Chapter Title Page
Figures
Figure 4.1 Ecological Assessment Area
Figure 4.2 Habitat Map and
Species of Conservation Concern (Sheet 1 of 13)
Figure 4.3 Habitat Map and
Species of Conservation Concern (Sheet 2 of 13)
Figure 4.4 Habitat Map and
Species of Conservation Concern (Sheet 3 of 13)
Figure 4.5 Habitat Map and
Species of Conservation Concern (Sheet 4 of 13)
Figure 4.6 Habitat Map and
Species of Conservation Concern (Sheet 5 of 13)
Figure 4.7 Habitat Map and
Species of Conservation Concern (Sheet 6 of 13)
Figure 4.8 Habitat Map and
Species of Conservation Concern (Sheet 7 of 13)
Figure 4.9 Habitat Map and
Species of Conservation Concern (Sheet 8 of 13)
Figure 4.10 Habitat Map and Species
of Conservation Concern (Sheet 9 of 13)
Figure 4.11 Habitat Map and Species
of Conservation Concern (Sheet 10 of 13)
Figure 4.12 Habitat Map and Species
of Conservation Concern (Sheet 11 of 13)
Figure 4.13 Habitat Map and Species
of Conservation Concern (Sheet 12 of 13)
Figure 4.14 Habitat Map and Species
of Conservation Concern (Sheet 13 of 13)
Figure 4.15 Mitigation Measures to
the Impact on Ardeid Night Roost
Appendices
Appendix 4.1 Ecological Survey
Methodology (Terrestrial and Aquatic)
Appendix 4.2 Plates
Appendix 4.3 Report for Benthic Grab Sampling Survey in Aberdeen Channel near Ap Lei Chau Bridge – Wet and Dry
Seasons
Appendix 4.4 Report for Dive Survey at
Appendix 4.5 Plant
List
Appendix 4.6 Habitat
Evaluation
Appendix 4.7 Fauna List
Appendix 4.8 Ardeid Night Roost Survey
This Chapter addresses the potential ecological impacts arising from the construction and operation of the proposed South Island Line (East) and the associated magazine site and barging points. It presented the findings of the literature review and supplementary field surveys conducted from June 2008 to November 2009. The potential impacts to the ecological sensitive receivers within the Assessment Area were assessed and suitable mitigation measures were proposed to minimise the potential adverse impact in accordance with Annexes 8 and 16 of the Technical Memorandum on the Environmental Impact Assessment Process of the Environmental Impact Assessment Ordinance.
The Assessment Area for ecological impact assessment covers an area of 500m radius along the proposed alignment of the South Island Line (East), associated work sites and areas for slope stabilisation work, magazine site and barging points (Figure 4.1).
The methodology and the transect routes for the ecological baseline assessment are presented in Appendix 4.1 and Figures A1-10 in Appendix 4.
4.3 Environmental Legislation, Standards and Guidelines
A number of international conventions, local legislations and guidelines provide the framework for the protection of species and habitats of ecological importance. Those related to this Project are:
Forests and Countryside Ordinance (Cap. 96), which prohibits felling, cutting, burning or destroying of
trees and growing plants in forests and plantations on Government land. The
subsidiary Forestry Regulations (Cap. 96 sub. leg.) prohibit the picking,
felling or possession of listed rare and protected plant species. The list of
protected species in Hong Kong which comes under the Forestry Regulations was
last amended on 11 June 1993 under the Forestry (Amendment) Regulation 1993
made under Section 3 of the Forests and Countryside Ordinance;
Wild Animals Protection Ordinance (Cap. 170), which protects designated wild animals from being
hunted, whilst their nests and eggs are protected from disturbance, destruction
and removal. All birds, most mammals including all cetaceans, certain reptiles,
amphibians and invertebrates are listed under this Ordinance. The Second
Schedule of the Ordinance that lists all the protected animals was last revised
in June 1992;
Country Parks Ordinance (Cap. 208), which is provided for the designation, control and management of country
parks and special area, the establishment of the Country and Marine Parks
Board, and for purposes connected therewith. The Ordinance aims to prohibit or
restrict of the killing, hunting, trapping, molesting or disturbance of any
form of wild life within a country park or special area, the taking of,
destruction of or interference with vegetation within a country park or special
area or the doing of anything therein which will interfere with the soil. It also prohibits or restricts
any lighting of fires within a country park or special area and prevents of
fire hazards. The study area of this Project falls within the
Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586), which was gazetted on 10 March 2006 and effective in
December 2006 to replace the Animals and Plants (Protection of Endangered
Species) Ordinance (Cap. 187) that gives effect to CITES. The Ordinance aims at
regulating the import, introduction from the sea, export, re-export, and
possession or control of certain endangered species of animals and plants and
parts and derivatives of those species and to provide for incidental and
connected matters.
Environmental Impact Assessment Ordinance (EIAO) (Cap. 499), which specifies designated projects under Schedule 2
of the Ordinance, unless exempted, must follow the statutory environmental
impact assessment (EIA) process and require environmental permits for their
construction and operation.
EIAO Guidance Notes No. 6/2002, 7/2002, 10/2004 and 11/2004. These guidance notes provide the observations on Ecological Assessment
from the EIAO perspective, providing the general guidelines for conducting an
ecological baseline survey for ecological assessment, introducing methodologies
for terrestrial, freshwater and marine ecological baseline surveys
respectively.
Annex 8 and 16 of the Technical Memorandum on Environmental Impact
Assessment Process (EIAO-TM):
Annex 8 recommends the criteria that can be used for evaluating ecological
impacts. Annex 16 sets out the general approach and methodology for assessment
of ecological impacts arising from a project or proposal, to allow a complete
and objective identification, prediction and evaluation of the potential
ecological impacts.
Town Planning Ordinance (Cap 131) which gives designation to country parks, conservation area,
green belts, sites of special scientific interest, coastal protection area and
other specified uses to promote conservation, protection and education of the
valuable environment ; and
4.4 Ecological Baseline Information
The main objective of the baseline study is to generate an ecological profile of the proposed development and its vicinity for the following assessment:
i. evaluation of the ecological importance of the wildlife and habitats found;
ii. identification, prediction and evaluation of the potential impacts; and
iii. formulation of appropriate mitigation measures and monitoring programme to avoid, minimize or compensate for any identified adverse ecological impacts
The following sections describe the ecological baseline information based on the literature review and the updated ecological field surveys conducted between June 2008 and November 2009 within the Assessment Area.
4.4.1 Recognized Sites of Conservation Importance
4.4.1.1
4.4.1.2
4.4.2 Habitat Type and Vegetation within the Assessment Area
The proposed alignment runs from Admiralty to South Horizons at Ap
Lei Chau via
▪
▪
Degraded
▪
▪ Shrubland;
▪ Marsh;
▪ Agricultural Land;
▪
▪ Stream;
▪ Drainage Channel;
▪ Open Field;
▪ Wasteland; and
▪ Developed Area.
The distribution of each habitat is shown in the Habitat Maps of Figures 4.2 to 4.14. The areas of each habitat type within the Assessment Area and Project Area are listed in Table 4.1 and Table 4.2 respectively. Project Area refers to the proposed land required for construction works.
Table 4.1: Habitats Present in Assessment Area
|
Habitat |
Assessment Area |
|
|
Area (ha) |
% |
|
|
|
362.53 |
36.7 |
|
Degraded |
4.35 |
0.4 |
|
|
70.60 |
7.2 |
|
Shrubland |
97.07 |
9.8 |
|
Marsh |
0.74 |
0.1 |
|
Agricultural Land |
0.24 |
0.0 |
|
|
23.18 |
2.3 |
|
Stream |
3.52 |
0.4 |
|
Drainage Channel |
2.98 |
0.3 |
|
Open Field |
6.46 |
0.7 |
|
Wasteland |
1.94 |
0.2 |
|
Developed Area |
414.06 |
41.9 |
|
Total |
987.67 |
100 |
Table 4.2: Habitats Present in Project Area
|
Habitat |
Project Area |
|
|
Area (ha) |
% |
|
|
|
5.12 |
13.1 |
|
Degraded |
2.16 |
5.5 |
|
|
5.22 |
13.4 |
|
Shrubland |
2.82 |
7.3 |
|
Marsh |
0.43 |
1.1 |
|
|
1.55 |
4.0 |
|
Drainage Channel |
1.64 |
4.2 |
|
Open Field |
1.75 |
4.5 |
|
Wasteland |
1.03 |
2.7 |
|
Developed Area |
17.21 |
44.2 |
|
Total |
38.93 |
100 |
Representative photographs of each type of habitats are illustrated in Plates 1-12 in Appendix 4.2.
4.4.2.1
Common floral species identified in the woodlands within or in close
proximity to
Other scattered woodland habitats are dominated by common species including Celtis sinensis, Litsea glutinosa, Schefflera heptaphylla, Cratoxylum cochinchinense, Mallotus paniculatus, Ficus variegata, Bridelia tomentosa and Microcos paniculata.
A rare tree species of Gleditsia
australis was recorded in woodland north of
4.4.2.2
Degraded
Degraded woodland refers to woodland habitat greatly degraded by
artificial modification. Inside the Assessment Area, degraded woodlands could
be found at the ex-Canadian
Hospital Site south of
4.4.2.3
4.4.2.4 Shrubland
Shrubland is a subsequent succession stage of grassland. Most of
these habitats are situated on hillsides where human disturbance particularly
hill fire event is not too frequent. Common shrub species include Litsea rotundifolia, Ficus hispida,
Dalbergia benthamii, Lantana camara and Gordonia
axillaris. An orchid species of Geodorum
densiflorum was recorded at the shrubland east of
4.4.2.5 Marsh
A marsh was identified within the Assessment Area at ex-Canadian Hospital Site. This marsh is seasonal in nature and developed from a wasteland formerly planned for building the Canadian Hospital, but was abandoned due to the water logging topography. Like other parts of the former hospital site, the ground is of level profile and has some foundation and drainage structures remain. Common plant species include Leucaena leucocephala, Mikania micrantha, Ranunculus sceleratus and Commelina diffusa.
4.4.2.6 Agricultural Land
Only one small patch of agricultural land was found near village areas at Wong Chuk Hang San Wai. Recorded plant species are common crops such as Raphanus sativus, Ipomoea batatas and Carica papaya.
4.4.2.7
This is a hillside habitat established in areas where shrubs and trees have difficulty re-colonising due to some unfavourable conditions such as frequent hill fires, poor soil quality or strong wind. Common plant species include Pennisetum purpureum, Neyraudia reynaudian and Panicum maximum.
4.4.2.8 Stream
All streams identified within the Assessment Area are rocky streams located along ravine of mountain areas throughout the Assessment Area. Common riparian plants include Alocasia odora, Pteris biaurita and Syngonium auritum.
4.4.2.9 Drainage channel
This habitat refers to those trained water courses for drainage purpose. Apart from some landscape planting or weeds, this habitat is free of vegetation. Inside the Assessment Area of the Project, the major drainage channel is the Wong Chuk Hang Nullah. The downstream section of this channel is under tidal influence. The channel bed is exposed during low tide events and used by waterbirds particularly egrets for foraging.
4.4.2.10 Open Field
Open field refers to bare ground, construction site or exposed areas. With the exception of some common weed species such as Leucaena leucocephala, Mikania micrantha and Bidens alba, these habitats are often without vegetation cover.
4.4.2.11 Wasteland
Wasteland refers to area without determined land use but is densely overgrown with weedy plants, particularly invasive exotics such as Leucaena leucocephala and Mikania micrantha.
4.4.2.12 Developed Area
Developed areas are wholly artificial habitats of a variety of urban land uses such as residential, commercial, industrial and road uses.
4.4.2.13 Project Area (Admiralty to
Most of the proposed works will be underground. Only several works
sites are proposed on surface at the Admiralty urban areas. Two types of habitat will be involved:
plantation and developed area (Figure
4.3).
A total of 121 plant species were recorded within the Project Area of this section. The plant list is presented in Table 1 of Appendix 4.5.
Underground alignment
The new railway line will run in tunnel for a route length of about
3.3km from Admiralty to
4.4.2.14 Project Area (
The alignment of this section is proposed for viaduct running from the Nam Fung portal / ventilation building and box structure to Aberdeen Channel (Figure 4.7). Habitats within the Project Area include woodland, degraded woodland, marsh, plantation, shrubland, hillside grassland, drainage channel, open field, wasteland and developed area.
