Fragmentation and rehabilitation of urban forests in relation to new town development

Abstract

Hong Kong has experienced fast population growth in recent decades that demands corresponding intensification of land use in existing city areas and its countryside envelope. New towns have been built since the 1970s on previous rural lands occupied by villages, farms and adjacent hillslopes, in tandem with new lands created by reclamation from the sea using earth fills. Due to the rugged hilly topography, new town development involves sprawling up the slopes which may contain valuable forests. The massive urban growth of nine new towns accommodating 2 million people has brought extensive intrusion into farmlands and natural hill slopes, and imposed widespread influence on pre-urbanization natural and cultural vegetation. The conservation policy emphasizes protecting areas of high ecological value, which include woodlands dominated by native and mature trees. Recently, the urban planning mindset and practice have shifted to a sympathetic and synergistic attitude towards the natural landscape, especially at the city-countryside interface. The study aimed at tracking the changes in the distribution and pattern of forest canopy cover before and after the inception of Tai Po new town development in 1979 using sequential aerial photographs, maps and documents. The following aspects of the urban tree cover were explored: nature and magnitude of the positive and negative vegetation changes, geometric pattern and distribution of forest cover dynamics, fragmentation and coalescence of forest patches, present forest condition and performance, and factors and processes leading to vegetation modification and restoration. The spatial variations in forest cover were characterized by patch geometry and size, and evaluated in relation to the different stages and forms of new town development. Both the core urban areas (urban forest) and the countryside hinterland (peri-urban forest) were studied. The concepts of precision land use zoning, green infilling and assisted relay floristic in urban forestry work were proposed. The implications of the findings to the preservation and creation of high quality nature in compact urban development were discussed. The forest restoration could contribute to carbon sequestration and climate‐change adaptation in the quest for sustainable development. The findings and implications of the case study could throw light on nature conservation and restoration associated with new towns developments in the developing world.