Ecology :: Plant conservation key to ecologic balance

Flora conservation will not only protect Hong Kong’s rare plants, but is also important in maintaining the city’s ecological balance, Conservation Officer Dr Yip Kwok-leung says.

A species of the birthwort family, Aristolochiaceae is a group of attractive plants and odd-shaped flowers with small natural populations that are the larval food of certain kinds of rare butterflies. Conservation of these plants is crucial to help enhance the survival of these butterflies, Dr Yip said.

Green gift

Speaking to, Dr Yip said Hong Kong, though small in size, has flora that are diverse in character and surprisingly numerous in species.

“Over 3,100 species and varieties of vascular plants have been recorded in Hong Kong, around 2,100 of which are native and the rest are cultivated here. Under the Forests & Countryside Ordinance, plants growing on government lands are protected from exploitation. However, as some rare and attractive species are still subject to other threats which may threaten their overall survival, efforts are needed to conserve these plant species.”

Once the need for conservation has been identified, efforts will be made to conserve valuable species, including habitat protection and ex-situ conservation, which is like running a nursery where young plants and trees are grown carefully in a controlled environment.

When they have become strong enough, they will be transplanted to the natural environment. This is an expensive and a labour-intensive process, Dr Yip said, adding that only rare and endangered species requiring assistance will be selected.

Special care

Ex-situ conservation will be conducted only if plants:

* are found to be weak biologically, causing difficulties in survival with competition from other species;

* have difficulty in delivering offspring;

* have their habitats under threat, such as through fire or pollution; and,

* are subject to exploitation.

Ex-situ conservation is mainly held in Shing Mun Arboretum and Tai Tong Nursery. The former occupies four hectares of abandoned terraced fields. About 300 species including some locally and globally rare species have been propagated and established there for conservation and education purposes.

The Greenhouse of Field Investigation Unit at Tai Tong Nursery provided an excellent environment for conservation of rare and precious plants, particularly the more fragile ones. The greenhouse is equipped with automatic misting, a temperature and humidity control system as well as environmental growth chambers and a seed depository.

More than 100 species, especially the more fragile species and orchids have been conserved.

The greenhouse, operating since 2003, is the first of its kind in Hong Kong that’s dedicated to the protection of endangered indigenous plants. It is also equipped with several plant growth chambers for conducting propagation experiments on rare local plants in a controlled environment.

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