An area of woodland adjacent to some man-made slopes along
One strip of woodland within the Project Area situates on slopes along the Wong Chuk Hang Nullah. These slopes are relics of isolated hills after the urbanisation of the region. Dominant plants are common native species: Celtis timorensis, Microcos paniculata, Cratoxylum cochinchinense and Sterculia lanceolata. Floral species of conservation interest Aquilaria sinensis was recorded in the woodland along the Wong Chuk Hang nullah.
To mitigate the potential natural terrain hazard to the proposed development, slope stabilization works is anticipated in a hill slope south of Nam Long Shan Road (Figure 4.7). Plant species are those typically found in secondary woodland, such as Mallotus paniculatus, Cratoxylum cochinchinense and Celtis timorensis. The floral species of conservation interest Aquilaria sinensis was also recorded inside.
The degraded woodland within the Project Area is located in the ex-Canadian Hospital site and some nearby
slopes. Like other similar habitat in
The proposed Nam Fung portal ventilation building will be located in the degraded woodland within the ex-Canadian Hospital site (Figure 4.7). The area is vegetated by common pioneer species including Acacia confusa, Macaranga tanarius, Mallotus paniculatus and Ficus hispida. No rare or protected plant species were recorded.
As part of the ex-Canadian Hospital site has a lower ground level with poor drainage, a degraded marsh habitat has been established from the wasteland. The area is flooded with water during the wet season while wholly dried out during the winter time. Wetland species include Ludwigia octovalvis, Brachiaria mutica and Cyperus flabelliformis. The proposed Nam Fung portal will be located inside this degraded habitat.
An area of shrubland and hillside grassland is included in the
Project Area for the potential slope stabilization works north of
Drainage channel refers to the Wong Chuk Hang Nullah which is a concrete structure with vertical banks. Apart from some weed species such as Leucaena leucocephala, the channel is free of vegetation.
Developed area refers to all urbanised land uses including roads,
buildings, concrete slopes and other infrastructures. On the concrete slope
north of
Some areas of open field and wasteland are also include but of low ecological importance.
A total of 359 plant species were recorded within the Project Area of this section. The plant list is presented in Table 2 of Appendix 4.5.
4.4.2.15 Project Area (
This section runs from the proposed Aberdeen Channel railway bridge
to the proposed SOH station at the South Horizons residential estate. Most of
the section will be underground with a few areas requiring surface works (Figure
4.10) for railway bridge,
stations and other associated facilities such as entrances and ventilation
buildings of the underground LET and SOH stations, and a barging areas at
This section covers six types of habitats, including woodland, degraded woodland, plantation, shrubland, hillside grassland, wasteland and developed area.
The woodland within this section, like the one found south of Wong
Chuk Hang Nullah, is the relic of an isolated hill slope north of the
One rare plant species of Gleditsia australis was recorded within this woodland. The species is not currently protected locally but is considered to be of conservation interest for its rarity.
One small area of degraded woodland was located northwest of the
Plantation within the Project Area can be found on amenity areas or slopes along Lee Nam Road and near the residential estates at Sham Wan Towers, Lei Tung Estate, Ap Lei Chau Estate and South Horizons. Common plant species include Albizia lebbeck, Hibiscus rosa-sinensis and Wedelia trilobata.
Associated slope work near the proposed
ventilation building at
The Project Area proposed for the SOH station (Figure
4.11) would cover some areas of
shrubland for potential slope stabilization works and construction of a
ventilation building. Common plant species are Macaranga tanarius, Dalbergia benthamii, Ficus hispida, Litsea
rotundifolia, Lantana camara, Capillipedium parviflorum and Aporusa dioica. No
rare or protected plant species were recorded.
A small piece of wasteland overgrown with Leucaena leucocephala would be included in the Project Area near the
existing Ap Lei Chau Park. Developed area refers to urbanised land uses
including roads, buildings and other infrastructures. The proposed barging
areas at
A total of 262 plant species were recorded within the Project Area of this section. The plant list is presented in Table 3 of Appendix 4.5.
4.4.2.16 Project Area (Magazine Site at Chung Hom Shan)
The proposed Project Area at Chung Hom Shan would make use of part of the existing paved road, engineered slopes, open field and some area of shrubland (Figure 4.13). Common plants colonized the developed area and open field include weed species such as Neyraudia reynaudiana, Leucaena leucocephala and Lantana camara. Abundant Dalbergia hancei, Neyraudia reynaudiana and Sageretia thea were identified in the shrubland. A total of 64 plant species were recorded within the Project Area of this section. The plant list is presented in Table 4 of Appendix 4.5.
4.4.2.17 Project Area (Barging point at
A barging point is proposed at
4.4.2.18 Project Area (Works Site near Wah Kwai Estate)
A works site south of Wah Kwai
Estate is proposed for temporary storage use (Figure 4.14). The proposed area will cover some wasteland
and developed area of low ecological value. Only common urban weed species were
recorded including Acacia confusa, Broussonetia papyrifera, Leucaena leucocephala etc. A total of 14
plant species were recorded within the Project Area of this section. The plant list is presented in Table 6 of Appendix 4.5.
4.4.3 Fauna within the Assessment Area
4.4.3.1 Mammals
Literature Review
A long-term, territory-wide camera trap survey of medium and large
non-flying terrestrial mammals was conducted by AFCD from 2002 to 2006 (Shek
2007). The survey areas covered
A total of 11 mammal species was recorded in
Survey Findings
Only three mammal species including Short-nosed Fruit Bat, Pallas’s
Squirrel and Domestic Cat were sighted in the survey. Scats of Small Indian Civet and Leopard Cat were found in
4.4.3.2 Avifauna
Literature Review
A territory-wide breeding bird survey was conducted by the Hong Kong
Bird Watching Society from 1993-1996 in order to provide ecological baseline data on the
sites potentially under threat of development (Carey et al. 1998). The survey covered all terrestrial habitats in Hong
Kong including
Survey Findings
Due to the high proportion of developed area within the Assessment
Area, the avifauna recorded during the survey is dominated by generalist
species residing in developed areas. The result of the bird surveys are listed
in Table 2b in Appendix 4.7. From
At the woodland in
On the north facing slope of Nam
Long Shan, the shurbland habitat was surveyed and resulted a low abundance of
typical shrubland birds. The presence of Hwamei, Greater Necklaced
Laughingthrush and Black-throated Laughingthrush are typical assemblage in the
shrubland habitat in
At the lower end of WCH Nullah connecting to Aberdeen Channel, a few
wetland bird species, including Little Egret, Great Egret, Chinese Pond Heron,
Grey Heron, Black-crowned Night Heron and Common Kingfisher, were found
foraging at daytime. All the ardeids recorded in the nullah are common in
In the Aberdeen Channel and adjoining typhoon shelter, the assemblage of wetland birds is similar to that of WCH Nullah. Aside from those species recorded in WCH Nullah, Pacific Reef Egret and White-throated Kingfisher were also found foraging at the typhoon shelter area. Despite the heavy marine traffic and polluted sea water, ardeids are commonly seen perching on boats, breakwaters and artificial seawalls to look for prey items.
Black Kites were also regularly seen soaring over the Aberdeen
Channel and adjoining typhoon shelter. The number of foraging Black Kites is
higher in winter when a significant wintering population is present. In the
evening, the Black Kites congregate high over the sky before flying back to
their roosting ground at Magazine Gap in
The avifauna in the potential magazine site at Chung Hom Shan is of different species assemblage to those at
4.4.3.3 Herpetofauna
Literature Review
Despite a dominance of anthropogenic habitat within the Assessment Area, two remarkable reptile species were recorded in previous literature.
White-headed Blind Snake Ramphotyphlops
albiceps, a rare snake species prefers broad-leaf woodland soils, was
recorded in woodland area in
Sighting of a juvenile Green Turtle Chelonia mydas at Aberdeen West Typhoon Shelter was reported to AFCD in December 2006 and was regularly seen since (Wan et. al. 2007). It lingered at the area for 5 months before finally disappeared in February 2007. It was deemed an occasional visitor to the heavily marine trafficked typhoon shelter as the area is not a favourable habitat.
Survey Findings
10
herpetofauna species including one captive original were recorded during the
survey. The survey result is listed in Table
3 in Appendix 4.7. All of the species recorded are common and widespread in the
shrubland, grassland and artificial structure in
4.4.3.4 Butterflies and Dragonflies
Survey Findings
A total of 53 species of Butterfly were recorded during the survey which includes
51 species
found along the proposed alignment and 18 species found in Chung Hom Shan proposed
magazine site. The results of the butterfly survey are listed in Table 4 in Appendix 4.7. Among the butterfly records, 5 are uncommon in
Dragonflies recorded in the Assessment Area are low in abundance and
diversity due to lack of freshwater habitats in the area. The result of the
dragonfly survey is listed in Table 5
in Appendix 4.7. All of the dragonflies recorded are common and widespread in
4.4.3.5 Freshwater Fishes
Literature Review
Territory-wide freshwater fish surveys were conducted by AFCD from
2002 and the result was published in Lee (2004). The survey also covered
Survey Findings
Two stream systems were found in the Assessment Area in WCH.
Freshwater hill streams were found in the woodland and shrubland habitat to the
north of
During the survey, one species of freshwater fish Striped Loach Schistura fasciolata was found in the
hill stream while 3 species, including Mullet Chelon sp., Jarbua Terapon Terapon
jarbua and White-spotted Rabbish Fish Siganus
canaliculatus, were recorded in the WCH Nullah. Striped Loach is common in hill stream throughout
4.4.3.6 Intertidal Community
Literature Review
Intertidal surveys for Drainage
Improvement in Northern Hong Kong Island - Hong Kong West Drainage Tunnel
Environmental Impact Assessment (Black & Veatch 2006) were conducted on the rocky shore at
Survey Findings
The proposed project involves a small scale dredging works at
Aberdeen Channel. The suspended sediment arising from the dredging works may
adversely affect the intertidal community. Intertidal community surveys using
both the transect and walk through method were conducted at the potentially
affected area which covers the habitats of artificial seawall, vertical
artificial seawall and boulder shore. The survey locations are depicted in Figure
B1 in Appendix 4 and the survey results are
summarized in Tables 7a-g in Appendix 4.7. The intertidal community recorded in the area are common and
typical to
At
4.4.3.7 Coral Community
Literature Review
Survey Areas near Wong Chuk Hang
Only a few ecological surveys
were conducted along the coast of
Assessment of substrate and ecological attributes were performed by semi-quantitative Rapid Ecological Assessment (REA) surveys. In the survey, a total seven hard (Psammocora superficialis, Montipora cf. turgescens, Plesiastrea versipora, Cyphastrea serailia, Leptastrea pruinosa, Goniopora stutchburyi and Porites sp.) and two soft coral (Lobophytum depressum and Euplexaura sp.) species were found on boulders at shallow water.
Survey Areas near Telegraph Bay
The latest
information on coral community around the construction area at
Transect and bounce dive surveys
were conducted along the coastline of
Survey Findings
The
construction of the pier foundation of the railway bridge crossing Aberdeen
Channel at WCH and marine piling for the construction of a tipping hall at
Ecological dive survey was conducted at Aberdeen South Typhoon
Shelter and
Wong Chuk Hang Site
Survey at the artificial seawall at WCH under the Ap Lei Chau Bridge found that the sea bottom was mainly
dominated by cobbles and sand at shallow area and mud and silt towards the
centre of the channel. The bottom substrate was, however, mainly covered by
anthropogenic wastes. The vertical seawall was generally covered by tunicates,
barnacles, mussels, tube worms and bryozoans while the cobbles and sand bottom
are covered by waste materials such as tyres and wood pieces. Scattered
colonies of hard corals Oulastrea
crispata were observed on these wastes especially on the tyres. Oulastrea crispata is a common coral
species in
REA surveys were performed at 2 locations at WCH on the shallow hard substrate where hard and soft corals were observed in the spot dive survey. The common epibenthos on the hard surface included bryozoans, tunicates, sponges and barnacles. Colonies of hard coral, Oulastrea crispata, were found on both boulder and tyre surface. A species of octocoral, Echinomuricaea sp., was recorded with 2 colonies growing on the vertical seawall.
