Eco-Landscape Design in Urban Context Dr. Hau Chi Hang, Billy Dr. Pang Chun Chiu The University of Hong Kong
Introduction Habitat fragmentation, isolation and degradation are world-wide issue for developed countries and cities. Huge effort is spent by governments for restoring ecosystem functions, including those in urban areas. Pledged to introduce the Convention on Biological Diversity (CBD) to HK, the Government aims to promote urban biodiversity as one of the key action areas in protecting Hong Kong’s biodiversity
Case studies: New South Wales, Australia Some of the objectives: Improve the ecological health of urban riparian lands and bush lands including ecologically endangered communities; reduce weeds; increase in area and quality of native vegetation; erosion remediation; and improve habitat linkages at landscape scale. Increase long-term participation in urban ecosystem rehabilitation specifically targeting community volunteerism and investment from private and government sources. http://www.lgnsw.org.au/files/imce-uploads/35/high_country_urban_biodiversity.pdf
Case studies: Missouri, USA http://www.missouribotanicalgarden.org/sustainability/sustainability/biodiversecity-st.-louis.aspx
Case studies: Hong Kong CLP Creates Hong Kong’s Largest Sky Woodland to Promote Green Rooftops The rooftops of the two substation blocks cover area of 520 m 2 . 80 trees of 32 native species were planted since May 2013. The woodland was reported to attract an abundance of birds and insects. Source: https://www.clpgroup.com/en/Media-Resources- site/Current%20Releases/20150914_en.pdf
Case studies: Hong Kong Zero Carbon Building (ZCB) is an urban native woodland initiated by Construction Industry Council. The woodland covers an area of 2,000 m 2 , 13% of the ZCB site area. 220 trees of 40 native species were planted. The species are chosen based on four criteria: (1) Species diversity; (2) Diversity of tree form; (3) Food and shelter for wildlife; (4) Ornamental value. Source: http://www.cic.hk/eng/main/zcb/ZCB_e xperience/urban_native_woodland/
An ecological approach to upgrade DSD’s facilities The Drainage Services Department (DSD) has hundreds of facilities e.g. STP, pump houses, all over Hong Kong for providing drainage services to the public. These facilities vary in size and age, and are mostly geographically close to natural hillsides. A strategic urban biodiversity rehabilitation plan for DSD’s facilities and a practical design and management guideline on enhancing ecological value in landscaping for DSD’s facilities have been proposed.
An ecological approach to upgrade DSD’s facilities: Project Design 1. Evaluate the potential ecological value of infrastructure sites for eco-landscape design 2. Recommend design and management approach on sites identified as suitable for eco-landscape design 3. Conduct site trials in selected DSD’s facilities 4. Conduct baseline ecological study to confirm the effectiveness of eco-landscape design
Selection of Sites for Eco-Landscape Design Two main principles are recommended for selecting facilities for applying eco-landscape design: A. Establishment of a series of ecological stepping stones; B. Upgrading facilities with the greatest potential for benefiting wildlife.
A. Establishment of a series of ecological stepping stones
B. Upgrading facilities with the greatest potential for benefiting wildlife Five criteria was used for evaluating the potential of applying the Eco-Landscape Design: 1. Habitat connectivity to the natural habitats 2. Site area First stage assessment 3. Site age 4. Coverage of greenery area of the facilities 5. Existing vegetation in the Second stage assessment facilities
B. Upgrading facilities with the greatest potential for benefiting wildlife First stage assessment • Desktop review of the surrounding environment and site properties of facilities. • A total of over 70 facilities were evaluated.
