Impacts of intensive urbanization on trees in Hong Kong

Abstract

Trees in cities face a severe limitation of plantable space and an exceptionally stressful growing environment. In Hong Kong, shortage of developable land has relegated trees to a lower priority and intensified urban impacts on them, relative to other cities. The vicissitudes of urban growth and trees since the founding of Hong Kong are reviewed, and eleven specific conflicts between urbanization and trees in Hong Kong are described. Redevelopment of existing buildings has raised site coverage by impervious surface and taken away ground-level planting space within and around affected lots. Infilling of relatively low-density areas mainly for government and institutional land-uses has increased development density and removed existing greenery and planting spaces. Road construction and improvement has widely damaged roadside trees and removed valuable and conspicuous greenery. Proliferation of underground utilities has fuelled the contest for usable space and precluded planting in many places. Widespread and frequent roadside trenching, associated with utilities and the laying of cable television and telecommunication networks has incurred massive root damage at roadsides. Poor soil quality commonly beset by chemical and physical constraints has caused chronic poor tree performance. Intrusion into urban parks and other green enclaves by buildings and roads has usurped the limited stock of green spaces. Encroachment into peri-urban woodlands has deprived the city of fringing mature greenery with conservation, landscape and amenity worth. Plantable space in reclaimed lands has been intensively used with inadequate allocation for trees. Protection and preservation of champion specimens has lacked statutory means and a coordinated policy. Reinforcement and demolition of stone walls has destroyed many large trees on unique mural habitats. Quality of arboricultural practice is poor, particularly in the private sector. Possible solutions to these limitations in Hong Kong are suggested, and have implications for other cities facing similar problems. Environmental Conservation 25 (2): 146-159 © 1998 Foundation for Environmental Conservation Urbanization impacts on trees 147 Figure 1 Urban areas in Hong Kong are characterized by a maximum use of developable land, often with 100% impervious site coverage and absence of setback at road frontage, thus precluding the planting of intra-and peri-site trees.

Effect of soil sealing on the microbial biomass, N transformation and related enzyme activities at various depths of soils in urban area of Beijing, China

“…However, urban soil sealing alternated the biotic and abiotic factors that regulating N transformation and seriously affected soil N pool and flux (Lorenz and Lal 2009). This, in turn, would influence nutrient availability of soil organisms and roadside tree growth (Jim 1987(Jim , 1998Scharenbroch et al 2005). Moreover, researchers suggest that leaching of excessive inorganic nitrogen is the main factor that causes urban groundwater pollution and affects human health (Fleige et al 1980;Mitchell et al 2005).…”

Community attachment and resident attitude toward old masonry walls and associated trees in urban Hong Kong

“…Rapid urbanization since the Second World War fuelled production and consumption of developable land, which is increasingly expensive (Chiu, 2006;Jim, 1998a). Some of the urban Districts have been filled to over 45,000 persons/km 2 (i.e.…”

“…They include the walls of historical buildings, geotechnical retaining structures, and ruins of monuments. In Hong Kong, old masonry walls are concentrated in the urban core developed in the nineteenth and early twentieth century, notably the northern strip of Hong Kong Island and the Kowloon Peninsula (Jim, 1998a(Jim, , 1998b. Some are situated at roadsides and adjacent to main streets, while others are found in obscure lanes and behind buildings.…”

“…Urban trees contribute to the well-being of people, environmental quality, and the long-term sustainability of cities (Beer, Delshammar, & Schildwacht, 2003;Chiesura, 2004;Jim, 1998aJim, , 2003Konijnendijk, 2008;Miller, 1997). Yet the term 'urban tree' carry ambivalent or incongruous undertones.…”

Using a Spatial Interaction Model to Assess the Accessibility of District Parks in Hong Kong

“…Accessibility to green spaces are especially important for residents of the extremely compact city of Hong Kong because of the highly congested urban environment, with numerous skyscrapers and inordinately stressful daily living. The vicissitudes of UGS in Hong Kong reflect the universal phenomenon of intensive conflict between natural and artificial components in cities, calling for smart landscape planning and management to find better solutions [3]. An optimal spatial pattern of parks that can serve most residents satisfactorily in terms of accessibility and quality of recreational experience can fulfil a key quest of a sustainable city.…”