Hong Kong and Victoria Habour in 1820

Hong Kong and Victoria Habour nowadays

Human ImpactsTemporal disturbance (e.g., noise)

Direct attack to species (e.g., hunting, deforestation)

Disturbance to the ecosystem (e.g., pollution, deforestation, hill fire)

Destruction of the ecosystem (e.g., change of land use, reclamation)

>>> degree, scale, rate?

Can we restore what we destructed?

2 case studies Deforestation and plantation

River and channelization

Learn from the past, and cast light on the future

Deforestation and Plantation

Hong Kong before 1840sMan has lived in this place for >5000 yrs. It is

believed that the destruction was very limited at that time.

Before 1500 A.D., the population was still very spared. Then it increased very rapidly and it reached 50000 by 1840s.

City government planted Ficus microcarpa ( 细叶榕 ) for the purposes of greening and city beautification.

 

“Bay and Island of Hong Kong” (1838) by Auguste Borget

细叶榕 (Ficus microcarpa)

Hong Kong in the Imperial AgeSystematic plantation started in 1870s, Pinus

massoniana ( 马尾松 ) was the only successful species because of the infertile soils of HK.

In 1880s, the government annually planted >100,000 siblings. Exotic species was introduced experimentally from Australia:

Eucalyptus citriodora ( 柠檬桉 ) Eucalyptus robusta ( 大叶桉 ) Eucalyptus tereticornis ( 细叶桉 ) Lophostemon confertus ( 红胶木 )

Deforestation had temporarily occurred when New Territories was rent to British in 1898.

Hong Kong in the early 20th centuryMore exotic species were introduced. Among

them, 台湾相思 (Acacia confusa) and 银合欢(Leucaena leucocephala) were two more successful species. They can: Survive in dry/harsh environment Growing fast Naturalize Fix nitrogen

Commercial forestry was an important commercial sector. By 1930s, plantation extended from lowlands up to the elevation of 250m.

WWII and DeforestationDuring the war time, large areas of woodland were

logged down due to: The surge of refugee Stop supply of firewood from China

In 1953, the government launched a new forestry policy and >100,000 siblings were planted annually. More exotic species were introduced from other countries. Pinus elliottii ( 爱氏松 ) was one of the more successful species.

 

Tai Lam Chung in the 1950s

 

Tai Lam Chung nowadays

 

Plantation crew in the old days

The Birth of Environ. Forestry in 60sCommercial forestry collapsed due to rapidly

declining demand for firewood after late 1950s.

In 1965, AFD stated that the objectives of plantation were: Soil conservation Ecological conservation Outdoor recreation

AFD also sought the possibility of establishing country parks in Hong Kong.

Country Park and Plantation in 70sThe enactment of the Country Park Ordinance in 19

76 ultimately elimination the problem of illegal logging. The key tasks left were hillfire prevention and ecological restoration.

In order to maximize the vegetation coverage in a very short time, monoculture was common.

The outbreaks of pests terminated the use of Pinus massoniana ( 马尾松 ) and exotic species became the main force of the plantation efforts.

 

Country Parks are the venues for plantation.

  Exotic speciesgrow fast.

Plantation (1980s-now)Mixed culture and native (broad leaf) species

were included in the plantation program because of aesthetical and ecological reasons.

In the recent years, >500 thousand siblings are planted annually. Among these, about 59% are native species.

 

 

Public participation

Issue I: species selectionThe plantation recipe is simple. A small

number of species are generally included.The plantation program heavily relies on

exotic species. Among of them, Lophostemon confertus ( 红胶木 ), Acacia confusa ( 台湾相思 ) and Acacia auriculiformis ( 耳果相思 ) are the most important ones.

The following lists the “Top Ten” species. They represent about 40% of the plantation efforts.

红胶木 (Lophostemon confertus) 台湾相思 (Acacia confusa) 耳果相思 (Acacia auriculiformis) 裂斗锥栗 (Castanopsis fissa) 毛叶桉 (Eucalyptus torelliana) 木麻黄 (Casuarina equisetifolia) 枫香 (Liquidambar formosana) 短花楠 (Machilus brevifolia) 爱氏松 (Pinus elliottii) 白千层 (Melaeuca quinquenervia)

The canopy of exotic species is spare

Issue II: restoration

What does “restoration” refer to?Both exotic and native species have their

own strengths and limitations. How to balance?

How about fauna?

Pros Cons

1. Harshness tolerable

2. Fast growing

3. Commercial available seeds

4. “Pest free”

5. May not naturalize

1. Not fit local ecology

2. Shallow roots

Exotic species: pros and cons

 

The survival rate of native species is low. Even through it survives, its growth may be stunted due to the harshness of the environment.

River and Channelization

Channelization History of Hong Kong ~1960 Under Public Works Department, Drainage Works Offi

ce designed, constructed and maintained drainage and channels. 1964-67 Roads and Drainage Section formed, in charge of Yue

n Long Flood Control Scheme （元朗防洪計劃） , successfully solve the local flooding problem.

1967 Sewage and Drainage Advisory Group （ later changed to Drainage Works Division ） formed, strategically investigated the possibility of flooding prevention.

1969-76 Shing Mun River Flood Control Scheme （城門河防洪計劃） , matched the development of Shatin New Town.

Late 70’s to present Channelization is considered as a component of infrastructure.

Late 80’s The issue of flooding re-appeared in NT

Channelization History (cont’d)

1989 Drainage Works Division upgraded to Drainage Works Department.

1990 Issued Territorial Land Drainage & Flood Control Strategy Study （全港排水及防洪戰略報告）。

1994 Passed the land Drainage Ordinance. 1995-2001 Main Drainage Works (MDW, 元朗區、錦田

區、粉嶺區和上水區內的主要河道排水系統工程） . 1995-2004 Shenzhen River Flood Control Scheme （深

圳河防洪計劃） . 1997-2001 Rural Drainage Rehabilitation Scheme (RDRS,

鄉郊排水系統復修計劃） .

Spatial Extent of Channizalization in HK

No official data availableFrom piecemeal data from annual reports

of Drainage Services Department and formerly Public Works Department, it seems likely that channelization is quite extensively widespread in Hong Kong.

Nevertheless, more channelization works will be done in next 10 years.

Major channelization projects in Hong Kong

Environmental friendly design Channel

Unlined channel Grass-grid Man-made point bar Fish ladder?

Riparian zone Abandoned meander Landscaping

http://www.epd.gov.hk/epd/english/environmentinhk/eia_planning/guide_ref/drainage2.html

Questions to askAgain, what does “restoration” refer to?The strengths and limitations of these

designs?Rooms for improvement?

Restoration Plan

22 Feb 04

1 Apr 04

27 May 04

Hell (Before Restoration)?

Heaven (After Restoration)?

Further questions to ask

Do you think the restoration is successful?What are the shortfalls?What are the necessary and sufficient

factors for success?

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