关键词: 广州, 树冠覆盖, 功能分类, 城市森林

Abstract:

Tree canopy coverage landscape was analyzed based on the design framework of function classification and scale system in the urban region of Guangzhou. The results showed that the ratio of tree canopy coverage was 19.5%, with the highest (26.5%) in Tianhe district, and the lowest (6.6%) in Fangcun district. Ecological beneficial forests were dominant among the five types including ecological benefit forests, public garden, residential forests, production forests and special protective forests. The coverage ratio of ecological beneficial forests was highest and accounted for 55.4% of total tree canopy, and the production forests took second, with 19.9%. The ecological chunk forest had the largest mean acreage, while roadside trees was the smallest. The coverage ratio of extra large patches, with each area larger than 1 hm², was 78.8%, and the ratio of small-sized(<0.1 hm²), medium-sized (0.1-0.5 hm²)and large-sized patches(0.5-1 hm²) was 9.2%, 7.9% and 4.2%, respectively. Extra large-sized patches were dominated in ecological beneficial forests and production forest stands, while other sized patches were regnant in residential forests . Extra large-sized patches were mostly distributed in the mountainous area, which located in the north of the urban region and the eastern developing belt in Tianhe and Huangpu districts, and orchard fields in the south of Haizhu district as well. Number of the planted small-sized patches was the most in the old city area. Most of the large-sized patches were adjacent to the extra large-sized patches, and the pattern might be caused by the fragment of extra large-sized patches in the process of urbanization. Continuous tree canopy is an effective approach for implementing the continuity of ecological progress and pattern. Roadside trees type, being the most at patch numbers and fragmental relatively, has the most potential for forming continuous coverage patch via spatial linkage. The results provided valuable information for related research of urban forest and landscape pattern optimizing at small scale in Guangzhou.

Key words: Guangzhou, tree canopy coverage, function classification, urban forest