First stage assessment Criteria Criteria Evaluation items Categories Score (1) Habitat (i) Distance to the nearest natural (a) Right next to a natural woodland 3 connectivity vegetation (b) Right next to a natural shrubland 2 (c) There is a natural woodland or shrubland within 1 km 1 (ii) Surrounding habitat complexity (a) Right next to streams / rivers/ woodlands / 3 shrublands / wetlands and/ or coast (a) There are green or blue corridors e.g. landscaped 2 slopes or river channels, linking to streams / woodlands / shrublands / wetlands within 1 km (c) Right next to urban forests in parks, gardens or large 1 man-made green slopes (iii) Degree of anthropogenic (a) Facilities are entirely surrounded by concretes and -1 disturbance isolated from natural or urban vegetation (2) Site area (a) Site area ≥ 2700 m 2 3 (d) Site area ≥ 540 and < 2700 m 2 0 (f) Site area < 540 m 2 -3 (3) Site age (a) Age ≥ 20 years 3 (b) Age ≥ 10 and < 20 years 2 (c) Age < 10 years 1 (4) Coverage of (a) Greenery area coverage > 40 % 4 greenery area (b) Greenery area coverage ≥ 20 and < 40% 2 (c) Greenery area coverage < 20% 0
B. Upgrading facilities with the greatest potential for benefiting wildlife Second stage assessment • On-site inspection was carried out to assess the existing vegetation of the DSD’s facilities. • Among the 70 facilities being evaluated from 1 st stage assessment, facilities having high or medium potential were visited for carrying out the 2 nd stage assessment. • Final score was formulated by: Final score = 1st stage score – 2nd stage score
Second stage assessment Criteria Criteria Evaluation items Categories Score (5) Existing (i) Total species richness (a) No. of native plant species ≥ 10 3 vegetation (b) No. of native plant species <10 0 (ii) Tree abundance (no. of (a) No. of trees ≥ 50 4 trees with dbh ≥ 95 mm) (b) No. of trees ≥ 20 and < 50 2 (c) No. of trees < 20 0 (iii) Presence of food/nectar (a) Nectar and/or fleshy fruit plants are abundant in site 2 plants in site (more than 50% of plant species provide resources to wildlife) (b) Nectar and/or fleshy fruit plants are sparse in site (Fewer 1 than 50% of plant species provide resources) (c) Absence of nectar- and/or fleshy fruit plants in site 0 (iv) Dominance of invasive (a) Dominance of invasive plants are observable. -1 and exotic plants in site (b) Site is threatened by invasive plants but not dominated. 0 (c) Absence of invasive plants 1
Evaluation Results Plant Name Coastal Wood- Rural Urban Site Area Final land (m 2 ) Score (P) 4883 15 Aberdeen PTW 64,000 13 Tai Po Sewage Treatment Works 2380 12 Sandy Bay Preliminary Treatment Works 409 12 Cyberport PTW 18,957 12 Tsing Yi Preliminary Treatment Works Kwai Chung Industrial Wastewater Pumping 6,457 11 Station 10,961 10 Sham Tseng Sewage Treatment Works 935 10 Nam Sang Wai Sewage Pumping Station 21,000 9 Sai Kung Sewage Treatment Works 271,000 8 Shatin Sewage Treatment Works 97,430 8 Stonecutters Island Sewage Treatment Works 9,440 8 Cheung Sha Wan Sewage Pumping Station 78,000 7 Yuen Long Sewage Treatment Works 89,800 7 Siu Ho Wan Sewage Treatment Works 6,490 6 Ha Tsuen No. 1 and No. 2 Sewage Pumping Station 3,301 6 Penny's Bay Sewage Pumping Station 10,734 6 San Wai Sewage Treatment Works
Selected Sites for Field Planting Trials Plant Name Site Area Final Site Context (m 2 ) Score Aberdeen Preliminary Treatment Works 4,883 15 Coastal site Tsing Yi Preliminary Treatment Works 18,957 12 Coastal and urban site Nam Sang Wai Sewage Pumping Station & Ngau 935 10 Rural site Tam Mei Main Drainage Channel Pumping Station Kwai Chung Industrial Wastewater Pumping Station 6,457 11 Urban and woodland site Tseung Kwan O Preliminary Treatment Works & 17,734 9 Urban site Pumping Station Ha Tsuen No. 1 and No. 2 Sewage Pumping Station 6,490 6 Rural and urban site
Nam Sang Wai Sewage Pumping Station (selected for site trial)
Nam Sang Wai Sewage Pumping Station (selected for site trial)
Tsing Yi Preliminary Treatment Works (selected for site trial)
Tsing Yi Preliminary Treatment Works (selected for site trial)
Ha Tsuen No. 1 and No. 2 Sewage Pumping Station (selected for site trial)
Ha Tsuen No. 1 and No. 2 Sewage Pumping Station (selected for site trial)
Design Approaches Planning Planting of groups of trees. Establishment of “Quiet corners”. Selection of planting areas.
Planting Area Selection (1) Coastal habitat (2) Urban area (3) Woodland habitat (4) Rural area Planting space A is preferred over planting space B .
Bat box Design Approaches Hard-landscape Use of nest boxes for birds and bats Water features http://www.bats.org.uk/pages/bat_boxes.html Log pile for insects, amphibians and reptiles Bird box Log pile Eco-pond
Design Approaches Soft-landscape Shrubs and trees are only planted in at-grade level. Native plant species is preferred. Sufficient growing space should be allowed especially for large tree species. Year-round rewards/resources is offered to wildlife.
Recommended Plant Species for the Eco-Landscape Design
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