Rehabilitation and development of forest on degraded hills of Hong Kong

Abstract

Hong Kong's potential climax vegetation is subtropical evergreen monsoon forest but all of the original forest has been cleared by centuries of human activities. Rehabilitation of forest in Hong Kong was started as early as 1880, but all the early plantations were destroyed during the Japanese Occupation between 1942 and 1945. Most of the existing forest has developed since 1945, through either natural succession or afforestation on degraded areas protected from fire and other disturbance. Currently 14% of the land area is covered in forest comprising two-thirds of this natural secondary forest and one-third plantations. These forests play an important role in conservation and environmental maintenance. Surveys of Hong Kong's forests were carried out between 1989 and 1996 to investigate their successional status and floristic diversity. The study indicated that natural succession was the major process for forest restoration on degraded lands in Hong Kong. In the absence of fire and other disturbances, all the degraded lands could potentially be restored to closed secondary forest in 30–40 years. Afforestation can facilitate forest formation, but the ecological function of most plantations was generally weak because most planted species were fast-growing exotics. However, floristic diversity of plantations increased with age by the invasion and establishment of native species. Fire was the major limiting factor for the development of secondary forest and plantations. Forest rehabilitation on degraded areas can be greatly accelerated if fires are efficiently controlled.