SECTION 4 ECOLOGICAL RESOURCES CAPITAL STOCK
4.3 Impacts and Resource Constraints for Terrestrial and Marine Habitats and Species
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| 4.3.2.9 |
Other damage and disturbance to terrestrial habitats may occur through littering, poaching/trapping, trampling, and introduction of exotic (ie non-native) species. Littering and other illegal disposal of waste not only degrades the visual landscape but also may have ecological effects on the natural community. Refuse can interfere with normal usage of the habitat for nesting and feeding, attract scavenging species such as cockroaches, rats or crows to the area and displace native species, and can introduce pollutants to vegetation, soils and even the biological food chain. The use of land for unauthorised waste disposal is discussed in greater detail in Paragraph 3.2.2.10 - Land Use and Land Supply. |
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| 4.3.2.10 |
Poaching, trapping, hunting and collection of commercially valuable species is also a threat to the maintenance of Hong Kong's ecological communities. Several species of rare plant are collected for their herbal/medicinal value (eg orchids, Pitcher's Plant and Chinese New Year Flower) and a number of animal species including some birds, butterflies, dragonflies and newts are gathered for sale to collectors or pet shops (WWF 1999). The media periodically reports incidents of illegal capture of wild animals, particularly the poaching of waterfowl in and around Deep Bay. However, no statistics are available to address whether such activities are increasing or decreasing with time. |
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| 4.3.2.11 |
It is also difficult to assess the effects of human disturbance associated with recreational use of terrestrial habitats. Activities such as hiking, camping, outdoor war games and orienteering can result in the trampling of vegetation, disturbance of sensitive habitats such as wetlands or streams, and injury or stress to nesting birds or foraging mammals. These activities may have a minor impact in comparison to other impacts discussed above such as development and hill fires. Nevertheless recreational usage of the Country Parks which contain some of Hong Kong's most ecologically valuable habitat is likely to increase with the growing population, and its increasing interest in outdoor recreational opportunities, and thus in total exert a noteworthy impact. |
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| 4.3.2.12 |
Finally, the intentional or inadvertent introduction of exotic species can have substantial impacts on native species, and perhaps even the structure of the ecosystem. For example, floating plants such as the water hyacinth (Eichhornia crassipes), which originates from Brazil, can cover the surface of freshwaters resulting in reduced light penetration which inhibits the development of submerged plants and restricts gaseous exchange between water and air. Non-native plant or animal species which are released to the wild and establish viable populations, can threaten existing species through competition and predation. If it cannot adapt to resist the exotic invader, the native species may decline or disappear, thereby reducing biodiversity and potentially triggering additional changes in ecosystem structure. Examples of exotic species introduced to Hong Kong are manifold and include (Dudgeon and Corlett 1994):
- the pinewood nematode (Bursaphelenchus xylophilus) which causes the lethal pine wilt disease and has virtually eliminated the native pine species (Pinus massoniana);
- the honey bee, Apis mellifera, which originated in Europe, appears to have largely displaced the native Asian hive bee (Apis cerana); and
- the terrestrial mollusc, Incilaria bilineate, is a slug which has become a minor agricultural pest.
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