Urban Ecology

1. Planning and Distribution of Habitats in Kwai Chung

The urban greening works of Kwai Chung began with the development of Tsuen Wan New Town development in the 1970s. Together with the need to increase Hong Kong’s competitiveness through developing a cargo industry, the government places residential and cargo usage as the priority in the planning of Kwai Chung. There is also a lack of an overall greening framework, which was introduced in the Greening Master Plan until 2010, and the green open spaces in the site are mainly served for visual pleasure, instead of wildlife habitats. As an adaptation to such urban settings, the ecological communities not only live in green areas, but also transport facilities like outdoor car parks and typhoon shelter.

2. Types of Ecological Communities

2.1. Hierarchy in the Food Web

Limited by the small and fragmented green spaces in the site, the wildlife has low mobility to move from one habitat to another and the diversity of the species are relatively low. Moreover, the small variations in the type of habitats are unable to support the specific needs of rare wildlife species. As a result, the structure of the food web is simple and supported by common suburban species.

2.2. Ecological Communities Recorded

Due to the complex road networks and the priority of residential and industrial activities in urban planning, the habitat available for organisms are fragmented and the plant communities are affected by the changes in environment (Greening, Landscape, and Tree Management Section, 2020). Only common suburban species, including both animals and plants, are able to adapt to the built environment with busy human activities. No species of conservation interest are found during the survey.

Distribution of the Bird Communities in the Site
Distribution of the Butterfly and Insects Communities in the Site
Distribution of the Stray Animal Communities in the Site

3. Conflicts between the Users and the Ecological Communities

3.1. Impacts of the User Activities on the Ecosystem and the Animal Behaviours

3.1.1. Disturbance on Bird Behaviours by Illegal Dumping

As the natural habitats are closely surrounded by residential, commercial and industrial areas, the problem of illegal dumping influences the bird behaviours and the food chains. The birds no longer search for food from nature and rely on food waste instead. This harms the health of the wildlife and disturbs the balance of the food chains.

3.1.2. Degradation of Water Quality in the Rambler Channel

The mismatched drainage is also another serious issue that affects the health of the wildlife. The drainage system in Kwai Chung has not changed since the 1970s. According to the report of the Environmental Protection Department (2010), there are 52 sewage and stormwater drainage mismatch cases in Kwai Chung. Coupled with the problem of illegal drainage, the outdated drainage system releases untreated sewage in Rambler Channel and leads to serious water pollution that degrades the Egret habitats, as well as the marine resources. Moreover, due to the absence of freshwater resources in the site, the wildlife often drink the polluted water from the drainage in industrial and commercial areas, harming their health and encouraging the spread of diseases in the ecological communities.

3.1.3. Oil Leakage in the Rambler Channel

According to the regulations of the Marine Department, ship owners can enter and park their ships any time based on their operational needs without any time restrictions. As a result, some owners park their ships there for a long time to save the cost of renting a private parking space and issues like oil leakage are not identified quickly. Together with the drainage problem mentioned above, the water quality in the Rambler Channel is degraded by the oil leakage. As the waterbird communities live on the breakwater, they are heavily influenced by the poor water quality and polluted marine resources.

3.2. Impacts of the Ecological Communities on the Living of the Users

3.2.1. Rodent and Mosquito Problem

Although the problems of illegal dumping, improper management of refuse collection points and the mismatched sewage and stormwater drainage harms the health of the wildlife, they encourage the growth of the rodent and mosquito communities in Kwai Chung with abundant food waste and water resources. The statistics of the Food and Environmental Hygiene Department (2020) shows that both the rodent and mosquito communities have an increasing trend in their population. Thus, it is essential to review the management of waste disposal and the outdated drainage system to control the pest problem.

Monthly Ovitrap Index for Aedes albopictus of March 2020








Kwai Chung

AGI (Area Gravidtrap Index for Aedes albopictus)






ADI (Area Density Index for Aedes albopictus)






Lai King

AGI (Area Gravidtrap Index for Aedes albopictus)






ADI (Area Density Index for Aedes albopictus)






Monthly Ovitrap Index for Aedes albopictus from April, 2020 to August, 2020


Gravidtrap Index for Aedes albopictus


G.I. < 5%


5% ≤ G.I. < 20%


20% ≤ G.I. < 40%


G.I. ≥ 40%

Gravidtrap Index for Aedes albopictus
Rodent Infestation Rate from 2009 to 2019
Rodent Infestation Rate of All Districts in 2020


Rodent Infestation Rate




Rodent infestation is not extensive in the area


10% – 19%

Rodent infestation is slightly extensive in the area



Rodent infestation is extensive

Levels and Indication of Rodent Infestation Rate in Hong Kong

4. Opportunities and Constraints

There are opportunities of utilizing the unused spaces as green infrastructures and reconnecting habitat patches to reduce the space competition between residents and wildlife. Another opportunity would be to review the outdated drainage system to control the water pollution that degrades the egret habitats and water sources for wildlife. However, the complex land ownership, economic cost and the management method may be the main constraints.

Census and Statistics Department. (2020). Hong Kong Monthly Digest of Statistics October 2020. Hong Kong: Census and Statistics Department.

Environmental Protection Department. (2010). Agreement No. CE 37/2006 (DS): Review of West Kowloon and Tsuen Wan Sewerage Master Plans : Feasibility Study. Retrieved from https://www.epd.gov.hk/epd/sites/default/files/epd/english/environmentinhk/water/studyrpts/files/TWWK_ES_ENG.pdf

Food and Environmental Hygiene Department. (2020). Dengue Fever Gravidtrap Index Update. Retrieved from https://www.fehd.gov.hk/english/pestcontrol/dengue_fever/ovitrap_index.html

Planning Department. (2016). Environmental Protection and Nature Conservation for Sustainable Growth. Retrieved from https://www.hk2030plus.hk/document/Environmental%20Protection%20and%20Nature%20Conservation_Eng.pdf

The Greening, Landscape, and Tree Management Section, Development Bureau. (2020). Street Tree Selection Guide. Retrieved from https://www.greening.gov.hk/filemanager/content/pdf/knowledge_database/street_tree_selection_replacement_guide/Full_report.pdf

Threlfall, C.G., Ossola, A., Hahs, A.K., Williams, N., Lee, W., & Livesley, S. (2016). Variation in Vegetation Structure and Composition across Urban Green Space Types. Ecology and Evolution, 4, 1-12.