ENG-1976 — Page 289

NATURAL HISTORY

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Finless Porpoise (Neophocaena phocaenoides) and the Chinese White Dolphin (Sotalia chinensis).

Since its introduction more than 100 years ago, the Japanese Oyster (Crassostrea gigas) has been successfully established in Deep Bay, where it is now commercially cultivated.

The freshwater fauna of Hong Kong is relatively poor in variety compared with that of South China. This probably results from the absence of a perpetual system of rivers and lakes. Although there are large quantities of water stored in man-made reservoirs, only a few varieties of fish life have been introduced-primarily for water quality control purposes. The indigenous fauna comprises only limited species of cyprinid, loach and goby. The African Tilapia has established itself in local waters but its initial introduction cannot be traced. Hong Kong now has some 3,500 acres of commercial fish ponds, where the Grey Mullet and seven species of Chinese carp are being produced at a rate of 1.2 tons per acre a year.

Flora

For so small an area, Hong Kong has a large and diverse flora of vascular plants. It is estimated that there are about 2,500 species, native and introduced. The territory is situated near the northern limit of distribution of tropical Asian flora, and the Check List of Species lists a number of plants which are more commonly found in the tropical forest than in the typical Hong Kong vegetation of today.

Before conservation, countless hillsides had been left bare of all trees through centuries of cutting, burning, and exposure to the elements. Their only cover was grassland or scrubland with patches of coarse grass. But now many slopes-partic- ularly those in the water catchment areas-have been replanted with trees of both local and exotic species. These woodlands, and other areas of countryside, are protected and are being developed for the ever increasing numbers of people who spend their leisure time in the country.

Remnants of bygone forests-either as scrub forest or as well developed woodland -occasionally persist in the steep ravines. These have survived the destructive in- fluences of man and fire by their precipitous topography and their moist winter microclimate. It is in such places that many of the more interesting plants occur. There are also small areas of well grown woodlands near the older villages and temples. These fung shui groves, 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 occasionally occurs. Also, on sandy beaches, there are patches of vegetation which are peculiar to these sites. These two vegetation types are particularly well adapted to their environment, providing a useful educational example.

Many species of plants in Hong Kong are noteworthy for the beauty or fragrance of their blossom. They also attract butterflies and other insects, while other plants bear fruits and seeds which are important sources of food for birds and animals.