470 and 0.399, respectively. (2) Influenced by urban expansion, compared to before the construction, the ecological quality of the PA in Changsha and Xuzhou showed a downward trend, decreasing from 0.610 and 0.568 to 0.471 and 0.514, respectively. In contrast, the ecological quality of the PA in Wuhan increased from 0.440 to 0.491. (3) Forest city construction was mainly concentrated in BA, where ecological quality had improved in more than half of the area through greening of residential areas and institutional courtyards, construction of wetland parks, as well as introducing native tree species. In the context of rapid urbanization, forest city construction has played an important role in ecological compensation. The RSEI can reflect the spatial distribution of urban ecological quality and has the potential to be become an evaluation indicator for the effectiveness of national forest city construction.

Key words: Forest city, RSEI index, Built?up area and planning areas, Ecological quality, Urbanization