REA dive survey was conducted at 3 locations in
4.4.3.8 Marine Benthic Community
Literature Review
A detailed survey on
Survey Findings
A grab sampling survey was performed in Aberdeen Channel near the Ap Lei Chau Bridge in January and April 2009 to collect data and assess the conditions of the benthic communities. Details of the surveys are reported in Appendix 4.3. The benthic organisms in the collected samples were of very low abundance and diversity. Only 7 individuals from 5 species were found in the 9 samples (3 replicate samples from each of the three sampling locations) during the dry season survey, and only 13 individual from 7 species were recorded during the wet season survey. No species of conservation importance was recorded in the survey. Species richness and diversity in the assessment area are generally low (species richness <5 and diversity <2).
4.5 Ecological Value of Sites and Species
Habitats identified within the Assessment Area were evaluated according to the guidelines set out in Annex 8 of the EIAO-TM. Overall ecological values for each habitat type were ranked. Rankings starting with the highest ecological value range from:
▪ High
▪ Moderate-high
▪ Moderate
▪ Moderate-low
▪ Low
▪ Very Low
4.5.1 Evaluation of the Project Area
The proposed Project Area is evaluated in accordance with the criteria set forth in Annex 8, Table (2) of the EIAO-TM:
Table 4.3: Ecological Evaluation of Project
Area (Admiralty to
|
Criteria |
(plantation and developed area) |
|
Naturalness |
Both developed area and plantation are man made habitats. |
|
Size |
0.68ha of developed area and 1.92ha of plantation. |
|
Diversity |
Flora: Low Fauna: Low |
|
Rarity |
Common habitat and species (flora and fauna) |
|
Re-creatability |
Developed area is man made habitat that can be re-created easily. |
|
Fragmentation |
No fragmentation |
|
Ecological linkage |
No significant ecological linkage |
|
Potential value |
Low |
|
Nursery/ breeding ground |
No nursery / breeding grounds are observed. |
|
Age |
No available information |
|
Abundance/ Richness of wildlife |
Low in wildlife abundance |
|
Ecological value |
Low |
Table 4.3a Ecological Evaluation of Project Area (Nam Fung Tunnel alignment beneath the
|
Criteria |
(underground alignment) |
|
Naturalness |
Dominant habitat is woodland which is largely natural; other natural habitats include shrubland and stream; hillside grassland is semi-natural; while plantation, drainage channel and developed area are man made. |
|
Size |
The
underground alignment is about 3.3km in length, but no project area is
proposed on ground level within the |
|
Diversity |
High
floristic diversity and moderate fauna diversity for those around |
|
Rarity |
Besides
a few uncommon woodland bird species, most of the fauna species recorded are
common in |
|
Re-creatability |
|
|
Fragmentation |
No fragmentation |
|
Ecological linkage |
Habitats
within |
|
Potential value |
High ecological potential. |
|
Nursery/ breeding ground |
Nursery and breeding ground for various fauna species but no significant breeding population for conservation concerned species was identified. |
|
Age |
Over
30 years, the |
|
Abundance/ Richness of wildlife |
Moderate abundance of wildlife |
|
Ecological value |
High |
Table 4.4: Ecological Evaluation of Project
Area (
|
Criteria |
(woodland, degraded woodland, marsh, plantation, drainage channel, shrubland, hillside grassland, wasteland, open field and developed area) |
|
Naturalness |
The woodland habitat are largely natural secondary woodland; Degraded woodland, shrubland, hillside grassland and marsh are
modified habitats which are semi-natural; |
|
Size |
4.84ha of
woodland, 2.01ha of degraded woodland, 0.43ha of marsh, 2.12ha of plantation,
1.64ha of drainage channel, 0.11ha of shrubland, 0.29ha of hillside
grassland, 0.09ha of wasteland, 0.99ha of open field and 11.86ha of developed
area |
|
Diversity |
Flora: moderate for the woodland habitat; while low for other habitats Fauna: Low |
|
Rarity |
Common habitat and faunal species. The
recorded Ailanthus fordii in The
recorded Aquilaria sinensis is
listed under the Protection of Endangered Species of Animals and Plants
Ordinance (Cap. 586) and as Near Threatened in Mainland Gleditsia australis is a rare native
tree species but has no protection status in A rare herb Houttuynia cordata was recorded on a retaining wall along the edge of the degraded woodland. A
Potential Global Concern species, Short-legged Toad Megophrys brachykolos
was recorded at the woodland near |
|
Re-creatability |
Degraded woodland, plantation, low-quality marsh are re-creatable; Drainage channel, wasteland and developed area are man made habitats that can be re-created easily. |
|
Fragmentation |
Woodland, plantation are fragmented within the area dominated by urbanized land uses |
|
Ecological linkage |
The
drainage channel (Wong Chuk Hang Nullah) has minor ecological linkage with
the adjoining woodland in providing a roosting and foraging habitat for
ardeids. The wetland bird assemblage foraging at
WCH Nullah and Aberdeen Channel are interchangeable. |
|
Potential value |
Moderate for woodland; but low for other habitats |
|
Nursery/ breeding ground |
Roosting
grounds for ardeids are observed in the
degraded woodland in WCH Nullah whilst roosting ardeids are
also commonly seen along the Aberdeen Channel. |
|
Age |
No available information |
|
Abundance/ Richness of wildlife |
Generally low abundance in wildlife but moderate
abundance of ardeids along the Wong Chuk Hang Nullah. |
|
Ecological value |
Moderate-low
in overall, but moderate for woodland areas at |
Table 4.5: Ecological Evaluation of Project
Area (
|
Criteria |
(woodland, degraded woodland, plantation, shrubland, hillside grassland, wasteland and developed area) |
|
Naturalness |
The woodland and shrubland habitats are natural;
Degraded woodland and hillside grassland is semi-natural; |
|
Size |
0.28ha of woodland, 0.15ha of degraded woodland, 1.16ha of plantation, 1.43ha of shrubland, 1.26ha of hillside grassland, 0.07ha of wasteland and 3.66ha of developed area |
|
Diversity |
Flora: Low for all sorts of habitats Fauna: Low |
|
Rarity |
Common
habitat and species (flora and fauna), except a rare tree species of Gleditsia australis was recorded
inside the woodland north of the |
|
Re-creatability |
Degraded woodland, shrubland, plantation and hillside grassland are re-creatable; Wasteland and developed area are man made habitats that can be re-created easily. |
|
Fragmentation |
Woodland,
plantation are fragmented within the area dominated by urbanized land uses |
|
Ecological linkage |
No significant ecological linkage |
|
Potential value |
Low |
|
Nursery/ breeding ground |
No nursery / breeding grounds are observed |
|
Age |
No available information |
|
Abundance/ Richness of wildlife |
Low in wildlife abundance |
|
Ecological value |
Low |
Table 4.6: Ecological Evaluation of Project Area (Magazine Site at Chung Hom Shan)
|
Criteria |
(shrubland, open field and developed area) |
|
Naturalness |
mainly man made habitats; the shrubland is a
natural secondary habitat. |
|
Size |
1.28ha of shrubland, 0.76ha of open field and 0.22ha of developed area |
|
Diversity |
Flora: Low Fauna: Low |
|
Rarity |
Common habitat and species (flora and fauna), except a rare butterfly species Red Lacewing Cethosia biblis biblis recorded in the shurbland and a rare Eurasian Eagle Owl recorded on the cliff near the proposed magazine site. |
|
Re-creatability |
Can be re-created easily. |
|
Fragmentation |
No fragmentation |
|
Ecological linkage |
No ecological linkage |
|
Potential value |
Low |
|
Nursery/ breeding ground |
No nursery / breeding grounds are observed |
|
Age |
No available information |
|
Abundance/ Richness of wildlife |
Low in wildlife abundance |
|
Ecological value |
Low |
Table 4.7: Ecological Evaluation of Project
Area (Barging point at
|
Criteria |
(developed area and plantation) |
|
Naturalness |
All are man made habitats. |
|
Size |
0.02ha of plantation and 0.25ha of
developed area |
|
Diversity |
Flora: Low Fauna: Low |
|
Rarity |
No rare species (flora and fauna) were found. |
|
Re-creatability |
Can be re-created easily. |
|
Fragmentation |
No fragmentation |
|
Ecological linkage |
No ecological linkage |
|
Potential value |
Low, as the area is only for urban land use |
|
Nursery/ breeding ground |
No nursery / breeding grounds are observed |
|
Age |
No available information |
|
Abundance/ Richness of wildlife |
Low in wildlife abundance |
|
Ecological value |
Very Low |
Table 4.8: Ecological Evaluation of Project Area (Works Site near Wah Kwai Estate)
|
Criteria |
(wasteland and developed area) |
|
Naturalness |
Wholly man made habitats. |
|
Size |
0.87ha of wasteland; and 0.54ha of
developed area |
|
Diversity |
Flora: Low Fauna: Low |
|
Rarity |
No rare species (flora and fauna) were found. |
|
Re-creatability |
Can be re-created easily. |
|
Fragmentation |
No fragmentation |
|
Ecological linkage |
No ecological linkage |
|
Potential value |
Low, as the area is only for urban land use |
|
Nursery/ breeding ground |
No nursery / breeding grounds are observed |
|
Age |
No available information |
|
Abundance/ Richness of wildlife |
Low in wildlife abundance |
|
Ecological value |
Very Low |
4.5.2 Evaluation of Habitats (Offsite) within the Assessment Area
Evaluation of offsite (i.e. areas outside the proposed Project Area) habitats within the Assessment Area is presented in Tables 1-12 in Appendix 4.6.
4.5.3 Evaluation of Floral Species of Conservation Interest within Project Area
All the species of conservation concern were evaluated in accordance with the criteria set forth in Annex 8, Table (3) of the EIAO-TM. Table 4.9 evaluate the floral species found within the proposed worksite areas (on-site).
Table 4.9: Ecological Evaluation of Floral Species within Proposed Worksite Area (On-site)
|
Species |
Location |
Protection Status |
Distribution |
Rarity |
|
Ailanthus fordii |
- Planting area near |
Listed under the Forestry Regulations (Cap. 96 sub. leg.); Status
of Near Threatened (NT) in |
Por
Kai Shan, Ma On Shan, Cheung Sha, Tai |
Rare (1) for wild species; but common in amenity planting |
|
Aquilaria sinensis |
- Inside the woodland north of -
On the concrete slope north of - Inside the woodland south of Nam Long Shan Road; - Inside the plantation south of Nam Long Shan Road; - Inside the woodland area south of the Wong Chuk Hang nullah; |
Listed under the Protection of Endangered Species of Animals and Plants Ordinance (Cap 586); Status
of Near Threatened (NT) in |
Distributed
widely in |
Common (1) |
|
Gleditsia australis |
-
Inside the woodland north of -
On the concrete slope north of -
Inside the woodland north of |
Not
protected in Hong Kong and |
|
Rare (1) |
|
Lagerstroemia fordii |
Inside the woodland north of |
Listed under the Forestry Regulations (Cap. 96 sub. leg.); Status
of vulnerable (VU) in |
Wong Chuk Hang, Tai Tam, Aberdeen, Hok Tsui, Mt. Nicholson, Pok Fu Lam, Happy Valley and Lantau. (2) |
Restricted (1) |
|
Pavetta hongkongensis |
Inside
the woodland north of |
Listed under the Forestry Regulations (Cap. 96 sub. leg.); |
Distributed
widely in |
Common (1) |
|
Houttuynia cordata |
On a retaining wall along the edge of the degraded woodland south of the Wong Chuk Hang nullah |
Not
protected in Hong Kong and |
Sha Lo Tung (1); Lam Tsuen, Sha Lo Tung (2) |
Very rare (1) |
Reference source:
(1)
(2) Hong Kong Plant Check List 2001;
(3)
Rare and Precious Plants of
4.5.4 Evaluation of Faunal Species of Conservation Interest within Project Area
Fauna species of conservation concern found within the proposed worksite areas (on-site) were evaluated in Table 4.10 in accordance with the criteria set forth in Annex 8, Table (3) of the EIAO-TM.
