ENG-1982 — Page 325

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NATURAL HISTORY

propagation and nursery grounds for many species of fish, crustacea and molluscs, and provide seasonal feeding for large transient predators, such as the Little Tuna, Dolphinfish, Sailfish and sharks.

More than 20 species of shark have been recorded in Hong Kong waters, mainly in the eastern and southeastern areas. Sharks have been sighted in Mirs Bay in the New Territories and as far south as Stanley and Deep Water Bay on Hong Kong Island. Their presence in Hong Kong is a result of the influence of warm ocean currents off the South China Sea during the summer months, in particular, July to September. Sharks which are common in Hong Kong and potentially dangerous are the Hammerhead Shark and species of the True Shark family, which can grow to more than three metres. Other commonly- found sharks which do not normally attack humans include the Cat Shark and the Leopard Shark.

During February and March 1982, three species of marine mammals were recorded in Hong Kong waters: a young Lesser Rorqual whale was found stranded on a beach east of Tai Po; a black finless porpoise was washed-up at Shek O; and a rough-toothed dolphin was found dead on Sharp Island. Dead specimens of the same species of whale and porpoise were also recorded during these months in 1978.

Flora

The Hong Kong Herbarium, which contains about 34 000 plant specimens, is more than 100 years old. This government institution, administered by the Agriculture and Fisheries Department, is responsible for collecting, classifying and maintaining authori- tative preserved plant specimens representative of Hong Kong flora. It also disseminates knowledge and information by maintaining an index of scientific, Chinese and English common names for the plants of Hong Kong. The herbarium, housed in the New World Centre Office Building in Tsim Sha Tsui, is open to the public.

Situated near the northern limit of the distribution of tropical Asian flora, the plants of Hong Kong are large in number and variety. It is estimated there are about 2 600 species of vascular plants, both native and introduced, and these are listed in the Check List of Hong Kong Plants (Agriculture and Fisheries Department).

Before the introduction of conservation measures, the hillsides were becoming in- creasingly bare of trees as a result of cutting, burning and exposure to the elements. On most, the only cover was coarse grass or scrub. Now many slopes, particularly those in the water catchment areas, have been planted with trees of both local and exotic species. These woodlands, and other areas of countryside, are protected and are being developed for the growing numbers of people who spend increasing amounts of their leisure time in the countryside.

Remnants of the original forest cover - either scrub forest or well-developed woodlands - are still to be found in steep ravines. These have survived the destructive influences of man and fire through their precipitous topography and moist winter microclimate. It is in such places that many of the more interesting plants grow. Small areas of well-grown woodlands can also be found near the older villages and temples. These fung shui, or sacred groves owe their existence to the protection afforded by generations of villagers in accordance with ancient tradition.

On muddy sea shores, an interesting type of vegetation known as the Dwarf Mangrove Association is occasionally found; there are also patches of vegetation peculiar to sandy beaches. These two vegetation types are particularly well adapted to their environment – providing a useful educational example.