Managing urban trees and their soil envelopes in a contiguously developed city environment

Urban Hong Kong is covered by high building, road, and population densities . Its urban morphology is inherently not conducive to extensive or high-gra de greening. Recent renewal of old areas has squeezed out some limited inte rstitial plantable space, although in new development areas modest spaces h ave been earmarked for greenery, The study aims at evaluating the major con straints to urban trees and their companion urban soil envelopes and at pro viding specific recommendations to improve tree management in the city. The analysis covers the above-ground confinements that dampen tree performance , the less tangible but rather difficult institutional restrictions that im pose a somewhat unnecessary lid on tree planting, the multiplicity of playe rs and stakeholders involved in urban-tree management that militates agains t coordination and cooperation, the widespread occupation of underground sp ace by utility lines often to the exclusion of trees, and the extremely poo r quality of urban soils that are often used without amelioration to suppor t tree growth. The management recommendations furnish practical suggestions and hints to improve the short- and long-term welfare of trees in terms of quality, quantity, and spatial distribution. The conclusion enumerates som e concrete measures for consideration by decision-makers to upgrade the cit y's greenery to close the gap between science and policy.