Table 4.10: Ecological Evaluation of Faunal Species within Proposed Worksite Area (On-site)
|
Common Name |
Scientific Name |
Location |
Protection Status |
Distribution |
Rarity |
Level
of Concern |
|
Mammals |
||||||
|
East
Asian Porcupine |
Hystrix brachyura |
|
Cap. 170 |
Wide
distribution in |
Abundant |
PGC |
|
Masked
Palm Civet |
Paguma larvata |
|
Cap. 170 |
Wide
distribution in |
*Common |
PRC |
|
Red Muntjac |
Muntiacus muntjak |
|
- |
Wide
distribution in |
Abundant |
PRC |
|
Leopard Cat |
Prionailurus bengalensis |
Scats
recorded at Chung Hom Shan and |
Cap. 170 and 586, CITES, CRDB (V) |
Wide
distribution in |
Uncommon |
- |
|
Leschenault's Rousette |
Rousettus leschenaulti |
Ap Lei Chau |
Cap. 170 |
Fairly
wide distribution in |
Common |
LC |
|
Short-nosed
Fruit Bat |
Cynopterus sphinx |
Ap Lei Chau |
Cap. 170, CRDB (I) |
Wide
distribution in |
Abundant |
LC |
|
Birds |
||||||
|
Grey
Heron |
Ardea cinerea |
Wong Chuk Hang |
Cap. 170 |
Common in wetland habitat |
Common |
PRC |
|
Great
Egret |
Egretta alba |
Wong Chuk Hang |
Cap. 170 |
Common in wetland habitat |
Common |
PRC(RC) |
|
Intermediate
Egret |
Egretta intermedia |
Wong Chuk Hang |
Cap. 170 |
Common in freshwater wetland habitat |
Common |
RC |
|
Little
Egret |
Egretta garzetta |
Wong Chuk Hang, Ap Lei Chau |
Cap. 170 |
Common in all type of wetland habitat |
Common |
PRC(RC) |
|
Pacific
Reef Egret |
Egretta sacra |
Chung Hom Shan |
Cap. 170, CRDB(R) |
Widespread in coastal area |
Common |
(LC) |
|
Cattle
Egret |
Bubulcus ibis |
|
Cap. 170 |
Common in freshwater wetland or open
grassland |
Common |
(LC) |
|
Chinese
Pond Heron |
Ardeola bacchus |
|
Cap. 170 |
Common in wetland habitat |
Common |
PRC(RC) |
|
Black-crowned Night Heron |
Nycticorax nycticorax |
|
Cap. 170 |
Common in wetland habitat |
Common |
(LC) |
|
Black Kite |
Milvus migrans |
|
Cap.
170 and 586 |
Common and widespread in |
Common |
(RC) |
|
Crested
Serpent Eagle |
Spilornis cheela |
|
Cap. 170 and 586, CRDB(V) |
Mainly in mature woodland habitat |
Uncommon |
(LC) |
|
White-bellied Sea Eagle |
Haliaeetus leucogaster |
|
Cap.
170 and 586 |
Widespread in coastal area. |
Uncommon |
(RC) |
|
Crested Goshawk |
Accipiter trivirgatus |
|
Cap. 170 and 586, CRDB (R) |
Mainly in woodland habitat |
Common |
- |
|
Swinhoe's
Snipe |
Gallinago megala |
Chung Hom Shan |
Cap. 170 |
Mainly in freshwater marsh. |
Uncommon |
LC |
|
Greater Coucal |
Centropus sinensis |
Ap Lei Chau, Chung Hom Shan |
Cap. 170, CRDB (V) |
Widespread in shrubland habitat |
Common |
- |
|
Lesser Coucal |
Centropus bengalensis |
Wong Chuk Hang |
Cap. 170, CRDB (V) |
Widespread in shrubland habitat |
Common |
- |
|
Eurasian
Eagle Owl |
Bubo bubo |
Chung Hom Shan |
Cap. 170 and 586, CRDB (R) |
Mainly in open shrubland |
Rare |
RC |
|
Pacific Swift |
Apus pacificus |
|
Cap. 170 |
Widespead in |
Uncommon |
(LC) |
|
White-throated Kingfisher |
Halcyon smyrnensis |
|
Cap. 170 |
Widespread in |
Common |
(LC) |
|
White-shouldered Starling |
Sturnus sinensis |
Chung Hom Shan |
Cap. 170 |
Widespread in open field or wetland
habitat. |
Uncommon |
(LC) |
|
Herpetofauna |
||||||
|
Common Rat Snake |
Ptyas
mucosus |
|
Cap 586, CRDB(E) |
Widely
distributed throughout |
Common |
- |
|
Butterflies |
||||||
|
Baron |
Euthalia aconthea aditha |
|
- |
Widely
distributed in woodland throughout |
Uncommon |
LC |
|
Red Lacewing |
Cethosia biblis |
Chung Hom Shan |
- |
Widely distributed throughout |
Rare |
- |
|
Dragonflies |
||||||
|
Emerald
Cascader |
Zygonyx iris insignis |
|
- |
Widely
distributed in clean and rapidly flowing forested streams throughout |
Abundant |
PGC |
|
Freshwater Fishes |
||||||
|
Common
Carp |
Cyprinus carpio |
|
IUCN(V) |
Not common in streams but occurs in many reservoirs and cultivated in fishponds |
Not common in streams |
- |
|
Predaceous
Chub |
Parazacco spilurus |
|
CRBD(V) |
A widespread species occurring in most unpolluted hill streams in both upper and lower courses |
Common |
- |
|
|
Oreochromis mossambicus |
|
IUCN(NT) |
Widespread in brackish waters, freshwater ponds, ditches, rivers and reservoirs. The fish is also cultivated in some local fish farms |
Common |
- |
Note: “Rarity” refers to local abundance in
Reference
source:
Protection
Status: AFCD Biodiversity Database, 2009.
IUCN – IUCN Red List:
CRDB –
Level of Concern: LC = Local Concern, RC
= Regional Concern, PRC = Potential Regional Concern, PGC = Potential Global
Concern. Letters in parentheses indicate that the assessment is on the basis of
restrictedness in breeding and/or roosting sites rather than in general
occurrence. (Fellowes et al. 2002)
Mammals - Distribution and Rarity: AFCD Biodiversity Database, 2009 and Shek, 2006. (* follows Shek, 2007).
Herpetofauna – Distribution: AFCD Biodiversity Database, 2009. Rarity: Karsen et al. 1998.
Butterfies - Distribution: AFCD Biodiversity Database, 2009. Rarity: Yiu and Young, 2002.
Dragonflies – Distribution: AFCD Biodiversity Database, 2009. Rarity: Wilson et al. 2004.
Freshwater
Fish – Distribution: AFCD Biodiversity Database, 2009.
Rarity: Lee et al., 2004.
4.6 Identification, Prediction and Evaluation of Environmental Impact
The surface works of the proposed project comprises site clearance, cut and cover, viaduct /railway station construction and associated infrastructure works. The potential ecological impacts for the proposed development during construction and operational phase include direct habitat loss, direct impact on floral species of conservation interest and secondary impacts on faunal species of ecological significance including disturbance impacts and loss of foraging, breeding and roosting sites. Details of the potential impacts are identified and assessed as below and the summary of the impact assessment is presented in Table 4.12.
4.6.1 Terrestrial Habitat Loss
Terrestrial habitat loss would be resulted from site clearance for works operation / temporary storage, construction of viaduct / station and associated facilities. Loss of different types of habitats within the Project area is presented in the following table.
Table 4.11: Habitat Loss
|
Habitat |
Permanent Loss |
Temporary Loss |
|
|
0.43ha |
4.69ha |
|
|
0.63ha |
4.59ha |
|
Marsh |
0.22ha |
0.21ha |
|
Degraded |
0.45ha |
1.71ha |
|
Shrubland |
0.12ha |
2.70ha |
|
|
0 ha |
1.55ha |
|
Wasteland |
0 ha |
1.03ha |
|
Drainage Channel |
0.78ha |
0.86ha |
|
Open Field |
0.34ha |
1.41ha |
|
Developed Area |
7.32ha |
9.89ha |
|
Total |
10.29ha |
28.64ha |
In the above table, all habitats within the boundary of Project Area are assumed to be affected during the construction, and therefore the size of the areas potentially to be affected is considered as the worst case scenario.
The permanent loss of habitats would be resulted from the construction of the proposed permanent structures which include railway stations, viaduct and ventilation shafts. Other habitats within the Project Area are considered to be temporary loss during the construction period as these habitats could be reinstated after the completion of the project. The table above also represents the worst-case scenario of the slope works extent, the actual vegetation loss is dependent on the natural terrain hazard study during the detailed design stage.
As shown in Table 4.11, major habitats include developed area, plantation and woodland with some degraded woodland, shrubland, hillside grassland, marsh, drainage channel, wasteland and open field in small size. Streams and agricultural land identified within the Assessment Area will not be affected by the project as no works are proposed on these two types of habitat.
Impact of habitat loss due to the construction works in different sections is described in the sub-sections below:
4.6.1.1
Project Area (Admiralty to
Works proposed in this section include the construction of the ADM
station, ventilation building at
Habitats to be affected include developed area and plantation only. As evaluated in Table 4.3, the ecological value of this Project Area section is low. Loss of wholly man made habitats will not cause significant ecological impact.
The Aberdeen Country Park and Nam Fung Road Woodland SSSI would be undisturbed by the proposed project as tunneling is proposed within the Country Park while the fung shui wood will be avoided by the proposed alignment as a separation distance of about 200m between the fung shui wood and the works sites can be provided. No habitat loss of these ecologically sensitive areas will be resulted.
4.6.1.2
Project Area (
Works proposed in this section include the construction of Nam Fung ventilation building / portal, box structure at ex-Canadian Hospital site, OCP station, WCH station, the viaduct alignment (from the Nam Fung portal to Aberdeen Channel) and potential slope stabilization works on a few areas.
At the eastern end of this section, slope stabilization works is
anticipated in a hillside area north of
To the south, the Project Area at the ex-Canadian Hospital site (Figure 4.7) is included for the construction of Nam Fung ventilation building / portal and box structure between the ventilation building and the viaduct. The proposed works for this part would cause impact on a marsh, degraded woodland and wasteland. Permanent loss of degraded woodland and the low-quality marsh is anticipated. Other degraded woodland and wasteland habitats within this section will only be affected temporarily during the construction stage.
For the section of Project Area between the box structure and the WCH station (Figure 4.7), major affected habitats along the alignment will be plantation, drainage channel and developed area. All are artificial habitats of low ecological importance. However, a woodland area south of Nam Long Road will also be included for the potential slope stabilization works. As no permanent structures are proposed on the slope, the habitat loss of the woodland will only be temporary in nature and will be reinstated after the completion of works.
To the west, the viaduct alignment generally runs alongside the Wong Chuk Hang Nullah. The Project Area of this section will cover woodland, degraded woodland, drainage channel, open field and developed area (Figures 4.7to 4.9). The woodland area would be cleared during the construction for slope stabilization and the viaduct structures. The area underneath the proposed viaduct would be permanently lost while other areas will only affected temporarily and reinstated after the completion of works.
Although various types of habitat will be affected within this
section of Project Area (
The two affected woodlands found at
The habitat quality of the woodland along Wong Chuk Hang Nullah is
not high for its isolated location, fragmented profile and large interface with
urbanized environments. Loss of the habitat would affect the roosting and
feeding grounds of some common generalist birds such as bulbuls and Japanese White-eye commonly seen in urban fringe and the night
roost site for ardeids. Impact assessment for the ardeids roosting and foraging
at the WCH nullah is detailed in Section
4.6.5.
The unmitigated impact of woodland loss is considered to be moderate and mitigation measure to alleviate the impact is required. Recommended mitigation measures include habitat reinstatement for temporary woodland loss and habitat compensation for permanent woodland loss. Details of ecological mitigation measures are described in Section 4.7.
The unmitigated impact of degraded woodland loss is considered to be moderate-minor for their low habitat quality and fragmented profile. Impacts on other habitats are considered to be insignificant due to their low ecological value.
