The distribution and configuration of tree cover in urban Hong Kong

The urban tree cover of a sample area in Hong Kong, selected for its exceptionally good tree cover that penetrate the built-up matrix, was mapped at 15000 scale using aerial photographs. Distribution and configuration of cover was quantified by systematic line sampling. Sampled segments were assigned to appropriate habitat types, urban zones and land uses. Chi-square analysis was employed to detect associations between some observed pairs. Attributes to characterize tree cover and habitats were proposed. Tree cover was found predominantly on slopes well mixed with the urban matrix. Patches of trees in roadside habitats and offroad open spaces were small and disconnected in rigid geometric patterns. Natural slopes unaffected by urban development supported woodlands at high elevation outside the city boundary. Cover in artificial or natural residual slopes (undeveloped slopes embedded within the urban matrix) showed wide variations. Most of the narrow curvilinear units were oriented along contours and situated between roads and buildings. Cover and segment size increased progressively from coastal reclaimed zones to the upslope lands. Areas of high-density land use had scanty cover; most tree cover was found outside subdivided lots in places of lower density land use. Topographical control of urban morphology, habitat and cover characteristics were evident. The dimension, orientation and connectedness of the largely unplanned residual-slope cover were inadequate as wildlife refuges. The principles and possible applications of island biogeography theory in the urban setting was assessed. The dynamic interaction between urbanization and tree cover was summarized. Potential for neighborhood nature parks should not be wasted. Possibilities to protect and enhance tree cover and mould its configuration in a landscape plan in existing and new urban areas were discussed.