Rare and Precious Plants of Hong Kong
Introduction
Hong Kong is situated on the
South-East coast of the Mainland China, between latitude 22º9'–22º37' north, and longitudes 113º52'–114º30' east. It consists of a small part of the Mainland
and about 235 small offshore islands, covering approximately 1100 km2.
As it is within the northern
fringe of the Tropics, the warm climate and plentiful rainfall have fostered
a luxuriant vegetation. According
to the recently-published “Checklist
of Hong Kong Plants” (Wu et al.
2001), in Hong Kong there are 3136 vascular plant species, about 2100
of which are native species and the remaining 1000 are cultivated or naturalized.
Among the native species, 219 are ferns
representing 92 genera in 45 families, 8 are gymnosperms representing 6 genera
in 5 families, and about 1900 species are flowering plants in 827 genera and
172 families. Apparently, Hong
Kong has a rich and remarkably diverse flora for its small land area.
.....Plants are primary producers on which human beings and other organisms
rely for existence. Plants provide us food, energy, shelter, clothing, medicines,
and other things essential to our daily life, not to mention the greenery,
fragrance and the diversity of colors and forms of plants, which are invaluable
assets of our nature. The Agriculture, Fisheries
and Conservation Department (AFCD) is responsible for nature conservation
in Hong Kong. The purpose of
this publication is to gather and disseminate the information about some of
our rare and precious plant species, in the hope not only to raise the awareness
of the general public about plant conservation in Hong Kong, but also to stimulate
conservationists, academics, researchers and horticulturists to make further
efforts to study and conserve our precious plants.
Definition of Rarity
The words “rare” might be interpreted differently
by different people. In general usage, it means something being widely
separated, infrequently occurred, or of unusually good quality. To biologists, ecologists and
conservationists, however, it has more restricted definitions. One could define rarity in terms of
abundance, range size, habitat specificity, temporal persistence, threat,
endemism and taxonomic distinctness. Nevertheless, the majority of biologists regard rare species
as those that are low in abundance and/or small in distribution ranges.
Theoretically, Rabinowitz (1981) proposed
a thought-provoking classification of various form of rarity based on three
attributes namely geographical range, habitat specificity and local population
size. The combinations of characteristics and patterns are summarized below:
| Geographic Range | Habitats Specificity | Population Size | Combination of Characteristics |
| Large | Wide | Small, non-dominant | Constantly sparse over a large range and in several habitats |
| Large | Narrow | Large, dominant somewhere | Locally abundant over a large range in a specific habitat |
| Large | Narrow | Small, non-dominant | Constantly sparse in a specific habitat but over a large range |
| Small | Wide | Large, dominant somewhere | Locally abundant in several habitats but restricted geographically |
| Small | Narrow | Large, dominant somewhere | Locally abundant in a specific habitat but restricted geographically |
| Small | Narrow | Small, non-dominant | Constantly sparse and geographically restricted in a specific habitat |
The
above mentioned characteristics reflect the genetic makeup of the species and
their adaptation for survival in nature. In addition to the intrinsic causes
such as inherent difficulty to regeneration, the decline of distribution range and reduction of
population size, individuals of a species are also influenced by the following
factors:
1.
Loss and degradation of habitats,
caused by development and human population increase;
2.
Over-harvesting and overexploitation;
3.
Environmental pollution; and
4.
Invasion of exotic species.
One Hundred Species of Rare
and Precious Plants in Hong Kong
In practice, the following criteria are adopted to select the 100 rare
and precious plant species in Hong Kong:
1.
Species endemic to Hong Kong;
2.
Species that are native to Hong Kong
and of national importance: including species listed in “China Plant Red Data Book”, Vol. 1 (edited by China National
Environment Protection Agency & Institute of Botany, Academia Sinica, 1992)
and the “List of Wild Plants Under State Protection” (promulgated by
the Ministry of Forestry in 1999);
3.
Species that are native to Hong Kong
and of importance in Guangdong: including the species listed in the Illustrations of Rare and Endangered Plants
in Guangdong Province (edited by Environment Protection Bureau of Guangdong
Province & South China Institute of Botany, Academia Sinica, 1988);
4.