4.6.1.3
Project Area (
Works proposed in this section include the construction of entrances
and ventilation buildings of the underground LET and SOH stations, and barging
areas at
At the eastern end of this section, the viaduct from Wong Chuk Hang
area will end at the southern side of
The permanent structure of the
tunnel ventilation fan chamber will cause permanent loss of some areas of
degraded woodland and plantation. However, the permanent loss will only be very
small in size as the footprint of the structure has been minimised as far as
possible. As the cut and cover method is proposed, the other affected area will
only be disturbed temporarily and able to be reinstated after the completion of
the works.
Along the underground tunnel from Ap Lei Chau Drive to the underground SOH station (Figure 4.10), habitat loss due to the entrances and ventilation shafts of LET and SOH stations will not cause significant ecological impact as these structures and its works areas only cover artificial habitats plantation and developed area, of low ecological value.
The ventilation building near
The SOH ventilation building at
The two works areas at
As evaluated in Table 4.5, the overall ecological value of the Project Area of this section
is low. The key ecologically sensitive receiver would be the woodland habitat
north of the
4.6.1.4
Project Area (Magazine Site at Chung Hom Shan)
Works proposed in this section include the construction of a magazine site and slope stabilization works in the surrounding hill slopes.
As no permanent structures are proposed, the habitat loss of the existing shrubland, open field and developed area will only be temporary. Taking into account the low ecological value of the Project Area (refer Table 4.6) and the temporary nature of the impact, no significant ecological impact is anticipated.
4.6.1.5
Project Area (Barging point at
Works proposed in this section include only the construction of a barging point.
As the Project Area will only affect mainly developed area with very small area of plantation, no adverse ecological impact is anticipated.
4.6.1.6
Project Area (Works Site near Wah Kwai Estate)
No construction works is proposed at this Project Area. The area will only be used as temporary storage site.
As the Project Area will only affect wasteland and developed area of
low ecological value, no adverse ecological impact is anticipated.
4.6.2
Disturbance to
The
Direct encroachment on the natural
habitat within the
4.6.3 Impact on Floral Species of Conservation Interest
Five floral species of conservation interest were identified within the Project Area: Aquilaria sinensis, Gleditsia australis, Lagerstroemia fordii, Pavetta hongkongensis and Houttuynia cordata (refer Table 4.9 in Section 4.5).
Although Ailanthus fordii is listed under the Forestry Regulations (Cap. 96 sub. leg.) for its rarity status in the wild, the recorded individuals within the Project Area are cultivated for urban landscape. Therefore it is not considered as species of conservation interest and no adverse ecological impact is anticipated for its removal. No specific ecological mitigation is required for these cultivated individuals.
Despite the protection status of Aquilaria
sinensis under the Cap. 586 and the Category II status in
Gleditsia australis is not protected by local or regional legislation but it is listed
as a rare native species in Corlett’s study “
The recorded Houttuynia
cordata was found on the top of a retaining wall of small growing area
(only few m2). Like G.
australis, it is a rare plant in
As all the plants are located within the Project Area where various construction activities are proposed and ground re-profiling is required, removal of these plants is considered to be unavoidable. Taking into account the commonness of Aquilaria sinensis and Pavetta hongkongensis, and low abundance of Gleditsia australis, Lagerstroemia fordii and Houttuynia cordata, the impact will not cause adverse effect on the species. However, mitigation measures to further minimize the impact are recommended.
4.6.4
Impact
on the Short-nosed Fruit Bats at
A Chinese Fan-palm beside
4.6.5 Impact on the Ardeids Roosting and Foraging at WCH Nullah
4.6.5.1
Impact on Ardeid Night Roost
Loss of roosting habitat
The degraded woodland area beside WCH Nullah was used by ardeid as a
night roosting site (Location refers to Figure
4.15). The slope enhancement
work for the construction of viaduct would clear a degraded woodland area which
is part of the wooded area used by the ardeid. The site clearance and tree
felling would cause a loss of night roosting habitat for the ardeid. Avoiding
the impact to the ardeid night roost by considering alternative alignment
options is identified to be impracticable as evaluated in Section 2.7.4. The viaduct option is selected as the preferred option for the railway
section between Nam Fung portal and Aberdeen Channel Crossing taking into
account the technical and other constraints, and environmental factors have
been duly considered in selecting the horizontal alignment of the viaduct
section.
As reported in Appendix 4.8, the degraded woodland is mainly used by Little Egrets as a night roost. The roosting population is highly variable from around 40 in August 2008 to more than 400 in December 2008 (Table 1 and Figure 1 in Appendix 4.8). The high abundance of Little Egrets in winter compared with lowest summer population indicated the presence of wintering population. Therefore, the potential impact would be larger if the construction activities such as site clearance and tree felling works are conducted in winter.
The ardeids would respond to the impact by shifting their roosting
locations to neighboring trees or, to a greater extent, to other suitable
habitat along the Aberdeen Channel. Although no existing alternative night roost was found in
the neighboring area during the ardeid night survey (refer Section 3 in Appendix 4.8 for the survey), it is
thought that the ardeid can readily settle on similar habitat in adjacent area
for night roosting. In view of the availability of suitable habitat at the
adjacent area, it is predicted that the ardeids would either choose the
degraded woodland next to the existing roost or other wooded area along the
Aberdeen Channel for the alternative night roost. As observed at the site, the
uphill woodland habitats to the west of existing night roost and the south
facing slope to the south of the Holy Spirit Seminary have higher potential for
ardeid resettlement in view of the similarity in vegetation type and geological
setting to the existing roost. During operation phase, the works area along the
viaduct would be replanted to provide vegetation cover which could recover the
potential for ardeid roosting. Ardeid roost closely located with amenity
facilities or railway has been demonstrated in other existing cases in
Evaluation of the potential impact on the roosting ardeids is based on the assessment of demographic parameters such as survival and reproductive success because from a conservation perspective, human disturbance of wildlife is important only if it affects survival or fecundity and hence causes a population to decline (Sutherland 1998; Gill 1999). The potential impact on the fecundity of the roosting ardeid is negligible as the site is only used primarily for wintering night roosting but not for breeding purpose. On the other hand, the possibility for the exclusive ardeid night roost in WCH Nullah to transform into an egretry for breeding purpose is low since there was no such case happened in the last decade in Hong Kong although egretries in Hong Kong sometimes are used for night roosting in non-breeding season. In contrast to the ecologically importance of egretry in account of its function of reproduction, the ecological value of an exclusive ardeid night roost in the artificially modified habitat in WCH Nullah is comparatively low in this aspect.
The potential impact on the
fitness and vital rate is minor because there would be no substantial influence
on their foraging habitat and behavior. Indeed, majority of the ardeids
roosting at the WCH Nullah were foraging far distance from the
As was reported in Section 4
in Appendix 4.8, ardeid night roost is rather unstable and the change of night
roosting location could happen naturally. The change of behavior does not necessarily associate with an impact on the survival rate of
an individual. In this case, if
without mitigation, the potential ecological impact is evaluated as moderate
because of a high night roosting population of conservation concerned species would be affected in winter but the impact is only limited to behavioral level.
Disturbance to the roosting ardeid
The construction of the viaduct at Wong Chuk Hang would affect the ardeid night roosting at the woodland at the south of WCH Nullah through habitat loss and off-site disturbance. Since a portion of the night roost area would be cleared concurrently with other site formation and mobilization works, the location of the night roost would not be the same to that at pre-construction. As predicted in the assessment on potential habitat loss, the ardeid night roost would relocate either to the neighbouring woodland or to other suitable area along the Aberdeen Channel. In the latter case, the off-site disturbance to the night roosting ardeid during operation phase is negligible because the ardeid would unlikely settle on the project area for night roosting during construction phase. Therefore, the following impact assessment is based on the prediction of the former case, the ardeid night roost only slightly shifted to neighboring woodland.
The ardeid habitually return to the night roost at every evening at around an hour before sunset. The construction activities, presence of human and vehicles nearby and night-time glare would interfere with the night roosting ardeid. Disturbance impacts would be greater during the winter period, when a larger number of ardeids present in the night roost. The roosting ardeid would adapt to the change through changing to an optimal roosting location nearby or, at larger extent, move to other site along Aberdeen Channel.
In case the night roost is abandoned, the ardeids would find another suitable habitat at neighboring area for night roosting. A change of night roosting site would cause a temporary change in behavior but would not affect the fitness and vital rate as their breeding and roosting site are not affected. The influence on behavioral level would cause the roosting ardeid spending more energy to adopt the new night roost temporarily. In considering that the disturbance will not bring a significant impact on the survival and reproductive success, the change of behavior would not lead to a decline in population and therefore not to be considered as significant from a conservation perspective. As reported in Section 3 in Appendix 4.8, change of ardeid night roost could happen naturally with no evidence of adverse impact on their survival rate. As such, the potential off-site disturbance impact to the night ardeid night roost which leads to a change of behavior is evaluated as moderate significance, if without mitigation measures.
On the other hand, as observed in other ardeid night roosts in Hong Kong, almost all the locations are situated near water no matter sea, pond or river (refer Section 4 in Appendix 4.8). Water source is therefore regarded as an important element for ardeid night roost. This observation matched with the night roost in Wong Chuk Hang in which the location is in close proximity to the nullah. The proposed project would not deck over the lower section of the nullah permanently and therefore maintain a water source, an element for the existence of ardeid night roost, in both construction and operation phase. Although disturbance impact would arise from the construction activities, one of the key environmental factors for ardeid night roost would remain unchanged throughout the construction phase.
During operation phase, the ardeid roost would change to another location either at the
degraded woodland beside the nullah or at somewhere outside the WCH Nullah area. If the new night roost is located
beside the WCH Nullah, the operation of the train would cause disturbance to the night
roosting ardeids. The moving train and the associated noise would interfere
with the roosting ardeids. As
presented in Noise Assessment in Section 3, the noise barrier/ enclosure along the viaduct can mitigate the noise
level from the operation of train to an acceptable level. In consideration of the high efficiency of noise
suppression measures and high tolerance of ardeid to
the traffic noise, the potential ecological impact is evaluated as minor. The noise barrier/enclosure may bring a concern of bird collision.
However, consideration has been given in the design of noise barrier/enclosure
with coloured panels, the birds would perceive it as impassable barrier and
therefore the chance of bird collision is greatly minimized. The high tolerance of night roosting ardeid to traffic noise is
demonstrated at the night roost at
In summary of the flow, if
without mitigation measures and the ardeid remain in the WCH Nullah area for
night roosting, the disturbance impact to the night roost is evaluated as
moderate based on the prediction on behavioral change of the affected ardeids.
The consequence may lead to relocation of the ardeids to other suitable site at
Aberdeen Channel and the ardeids would not be subject to the subsequent
disturbances at operation phase. If the ardeids are unaffected and remain in
the WCH area for night roosting, they would be subject to disturbance at
operation phase which is evaluated as minor in consideration of the efficiency
of the noise suppression measures and high tolerance of the ardeids. All
potential disturbances would only lead to a change of behavior but would
unlikely affect the survival and fecundity of the ardeids. From a conservation
perspective, it would not result in decline in population.
4.6.5.2 Disturbance to the Ardeid Species Foraging at WCH Nullah
Due to the availability of easy accessible food source at Wong Chuk Hang Nullah, ardeids are commonly found at the area. The abundance of ardeids is generally very low due to the moderate levels of pollution, high disturbance from human activities in close distance and the highly modified artificial watercourse. However the number of foraging ardeids would become higher at the lower section of the nullah, i.e. the section at the west of Nam Long Shan Road, during low tide period when the low water level makes the fishes more visible and accessible to predators. Many of the ardeids are prone to disturbance by human activities, especially visual and noise disturbance from the presence of human and vehicles nearby. The construction works in close distance to the lower section of the nullah would cause a disturbance to the foraging ardeids. Noise disturbance arising from worker and construction activities would cause a direct impact on the foraging ardeids. Besides, the uncontrolled sediment run-off and discharge of wastewater entering the nullah would potentially deteriorate the water quality and may cause an adverse impact on the ardeids.
As observed from the ecological survey, the foraging population at the nullah is the same to those foraging at Aberdeen Typhoon Shelter. Selection of foraging site is dependent on the tide level which is related to the availability of prey items in the nullah. If the condition of the nullah is not favorable, i.e. high water level or turbidity, the ardeid would prefer the Aberdeen Typhoon Shelter area for foraging.
