Mangrove forests are scarcely distributed throughout Hong Kong because of the cold winter and few protected muddy bays.

The distribution is also limited by human activities, such as reclamations and coastal development. There are just 44 mangrove stands still remaining in Hong Kong, covering an area of around 290 hectares. They are found in Deep Bay, with Mai Po having the largest and best known in Hong Kong.

Mangroves on Lantau Island can be found in Tung Chung, Tai O and Shui Hau. Whereas Kai Ling Ha Lo Wai, Pak Sha Wan, Nai Chung, Hoi Ha Wan are other areas in the Sai Kung region.

New Territories has a few spots, too.

Mangrove forests are a group of unrelated plants found on the intertidal mudflats in the estuarine environment, influenced by regular tidal flushing from streams and rivers. The substratum where mangroves grow is highly a saline, anaerobic and mobile substratum. The mangroves also have to face periodic wet and dry environments, therefore, mangroves have some specialized and distinctive features to help themselves withstand and adapt to these unique and harsh environments. Salt glands are present in leaves of some mangrove species, to concentrate salts absorbed and actively secrete the excess salts so as to regulate the salt concentration inside the vegetation. Pneumatophores are erect aerial roots arising from cable roots to facilitate gaseous exchange of the roots in water-logged soil. Their roots also contain aerenchyma tissue to allow efficient transportation of gas. Propagules are germinated mangrove seeds still attach to the parent plant after fertilization, and they are dispensed only when they reach a highly developed state. This allows rapid growth and establishment of mangrove seedlings once they detach and reach the substratum, thus improving their survival rate in the unstable substratum and the inter-tidal environment.

Mangrove forests are so important to coastal ecosystems. They help protect the shorelines, preventing erosing by waves and wind. They also stabilize the sediments and retrain nutrients just like a natural sewage treatment system. It can maintain the balance between coast and marine ecosystem. In addition, mangrove forests provide various habitats for thousands of living creatures to inhabit, feed and breed, thus maintaining biodiversity.

Mangroves actually serve as valuable nursery areas for fish and invertebrates. It also can support threatened and endangered species at least some portion of their lives, e.g. the immigration bird. In other parts of the world, people have even utilized mangrove trees as a renewable resource in building houses, boats, pilings and furniture. Some countries in Africa even develop eco-tourism by watching wildlife. But I see mangrove forest like wetland is the best outdoor learning classroom.

(HK Edition 12/05/2008 page4)