Native species that have important
scientific interests, species that have potential value in various uses, or
species having small populations or sparse distribution in Hong Kong.
Table
1 lists the 100 rare and precious plants and the respective criteria fulfilled.
IUCN Categories and criteria
of the threatened plant species
The
International Union for Conservation of nature and Natural Resources (IUCN)
Red List Categories and Criteria have been used for assigning threat status
in red data books and red lists worldwide.
In version 3.1 (2001), seven threat categories are recognized: Extinct
(EX), Extinct in the wild (EW), Critically Endangered (CR), Endangered (EN),
Vulnerable (VU), Near Threatened (NT), and Least Concern (LC). The definitions of the categories are
summarized in Appendix
1.
The IUCN criteria have, however, been designed
for global application and for a wide range of organisms. Hong Kong has only
a small land area of approximately 1100 km2, and belong to the
same floristic area as South China. Therefore, when evaluating the status
of a certain species using the IUCN Categories, it is necessary to take its
distribution in China as a whole into consideration. The preliminary assessments
for the status of the status of the 100 species in China are provided in this
book for reference.
Conservation of Rare Plants
in Hong Kong
Plant
conservation work in Hong Kong during the early twentieth century was primarily
focused on afforestation for soil erosion control. In recent decades, the attention
has shifted to habitat conservation and enhancement, fighting against hill fire
and enforcement on illegal felling of tree and exploitation of valuable plant
species. The
following measures taken by the government are significant to the conservation of rare and precious plant species:
Habitat Protection:
Since late 1970s, twenty-three Country Parks and fifteen Special Areas have
been designated under the Country Parks Ordinance (Cap. 208) covering 38%
of the total land area of Hong Kong. AFCD manages these areas for nature conservation,
outdoor recreation, tourism, countryside education and scientific studies.
A large number of rare plant populations in Hong Kong are located within country
parks, which are under statutory protection. In addition to the Country Parks,
there are now 64 Sites of Special
Scientific Interests (SSSIs), of which
most are established
owing to their floristic importance, so that
the rare and precious plants could be protected from land use planning perspective.
Species Protection
and Legislation: Under the Forests and Countryside Ordinance
(Cap. 96), damaging any plant in forests or plantations on government land
is strictly prohibited. In addition, a total of 27 kinds of plants, including
all tree ferns, orchids, and some rare and attractive plants such as Camellia species, Enkianthus quinqueflorus,
Impatiens hongkongensis and Iris speculatrix, have been specifically listed in the Forestry Regulations, subsidiary
legislation of Cap. 96, to control their sale or possession (See Appendix
2). Some native plants of
Hong Kong are also protected by the Animals and Plants (Protection of Endangered
Species) Ordinance (Cap. 187), which controls the import, export and possession
of the endangered plants listed in the schedules (See Appendix
3).
Ex-situ conservation and
Active Propagation: To supplement habitat protection,
AFCD has set up the Shing
Mun Arboretum for ex-situ conservation. About 300
species including
some rare and representative species have been established there. In addition, AFCD has
propagated rare plants through various methods, such as seed collection, cutting
and air layering. The seedlings
are produced with special care and subsequently
reintroduced to the wild at suitable habitats. Successful examples
of propagation
include Keteleeria fortunei, Camellia crapnelliana and Camellia granthamiana.
Plant conservation is a long-term task with strategic significance.
It is important for conservation of biodiversity and maintenance of a balanced
ecosystem. In addition to the above measures, there is still research work
to be carried out. For instance,
the ecology and reproductive biology of certain rare plant species could be
further studied whereas advanced techniques on propagation of rare plants
could be explored. These important
tasks would not succeed without the support of local academics and scientific
researchers.
The Purpose and Application of this publication
The primary aim of
this publication is to arouse public awareness on conservation of rare and
precious plant species. The 100
selected species in this publication are provided as a focal point to help
readers appreciate the conservation of our precious plant resources in Hong
Kong. However, the 100 species
should not be regarded as an exhaustive list of rare plants in Hong Kong. Furthermore,
it does not imply that any species not on the list could be damaged or
collected without deliberation. As
a matter of fact, we should try to care and appreciate every species in our
nature, no matter it is rare or not.