As the lower section of the
nullah (west of Nam Long Shan Road) would not be decked over permanently, the
forage opportunity for the ardeids would not be encroached significantly. In
considering the
low abundance of ardeid species in the artificially modified and moderately
polluted habitat and a large area of foraging habitat available at the neighbouring area, the impact imposed on the
medium amount of foraging ardeids at lower section of Wong Chuk Hang Nullah is
evaluated as of low
significance.
4.6.6 Impact on Terrestrial Fauna Species of Conservation Interest
4.6.6.1
The
Most of the bird recorded are
common, except 6 conservation concerned bird species, Black-crowned Night
Heron, Pacific Swift, White-throated Kingfisher, Black Kite, White-bellies Sea
Eagle and Crested Goshawk, which listed as “Rare” in
China Red Data Book were also recorded (Table 2a of
Appendix 4.7).
Streams were also recorded in the
As stated in Section 4.6.2,
it is anticipated that no significant or long lasting ecological impacts at the
Aberdeen Country Park as there would be no direct encroachment on the naturally
habitat. Therefore, the impact on the terrestrial fauna species of conservation
interest is considered of minor significance.
4.6.6.2
Most of the birds recorded there
were commonly found in woodland habitat, including 5 conservation interested
species namely Chinese Pond Heron, Black Kite Milvus migrans, Cattle
Egret Bubulcus ibis, Crested Serpent Eagle and Crested Goshawk, which is
listed as “Rare” in China Red Data Book. All of them are resident, which spend the whole year in
41 butterfly species and 19
dragonfly species were recorded in the area. Most of them are common species
except Baron Euthalia aconthea aditha of local concern and Emerald
Cascader Zygonyx iris insignis of potential global concern (Table 4 and
5 of Appendix 4.7). Baron is commonly found in
woodland while Emerald Cascader is widespread in moderately clean, rapidly
flowing forested streams. Potential global concern species, Short-legged Toad Megophrys
brachykolos and Common Rat Snake Ptyas mucosus of potential regional
concern and listed as “Endangered” under China Red Data Book, were also
recorded (Table 3 of Appendix 4.7).
As stated in Section 4.6.2,
only insignificant disturbance would be caused. Therefore, the potential ecological impact arising from the construction works to
the habitat of the conservation concerned species would be of minor
significance.
4.6.6.3
Wong Chuk Hang Nullah
Part of the degraded woodland
along Wong Chuk Hang Nullah would be cleared for the construction of viaduct.
The degraded woodland was used by ardeid as a night roosting site, while the
nullah was found to be a foraging site of several bird species. Assessment of
the impacts relevant to the roosting and foraging of ardeid at Wong Chuk Hang
Nullah is detailed in Section 4.6.5. Most of the other species recorded
at the nullah and nearby area are common in
Black Kite commonly occurs at
Aberdeen Channel and the adjoining WCH Nullah. The availability of trash fishes
over the channel is the major reason attaching black kite foraging at the area.
Disturbance to the wasteland and nullah in WCH would not affect the species
foraging at the Aberdeen Channel. Similarly, the White-throated Kingfisher was
also found foraging at the Aberdeen Channel side, such that no major impact
arising from the railway construction is expected. Lesser Coucal, despite its
protection status in China Red Data Book, is widespread in shrubland habitat in
4.6.6.4
Ap Lei Chau
The construction of the Project
and associated human activities would cause minor disturbance impact on the
conservation concerned species. However, provided the low ecological value of
the highly artificially modified habitat at Ap Lei Chau, the potential
ecological impact is expected to be of minor significance.
4.6.6.5
Chung Hom Shan
The abandoned bare ground at Chung Hom Shan site would be
transformed into a temporary magazine site. Due to the highly modified landscape, the vegetation
found at the site is low in ecological value. Most of the fauna species found
at the site are common, except Leopard Cat Prionailurus bengalensis and
a few conservation concerned bird species. Leopard Cat is widely distributed in
The construction of the magazine site and the associated human
activities would cause a temporary minor disturbance to the bird residing at neighboring habitat. In
view of the low density of fauna species and low ecological value of the artificial habitat at the proposed site, the
potential ecological impact arising from the construction works would be of
minor significance.
4.6.7 Loss of Habitat for Marine Benthic / Coral Community
4.6.7.1
The construction of the pier foundation of the railway bridge
crossing Aberdeen Channel would cause a minor loss of marine benthic habitat. The
ecological dive survey has found a hard coral species, Oulastrea crispata, in low coverage on hard substrate at the area. Oulastrea crispata is a common species
found throughout
As revealed from the dive survey report and the benthic grab
sampling survey report, the location of the pier foundation would be situated
on a mud and silt substrate. Coral coverage for this kind of habitat is
generally very low and mainly on waste materials such as tyres and wood pieces.
The marine benthic habitat to be lost would be small in size and of low ecological value and therefore the consequent ecological impact is of minor
significance.
4.6.7.2
At
As resulted from the ecological dive survey report in Appendix 4.4, only one common hard coral species, Oulastrea crispata, of low coverage was found at the site. In view of the high commonness and low coverage of the species, the potential impact on the subtidal coral community would be minor.
4.6.8 Loss of Intertidal Habitat
At Telegraph Bay barging point, the large boulders at a small section of sloping seawall would be affected during the construction of the temporary tipping hall over
marine piles which in place on the seabed adjacent to the sloping seawall. The
intertidal area to be affected is small in scale. Referring
to the data collected from literature review and intertidal survey, the
intertidal community potentially affected are mostly common species and of
similar type to any other artificial seawalls in
4.6.9
Disturbance to the Marine Benthic and Coral
Community at
Indirect impacts on water quality would potentially arise from land based construction activities and marine dredging works. Sediment run-off, accidental spillage and discharge of waste flowing into the Aberdeen Channel and Aberdeen Typhoon Shelter would deteriorate the water quality and may indirectly affect the marine ecological resources.
Dredging close to coral areas would lead to greatly increasing the sedimentation rate and suspended solids. The change in water turbidity may affect coral growth, recruitment and resilience or even result in coral mortality (Chan 2005).
As resulted from the ecological dive survey, the only hard coral
species occur at the
The potential impact arising from the marine dredging works at Aberdeen Channel would be minimized by adopting a bridge pier construction method in which a dry confined environment would be created by installing a cofferdam. This construction method of creating a confined and dry environment for sediment dredging/ excavation could minimise the release of contaminant into the water column (further details refer to Water Quality Assessment in Section 5.6). As such, the potential off-site impact to the marine resources at surrounding waters is greatly minimized to acceptable level.
In view of the low coverage of the pollution tolerated hard coral Oulastrea crispata and the
implementation of water quality control measures. The potential adverse impact
on the hard coral community at Aberdeen Channel arising from the marine dredging works is considered as of
minor significance.
Table 4.12: Summary of Evaluation of Potential Ecological Impacts
|
Impact |
Ecological Receivers |
Habitat Quality |
Size / Abundance |
Duration |
Reversibility |
Magnitude |
Unmitigated Impact Severity |
Mitigation Requirement |
|
Habitat
Loss – Project Area (Admiralty to |
No ecological sensitive receivers are identified as only artificial habitats of plantation and developed area are covered |
Low ecological quality |
1.92ha of plantation |
During construction phase for temporary works areas (1.87ha of plantation); During construction and operational phase for areas permanently lost (0.05ha of plantation) |
Irreversible for permanent loss; Reversible for temporary loss |
Moderate |
Minor |
Not required. |
|
Habitat
Loss – Project Area ( |
Woodland habitat is identified as the key ecological sensitive receiver.
|
Habitat quality of these secondary woodlands is moderate. |
4.84ha of woodland; and 2.01ha of degraded woodland |
During construction phase for temporary works areas(4.44ha of woodland and 1.57ha of degraded woodland); During construction and operational phase for areas permanently lost(0.40ha of woodland and 0.44ha of degraded woodland) |
Irreversible for permanent loss; Reversible for temporary loss |
Moderate |
Moderate (Moderate-minor for degraded woodland) |
Yes. Mitigation for impact on woodland is required. The detailed design should minimize the habitat loss during the construction stage as far as possible; Habitat reinstatement should be implemented to mitigate the temporary loss of woodland (include loss of degraded woodland as far as possible); Habitat compensation of woodland area not less than 0.40ha. |
|
Habitat
Loss – Project Area ( |
Woodland habitat is identified as the key ecological sensitive receiver. |
Habitat quality of the secondary woodlands is moderate. |
0.28ha of woodland. 0.15ha of degraded woodland |
During construction phase for temporary works areas (0.25ha of woodland, 0.14ha degraded woodland); During construction and operational phase for areas permanently lost (0.03ha of woodland 0.01ha of degraded woodland) |
Irreversible for permanent loss; Reversible for temporary loss |
Moderate |
Moderate-minor (Minor for degraded woodland) |
Yes. Mitigation for impact on woodland is required. The detailed design should minimize the habitat loss during the construction stage as far as possible; Habitat reinstatement should be implemented to mitigate the temporary loss of woodland (include loss of degraded woodland as far as possible); Habitat compensation of woodland area not less than 0.03ha. |
|
Habitat Loss – Project Area (Magazine Site at Chung Hom Shan) |
Shrubland habitat is the only identified ecological receiver. |
Moderate-low habitat quality. |
1.28ha of shrubland. |
During construction phase (1.28 ha of shrubland.) |
Reversible |
Moderate |
Moderate-minor |
The detailed design should minimize the habitat loss as far as possible during the construction stage; and reinstate the disturbed shrubland as far as possible after the temporary occupation |
|
Habitat
Loss – Project Area (Barging point at |
No ecological sensitive receivers are identified as only artificial habitats of plantation and developed area are covered. |
Low ecological quality |
0.02 ha of plantation |
During construction phase (0.02ha of plantation) |
Reversible |
Moderate |
Minor |
Not required. |
|
Habitat Loss – Project Area (Works Site near Wah Kwai Estate) |
No ecological sensitive receivers are identified as only artificial habitat of wasteland is covered. |
Low ecological quality |
1.41ha of wasteland and developed area |
During construction phase (1.41ha of wasteland and developed area) |
Reversible |
Moderate |
Minor |
Not required. |
|
Removal Impact on Floral Species of Conservation Interest |
A cultivated tree species Ailanthus fordii |
Isolated man-made habitat which fragmented by urban areas; Large interface with urban disturbance |
Two
recorded in areas near |
During construction and operational phase |
Irreversible |
Moderate |
Minor |
No specific ecological mitigation measures are required; but proposed tree works should be regulated by ETWB TCW 3/2006 – Tree Preservation |
|
Removal Impact on Floral Species of Conservation Interest |
A tree species of
conservation interest Aquilaria
sinensis |
Close interface with urban disturbance |
One
in the woodland north of One
on concrete slope north of Two in the woodland south of Nam Long Shan Road; Two in plantation south of Nam Long Shan Road; One in the woodland area south of the Wong Chuk Hang nullah |
During construction and operational phase |
Irreversible |
Moderate |
Moderate-minor |
Yes. In-situ preservation should be considered in all stages as far as possible. Otherwise, transplanting the affected individuals should be carried out if impact is unavoidable. |
|
Removal Impact on Floral Species of Conservation Interest |
A protected tree species Lagerstroemia fordii |
Woodland edge having interface with urban disturbance |
One
inside a woodland north of |
During construction and operational phase |
Irreversible |
Moderate |
Minor |
Yes. In-situ preservation should be considered in all stages as far as possible. Otherwise, transplanting the affected individuals should be carried out if impact is unavoidable. |
|
Removal Impact on Floral Species of Conservation Interest |
A rare tree species Gleditsia australis |
Isolated habitat which fragmented by urban areas; Large interface with urban disturbance |
Three
recorded in the woodland area north of One
on concrete slope north of |
During construction and operational phase |
Irreversible |
Moderate |
Moderate |
Yes. In-situ preservation should be considered in all stages as far as possible. Otherwise, transplanting the affected individuals should be carried out if impact is unavoidable. |
|
Removal Impact on Floral Species of Conservation Interest |
A protected tree species Pavetta hongkongensis |
Woodland edge having interface with urban disturbance |
One
in the woodland area north of |
During construction and operational phase |
Irreversible |
Moderate |
Moderate |
Yes. In-situ preservation should be considered in all stages as far as possible. Otherwise, transplanting the affected individuals should be carried out if impact is unavoidable. |
|
Removal Impact on Floral Species of Conservation Interest |
A rare small herb species Houttuynia cordata |
Isolated habitat which fragmented by urban areas; Large interface with urban disturbance |
One recorded in the degraded woodland area south of Wong Chuk Hang nullah |
During construction and operational phase |
Irreversible |
Moderate |
Moderate |
Yes. In-situ preservation should be considered in all stages as far as possible. Otherwise, transplanting the affected individuals should be carried out if impact is unavoidable. |
|
Habitat Loss – Ardeid
Night Roost |
Ardeid species, mainly Little Egret |
Degraded
|
More than 400 ardeids in winter but only
around 100 in summer |
During construction and operational phase |
Irreversible |
Moderate |
Moderate |
Yes.
