生境破壞 Habitat Destruction
Hong Kong possesses various types of habitats for many different species to live in. However, when these habitats are degraded or destroyed, they can no longer support the organisms living there. This will result in the loss of species, or even extinction of endemic species. In other words, there will be a decrease in biodiversity.
Habitat destruction can be caused by natural or anthropogenic (human-related) factors. Natural causes include hill fires, volcanic activities and climate change, while human causes include urban development, clearing land for agriculture, construction of infrastructure, etc. As urban and rural areas exist shoulder to shoulder in Hong Kong, human activities plays an even more important role in habitat destruction.
1. Urban expansion
Hong Kong has seen rapid urban expansion in recent years resulted from new town and New Territories Small House development. When natural areas are transformed into urban areas, habitats like woodland and wetlands will be replaced by flat ground with buildings (Fig. 1). This takes away the natural shelters of many organisms such as birds and fish.
Other than residential use, some habitats will also be exploited for business or entertainment uses, such as to establish open cargo storage (Fig. 2) resorts and golf courses (Fig. 3).
Not only does urban expansion directly destroy habitats, it also speeds up erosion, which leads to soil degradation. Since vegetation in the area is removed (Fig. 4, 5) and the natural drainage is altered, excess water in the soil cannot be cleared away. Moreover, a layer of concrete covering the topsoil makes is difficult for rainwater to be drained away. These add up to result in easier erosion of soil by water. Besides that, without the protection of plants, the soil is more vulnerable to erosion by wind as well. Eventually, the soil in both the developed area and neighbouring areas would become poor, and habitat deterioration is made more severe.
Other than the above-mentioned, construction work also causes various pollutions such as water, air and soil pollution. Upon completing construction, the subsequent anthropogenic activities will bring noise pollution too. This may force organisms that require a quiet living environment, such as birds, to move and seek shelter elsewhere.
2. Building infrastructures
The Hong Kong government launched the Ten Major Infrastructure Projects in 2007. The Projects include the MTR Shatin to Central Link, the Hong Kong-Zhuhai-Macau Bridge, the North East New Territories New Development Areas, etc. However, when carrying out these projects, habitat destruction is also brought about.
One of the Projects is the Hong Kong-Zhuhai-Macau Bridge, situated along the coast outside Tung Chung. As part of the Bridge involves a sea viaduct, piers have to be built by digging into the seabed (Fig. 6), which causes the loss of shelter of seabed organisms. Also, sand and mud will be stirred up during the construction. There are also incidents, in which a sand barge was suspected to have leaked sand into the water, bringing further harm to the marine environment (Fig. 7). After construction, the increased freight and ferry traffic may further disturb nearby waters or even threatens the life of marine organisms there.
Other than the Ten Major Infrastructure Projects, other transportation structures such as roads will also find their way into rural areas following urban development. This may result in habitat fragmentation, in which natural resources are divided into smaller portions (Fig. 8), making it more difficult for organisms to survive.
3. Illegal waste material disposal
In 2005, the Construction Waste Disposal Charging Scheme became effective. To avoid paying for the waste, some workers would dump waste materials in the countryside after the construction (Fig. 9 and 10). Some of the waste may release toxins, which seep into the land and underground water, or directly enter ponds and lakes, polluting the aquatic habitats.
Human activities may unknowingly damage natural habitats, leading to the loss of beautiful natural scenery. More importantly, it also causes the loss of species, some of which are beneficial to us. Therefore, when carrying out city development, we should also consider how to achieve a balance between development and conservation, and how to protect the Hong Kong’s precious species and natural habitats.