Site clearance and tree felling works conducted
only in non-wintering season, March to November inclusive,
to minimize the number of affected ardeids.
Loss of roosting trees would be replanted at adjacent area for provision of
roosting habitat. During operation phase, nullah side will be reinstated with
new planting, which provide a potential night roost for ardeids in long term. |
|
Disturbance to ardeid night roost. |
Mainly ardeid species including Little Egret, Great Egret, Chinese Pond Heron and Black-crowned Night Heron |
Degraded woodland of young age providing a night roosting habitat for ardeid species |
Night roosting population is lower in summer but relatively high in winter |
The impact is temporary and would be ceased after the completion of construction |
Reversible |
Moderate |
Moderate |
Yes. Avoid noisy construction activities at sunset time. |
|
Disturbance to ardeid species foraging at WCH Nullah |
Mainly ardeid species |
The drainage channel is relatively low in ecological value due to the moderate level of pollution, high disturbance from human activities and highly modified artificial habitat. |
A short section of the nullah utilized by generally low abundance of wetland birds. The abundance of birds would become higher in low tide period |
During construction phase |
Reversible |
Moderate |
Minor |
Yes. Noise suppression measures. |
|
Disturbance to fauna species at Chung Hom Shan |
Common fauna species |
Abandoned bare ground. |
Low abundance of fauna |
During construction phase |
Reversible |
Minor |
Minor |
None |
|
Habitat
Loss - marine benthic / coral community
(Aberdeen Channel and |
Low diversity of benthic community and one species of hard coral Oulastrea crispata of low coverage. |
Low quality habitat, highly disturbed by organics matters and wastes |
Small in size; low abundance of benthic community and coral community |
During construction and operational phase |
Irreversible |
Minor |
Minor |
None. |
|
Disturbance to the marine benthic and coral community at Aberdeen Channel |
Low diversity of benthic community and one species of hard coral Oulastrea crispata of low coverage. |
Low quality habitat, highly disturbed by organics matters and wastes |
Low abundance of benthic community and coral community |
During construction phase |
Reversible |
Minor |
Minor |
None |
|
Habitat Loss – Intertidal habitat |
Common intertidal community |
Habitat of low ecological function |
Small in size |
During construction phase |
Reversible |
Minor |
Minor |
None |
4.7 Mitigation of Adverse Environmental Impact
The potential ecological impacts identified in Section 4.6 would be mitigated to the maximum practical extent according to EIAO-TM Annex 16 and EIAO Guidance Note No. 3/2002. Mitigation measures are proposed in this section to avoid, minimize and compensate for the identified ecological impacts in order to reduce the impacts to acceptable levels.
4.7.1 Mitigation for Habitat Loss
4.7.1.1 Minimising Habitat Loss
Although the impact of habitat loss along the proposed alignment is considered not significant due to the limited ecological value of the habitats, effort should be given at the detailed design to minimise the habitat loss particularly woodland as far as possible during the construction stage as woodland habitat requires longer duration for tree planting for habitat restoration. As stated in Section 4.6, impacts of loss of other habitats are considered not significant for their either low ecological value or small size.
4.7.1.2 Habitat Reinstatement for Temporary Habitat Loss
For unavoidable temporary loss of degraded woodland and shrubland, the affected habitats are recommended to be reinstated as far as possible after the completion of works. For the comparatively higher ecological importance of woodland habitats, all the temporarily affected woodland areas should be reinstated to provide a full restoration.
4.7.1.3
Habitat Compensation for
Permanent
As some permanent structures are proposed on existing woodland
areas, permanent loss will occur (i.e. part of the woodland areas along the
Wong Chuk Nullah and north of
As shown in Table 4.11, permanent loss of woodland habitat will be 0.43ha in size. Potential areas to implement habitat compensation of woodland would include the existing shrubland and hillside grassland (Figure 4.11) areas to be temporarily affected during the construction stage. After the temporary occupation of these shrubland and grassland areas, habitat compensation of woodland can be carried out. In order to fully mitigate the permanent woodland loss impact, the habitat compensation should be not less than 0.43ha.
Plant species used for the habitat reinstatement and habitat compensation of woodland habitat could base on those recorded in existing woodlands within the Assessment Area. The following table shows the recommended planting schedule:
Table 4.13: Proposed Planting Schedule for
Habitat Reinstatement / Habitat compensation of
|
Species |
Habit |
Species |
Habit |
|
Celtis sinensis |
Tree |
Aquilaria sinensis |
Tree |
|
Reevesia thyrsoidea |
Tree |
Sterculia lanceolata |
Tree |
|
Schima superba |
Tree |
Litsea rotundifolia |
Shrub |
|
Schefflera heptaphylla |
Tree |
Ilex asprella |
Shrub |
|
Sapium discolour |
Tree |
Rhaphiolepis indica |
Shrub |
|
Mallotus paniculatus |
Tree |
Psychotria rubra |
Shrub |
|
Liquidambar formosana |
Tree |
Rhodomyrtus tomentosa |
Shrub |
As some of the degraded woodland areas currently are intensively covered
by self-seeded invasive weedy plants especially those Leucaena leucocephala in ex-Canadian Hospital site and some areas
along Wong Chuk Hang Nullah, the replacement of these undesirable plants by species native
to natural woodland and shrubland in
4.7.2 Mitigation for Roosting and Foraging Ardeid
4.7.2.1
Mitigation for Loss of Ardeid Night Roost Habitat
During the construction of the viaduct at WCH, the slope enhancement works and site clearance would cause a loss of night roosting habitat for ardeid. The loss of habitat used for ardeid night roost is approximately 20% of the wooded area along the nullah utilized by the ardeid. The roosting ardeid to be affected by the loss of habitat would need to find another alternative new night roost. It would cause impact of moderate significance to the roosting ardeid because a high number of ardeid would be affected. It was observed that the roosting population comprises a large portion of wintering birds in winter which means the site is mainly utilized by migratory population.
Avoidance of sensitive works at peak wintering season could minimize
the affected roosting population. As observed from the night roost survey, the
roosting population decreased gradually from more than 400 in December 2008 to around 100 in 2009 summer. If the pioneer site clearance and tree
felling works can be conducted in non-wintering season, the affected population
would be greatly minimized. After the roosting trees were felled, the ardeid
would settle on other suitable trees nearby for night roosting. When the
majority wintering ardeid arrives, they would follow the residing ardeid to
settle on the relocated night roost and only subject to minor disturbance on behaviour due to the change of roosting
habitat. Site clearance and tree felling works at the existing ardeid night
roost (location refers to Figure 4.15) should only be conducted in between March and November inclusive in any consecutive years. The potential disturbance to the ardeid settling nearby would be
further controlled by demarcating clearly the works area and ensuring good site
practice to avoid unnecessary disturbance to the ardeids during construction
phase. When conducting site clearance works at the
existing ardeid night roost, the area should be inspected to confirm no active
ardeid nest are present. If any
active bird nest is observed, suitably sized buffer area should be established
to minimize human or machinery disturbance until the nest is abandoned.
Besides, the loss of roosting trees would be compensated by
replanting of suitable tree. The compensatory plantation for the loss of ardeid
night roost will be located at the lower course of the WCH Nullah,
approximately 200m to the west of the existing night roost (location refers to Figure 4.15). This location is
regarded as the best available area for compensation due to its close proximity
to water source and to the existing night roost. In fact, the area is
intermittently used by ardeid for stop-over before heading back to the night
roost or foraging at the nullah.
In order to compensate as far as possible the function for ardeid roosting, heavy standard trees will be selected for replanting. The compensation planting will commence upon completion of construction phase and the tree species to be replanted will make reference to those tree species utilized by ardeid listed in Section 2 in Appendix 4.8. During operation phase, nullah side (works area) will be reinstated with new planting (i.e. the recommended habitat reinstatement stated in Section 4.7.1), which provide a potential night roost for ardeids in long term. Therefore, there will be no residual impact in term of loss of ardeid roosting habitat.
By avoiding the most disturbing works at wintering season, the potential impacts would be confined to the behavioural level of a small population of residing population while the large populations of migratory ardeid are mostly unaffected. As such, the potential impact would be evaluated as minor significance after the implementation of mitigation measures.
4.7.2.2
Mitigation for Disturbance to Ardeid Night Roost
Provided that the roosting ardeid population at WCH is only slightly affected by the site clearance and tree felling works after the implementation of mitigation measures, they would likely settle on other trees at the degraded woodland alongside the nullah. The construction activities in close proximity to the night roost would cause disturbance impact to the roosting ardeids. As resulted from literature review and field observation, the ardeids usually return to the night roost start at about an hour before sunset (Voisin 1991 and Sutar 2000). If the noisy construction activities involving the use of PMEs could be avoided at this period of time, the potential disturbance to the night roost returning ardeid can be greatly minimized. Noisy construction activities using PME within the potential ardeid night roost (area refers to Figure 4.15) should be ceased an hour before sunset. The restriction time on construction activities is between 18:00 – 6:00 everyday.
After the combination of avoidance of construction activities at ardeid night roosting time, the potential impact on the night roosting ardeid would be brought down to acceptable level.
4.7.2.3
Mitigation for Disturbance to Ardeid Species Foraging at Wong Chuk Hang
Nullah
A few species of ardeids were found foraging regularly at the lower section of the WCH Nullah. The abundance is relatively low in general but variable along with the tidal level and season. If the whole WCH Nullah is decked over for the construction works, it would cause a loss of foraging habitat for ardeids. On the other hand, the visual and noise disturbance arising form the construction activities together with indirect impact of silt run-off would cause a combinative impact of minor to moderate significance.
As the WCH Nullah at the lower end will not be decked over permanently, loss of foraging habitat for ardeids can be avoided. The ardeids which have adapted to the frequently disturbed artificial environment could be able to keep foraging at the nullah during construction phase and operation phase.
With the implementation of mitigation measures like the containment of silt runoff, the indirect impact through
degradation of water quality would be minimized. As such, the ardeids foraging at the lower section of WCH Nullah will only be slightly affected and the potential impact is not
significant.
4.7.2.4
Mitigation for Disturbance to Ardeid Night Roost at Operation Phase
Based on the prediction that the ardeid roosting at WCH area would
only be slightly affected during construction phase and would continue to use
the degraded woodland beside the nullah for night roost, the operation of the
railway would not cause significant disturbance impact to the night
roosting ardeids nearby. A high tolerance to traffic noise has been shown in other ardeid
night roost in
The noise level during the operation phase would be minimized using acoustic enclosure / barrier along sections of the viaduct. The acoustic enclosure/ barrier would be designed with coloured panels to minimize the chance of bird collision. Also, trees would be replanted after construction alongside the nullah to provide a substrate for roosting. The amenity facilities to be installed near the potential night roost area are suggested to be reduced in area to allow more space for plantation and reduce human activities. The maximizing of plantation area and minimizing of human disturbance to the area could attract more ardeid to roost.
The combinative effect of minimizing noise level and human activities at ardeid night roost area and maximizing plantation area for roosting would greatly mitigate the potential impact to the night roosting ardeids during the operation phase.
4.7.3 Mitigation for Disturbance to Wildlife at Chung Hom Shan Magazine Site
A minor impact to the fauna species would arise from the construction works at the Chung Hom Shan Magazine Site. Potential sources of water pollution during the construction phase include sedimentation from soil excavation, chemical waste from equipment and discharge of waste water.
Mitigation measures to be implemented in the construction phase relate to good site practice, so that all waste is contained on site and removed where necessary. These measures include the containment of silt runoff with the site boundary, appropriate storage of chemicals and chemical waste and the provision of sanitary facilities for on-site workers. For further details, refer to Waste Management in Section 8.
4.7.4
Mitigation for Disturbance to Coral Community at
A minor significant disturbance would arise from the marine dredging works at the pier foundation of the railway bridge crossing Aberdeen Channel. The suspended solid released from dredging works would cause deposition of sediment or contaminated waste material on the marine ecological resources, especially the hard coral species, at nearby. The potential impact would be minimized by adopting a bridge pier construction method in which a cofferdam would be installed to create a confined dredging environment.
Besides, the pollution arises from land-based construction works would be mitigated by good site practice, so that all waste is contained on site and removed when necessary. These measures include the containment of silt runoff within the site boundary, the containment of contaminated soils for removal from the site and appropriate storage of chemicals and chemical waste.
4.7.5 Mitigation for Impact on Floral Species of Conservation Interest
As discussed in Section 4.6, mitigation is recommended for the impact on the plant species of conservation interest Gleditsia australis, Aquilaria sinensis, Lagerstroemia fordii, Pavetta hongkongensis and Houttuynia cordata.
These plants would inevitably be affected by the project as they are all located within the proposed Project Area for different construction works. These plants are recommended to be transplanted to similar or suitable habitats in the vicinity, i.e. woodland, degraded woodland or shrubland, which can be found at areas adjacent to works areas at Nam Fung Road, Nam Long Shan Road, Wong Chuk Hang Nullah and Sham Wan Towers. A detailed transplanting baseline survey on the affected plants of conservation interest within the impacted Project Area would be conducted by a suitably qualified botanist/ ecologist prior to the commencement of construction in individual section and works site to identify and confirm the final reception locations for the transplanted plants. However if opportunity of in-situ preservation is found available during the detailed design or other stages, this option should be considered as a prioritized measure as far as possible.
Given the small number of plants are involved and the implementation of the proposed preservation and transplanting measures, potential impact on the identified floral species of conservation interest is minimal.
For the recorded Ailanthus fordii, as stated in Section 4.6, no specific ecological mitigation measure is required. However, in-situ preservation should be considered in accordance with ETWB TCW 3/2006 – Tree Preservation and other tree treatment should be regulated by this government technical circular.
4.8 Post-mitigation Acceptability of the Project
Table 4.14 summarizes the potential impacts of the project without mitigation, proposed mitigation measures and significance of impact after mitigation. With the implementation of the recommended mitigation measures for the construction and operation phases of the proposed project, no residual ecological impact is anticipated.
Table 4.14: Summary of Potential Ecological Impacts before and after adoption of Mitigation Measures
|
Description of Potential Impact |
Significance of Impact without Mitigation |
Proposed Mitigation |
Significance of Impact after Adoption of Mitigation Measures |
|
Habitat loss ( |
Moderate |
Woodland loss should be minimised as far as possible during the construction stage Habitat reinstatement for temporary loss of woodland Habitat compensation for permanent woodland loss |
Minor |
|
Habitat loss ( |
Moderate-minor |
Woodland loss should be minimised as far as possible during the construction stage Habitat reinstatement for temporary loss of woodland Habitat compensation for permanent woodland loss |
Minor |
|
Habitat loss (Degraded Woodland) at
Project Area ( |
Moderate-minor |
Habitat Reinstatement for temporary loss of degraded woodland as far as possible |
Minor |
|
Habitat loss (Degraded Woodland) at Project Area (Aberdeen Channel to South Horizons) |
Minor |
Habitat Reinstatement for temporary loss of degraded woodland as far as possible |
Negligible |
|
Habitat loss of Shrubland |
Moderate-minor |
Shrubland reinstatement for temporary loss as far as possible |
Minor |
|
Removal Impact on Floral Species of Conservation Interest |
Moderate-minor |
The plants should be preserved in-situ as far as possible. Transplanting the affected individuals to undisturbed habitats if in-situ preservation is impractical. |
Minor |
|
Loss of roosting habitat for Short-nosed Fruit Bat |
Minor |
No mitigation is required. |
Minor |
|
Loss of Ardeid Night Roost |
Moderate |
Loss of roosting trees would be replanted at adjacent area for provision of roosting habitat. The impacts to the roosting ardeid would be minimized by avoiding site clearance and tree felling works at peak wintering season (December to February). During operation phase, nullah side will be reinstated with new planting, which provide a potential night roost for ardeids in long term. |
Minor |
|
Disturbance Impact to Ardeid Night Roost |
Moderate |
Avoidance of construction activities at
late evening (1800 - 0600) when the ardeids
returning to the night roosting site.
Demarcating clearly the works area and ensuring good site practise to avoid
unnecessary disturbance to the ardeids. |
Minor |
|
Disturbance Impact to Ardeid Species foraging at Wong Chuk Hang Nullah |
Minor |
Good site practise during construction phase to avoid pollution of watercourse. Implementation of noise reduction measures to minimize disturbance. |
Minor |
|
Disturbance Impact to Ardeid Night Roost at operation phase. |
Moderate-Low |
Implementation of noise reduction measures
to minimize disturbance and use of coloured panels in the
acoustic enclosure/ barrier to minimize the chance of bird collision. |
Minor |
|
Disturbance impact on offsite habitats ( |
Negligible |
No mitigation required. |
Negligible |
|
Disturbance to Fauna species at Chung Hom Shan Magazine Site |
Minor |
Good site practise to avoid pollution at construction phase. |
Minor |
|
Loss of Marine Benthic and Coral Community
at |
Minor |
No mitigation required. |
Minor |
|
Loss
of Sub-tidal Habitat for Coral Community at |
Minor |
No mitigation required. |
Minor |
|
Disturbance to Marine Benthic and Coral
Community at |
Minor |
Bridge pier construction method in which a cofferdam would be installed to create a confined dredging environment. |
Minor |
|
Disturbance to Marine Benthic and Coral
Community at |
Minor |
Bridge
pier construction method in which a cofferdam would be installed to create a
confined dredging environment. |
Minor
|
4.9
Cumulative Ecological Impact
According to Section 2.10, four concurrent projects including Central Reclamation Phase III,
Wanchai Development Phase II and Central-Wan Chai Bypass, Harbour Area Treatment
Scheme Stage 2A and Hong Kong West Drainage Tunnel are identified. Another project, Shatin to Central Link (SCL) is also proposed by the Project
Proponent. The protection works of SCL at Admiralty will be carried out under
SIL(E) at the time of the ADM construction and thus it is considered that the
cumulative impact from the SCL project had been assessed in this EIA study. Amongst
the four concurrent projects, only “Harbour Area Treatment Scheme” is
identified as having potential impact on terrestrial ecology. With reference to
the EIA report, work areas at
4.10
Evaluation
of Residual Impact
After implementation of full mitigation measures, the potential ecological impact will be brought down to acceptable level and therefore no residual impact is anticipated. Regarding the permanent loss of woodland, no residual impact will be resulted with implementation of the recommended habitat compensation. For the ardeid at WCH Nullah, their foraging opportunity at the nullah would not be significantly affected whilst the loss of roosting trees will be compensated by replanting of suitable tree upon completion of the Project. The presence of the viaduct and operation of railway may not necessarily impose a residual impact on the ardeids as the co-existence of ardeid roost to railway and amenity facilities has been demonstrated in other existing cases in Hong Kong such as the Tung Shing Lei egretry in Kam Tin district, in which the ardeid breeding roost are in close proximity to West Rail Line but no significant impact on the breeding success has been observed.
4.11 Environmental Monitoring and Audit
The ecological impact assessment in the EIA study has evaluated the ecological consequences of the proposed project and concluded that the overall impacts would be of minor significance with the implementation of mitigation measures. The proposed ecological mitigation measures to avoid, minimize and compensate the identified impacts arising from the proposed project should be checked as part of the environmental monitoring and audit programme during the construction phase.
4.11.1 Recommended Mitigation Measures
Mitigation measures were designed in accordance with Annex 16 of the EIAO-TM which states the general policy and guidance in planning of ecological measures. In particular, the following mitigation measures would be implemented during construction phase.
It is recommended that the Contractor should adopt good working practices for controlling air quality, noise and water quality in order to minimise dust, construction noise and site run-off as far as possible. Details of these measures should refer to the EM&A Manual.
Permanent loss of some area of woodland may be resulted for the construction of the railway facilities and buildings. Habitat compensation in full scale in terms of area will be provided to avoid potential residual ecological impact.
All the floral species of conservation interest should be preserved in-situ as far as possible. If in-situ preservation is found impractical, transplanting should be carried out as a mitigation measure to preserve these plants.
When conducting site clearance works at the existing ardeid night roost, the area should be inspected to confirm no active ardeid nest are present. If any active bird nest is observed, suitably sized buffer area should be established to minimize human or machinery disturbance until the nest is abandoned.
Site clearance and tree felling works at the existing ardeid night roost (location refers to Figure 4.15) should only be conducted in between March and November inclusive in any consecutive years. Demarcating clearly the works area and ensuring good site practice to avoid unnecessary disturbance to the ardeids during construction phase.
Noisy construction activities using PME within the potential ardeid night roost (area refers to Figure 4.15) should be ceased an hour before sunset. The restriction time on construction activities is between 18:00 – 6:00 everyday. The status of the night roost should be regularly monitored by ecologist on monthly basis. Further restriction in accordance with Wild Animals Protection Ordinance (Cap. 170) should be applied if ardeid nest is found. If the ardeid night roost is abandoned or relocated to an unaffected area, the restriction on working hour can be ceased. When abandonment or relocation of the night roost is realized, at least 2 additional evening surveys should be conducted to further confirm the status before releasing the restriction. The surveys should be conducted by ecologist knowledgeable about ardeid night roosting behaviour.
4.11.2 Monitoring Requirements
It is recommended that auditing
of these mitigation measures should be carried out periodically. The ardeid night
roost location should be monitored monthly by ecologist during the construction
phase to check the status. The survey should be conducted using point count
method at evening time from 5:30p.m., approximately an hour before sunset, and
last until the nightfall, when the sky turns dark totally. Direct observation
should be made from a vantage point which enables an unobstructed view over the
area.
An Ecological Impact Assessment had been conducted for the proposed project. Ecological surveys were carried out between June 2008 to November 2009 which covered both the wet and dry season.
A total of 12 habitat types were identified within the Assessment Area, including woodland, degraded woodland, plantation, shrubland, marsh, stream, drainage channel, hillside grassland, agricultural land, wasteland, open field and developed area.
No adverse impacts on the Nam Fung Road Woodland SSSI and
Permanent loss of some area of woodland may be resulted for the construction of the railway facilities and buildings. Habitat compensation in full scale in terms of area will be provided to avoid potential residual ecological impact.
The construction of viaduct at WCH would cause an ecological impact to the ardeids foraging and roosting at WCH area through habitat loss and off-site disturbance during construction and operation phase. The potential impacts from loss of habitat would be mitigated by avoiding tree felling activities and site clearance at winter, when a large population of wintering egrets are present, and compensated by replanting of suitable tree species at adjacent area for provision of night roosting trees. The off-site disturbance to the night roosting ardeid would be mitigated by avoiding construction activities using PME near the ardeid night roost in the evening. With the full implementation of the suggested mitigation measures through avoidance, minimization and compensation, the potential impacts to the foraging and roosting ardeid would be brought to acceptable level, in considering that the impact would not bring a significant impact on the survival and reproductive success. The change of behaviour in response to the disturbance would not lead to a decline in population and thereby not considered as significant from a conservation perspective.
Five floral species of conservation interest were recorded within the Project Area: Gleditsia australis, Aquilaria sinensis, Lagerstroemia fordii, Pavetta hongkongensis and Houttuynia cordata. These plants should be considered for In-situ preservation as far as possible to avoid removal impacts.
As only small scaled and mitigated dredging works are involved in the construction of the railway bridge crossing the Aberdeen Channel, no significant adverse impact on marine ecology is anticipated. The marine piling and building of tipping hall for the Telegraph Bay Barging Point are also small in scale and thereby not expected to bring any significant impacts to marine ecology.
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