Hong Kong International Urban Forestry Conference 2020 ... · Hong Kong International Urban...
Transcript of Hong Kong International Urban Forestry Conference 2020 ... · Hong Kong International Urban...
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1Landscape DivisionHighways Department
Hong Kong International Urban Forestry Conference 2020
Acacia Management and BeyondKathy Ng Chief Landscape Architect MLA MSc FHKILA RLA ISA CA ISA TRAQ HKIUD BEAM Pro17 January 2020
This is an abridged version of the original presentation.
Approval from Highways Department (and the original source of photos) have to be obtained for any form of copying, reprinting and reproducing.
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Government Trees - Urban Areas(exclude Country Parks)
HighwaysDepartment(HyD)
LCSD
around 1.7 million
0.60 M(35%)
ArchSD, WSD, DSD, HD & Others
HyDAround 150 nos.
Stonewall Trees Other departments
.
Note: 1. Data as at March 20192. Source : Controlling Officer’s reply examination of estimates of expenditure, 2018-19, for Special Finance Committee
Chart1
HyD
LCSD
Others
欄1
0.63
0.51
0.53
工作表1
欄2欄1
HyD0.63
LCSD0.51
Others0.53
若要調整圖表資料範圍的大小,請拖曳範圍的右下角。
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11 km²
Expressways
(total open space in HK - 25 km2)
Slopes
over 10000
HyD SIMAR slopes
+
Highways Department
Chart1
工作表1
欄2欄1
HyD50
LCSD, HD & Others50
若要調整圖表資料範圍的大小,請拖曳範圍的右下角。
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Urban Forestry
cultivation and management of trees … physiological, sociological and economic well-being of urban society… (Jorgensen, 1970)
…multi-managerial system… wildlife habitats, outdoor recreation opportunities, landscape design, recycling of municipal waste… (Society of American Foresters, 1974)
…longer-term policies and plans for urban tree resources, and is connected to different sectors…
…multidisciplinary …participatory (Konijnendijk et al, 2005)
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AcaciaStonewall Trees
Aging trees under stress Eucalyptus
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Background – Acacia
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The Ecology and Biodiversity of Hong Kong (Dudgeon, Corlett, 2004) 7
1950s 2010s Near future
Background - Life cycle of Acacia confusa (台灣相思)
Acacia plantation scheme Senescent stage
• life expectancy is about 50 years
• Health or structural condition of Acacia decline faster at sites with poorer growing condition with shorter life expectancy
• soil erosion control/ vegetation cover
• slope stabilization
• improvement of the fertility of soil
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Senescent Acacia
May 2018
June 2018
- heavy leaning and poor self-correction
- poor stem taper and high height-to-diameter ratios
- high susceptibility to wind thrown
Declined structural stability
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Deteriorating health
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- high susceptibility to drought, soil compaction and secondary pathogens when injury occurs
Senescent Acacia
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Low ecological value- exotic species, not provide appropriate fruits for local wildlife
- hinder the natural propagation and growth of native plants - reduction of light, moisture, nutrients and space
- allelopathy
- decline in one-go
Senescent Acacia
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Note* Seven typhoons were recorded in 2013 (when compared with four to five in other years) The heaviest annual rainfall record was recorded in 2013 (among 2010 – 2015).
(Source: HyD) Year
HyD’s Maintenance Record on Acacia Removal
35% of all reported tree failure cases - Acacia (Tree Management Office, November 2012)11
Background – Acacia
284 341443
892721
808 863 824
1282
0
200
400
600
800
1000
1200
1400
2010 2011 2012 2013 2014 2015 2016 2017 2018
No. of Acacia trees
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Objectives
Public Safety Sustainability Biodiversity
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Programme Workflow
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1 Planning Ahead
• academia• overseas + local tree experts• Tree Management Office• District Council + public
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Apple Daily News
2 Prioritization of Risk and Work
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Acacia tree group survey formPrioritization
Total score
(Moderate priority)
(50-75分)
(Lower priority)(75分)
1.目標評估(Target rating)
2.倒塌風險(Failure potential)
3.樹木大小(Tree size)
4.場地狀況(Site conditions)
5.場地紀錄(Site sensitivity)
Total score 100
2 Prioritization of Risk and Work
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3 Implementation
17GEO Technical Guidelines on Landscape Treatment for Slopes
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Ilex asprella(梅葉冬青)
Psychotria serpens(蔓九節 )
Psychotria asiatica(山大刀)
Diospyros vaccinioides(小果柿)
Litsea rotundifolia(豺皮樟)
Mallotus paniculatus(白楸)
Sterculia lanceolata(假蘋婆)
Litsea glutinosa(潺槁樹)
Microcos nervosa (布渣葉)
Native trees
Native shrubs and ground covers
Tsing Nam Road, Tsing Yi
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3 Implementation
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Native Planting Schedule (Sample)
Chinese Name Botanical Name Spacing(mm)Trees 餘甘子 Phyllanthus emblica 5000
潤楠 Machilus spp. 5000
豆梨 Pyrus calleryana 5000
桑樹 Morus alba 5000
小果鐵冬青 Ilex rotunda var. microcarpa 5000
假蘋婆 Sterculia lanceolata 5000
大頭茶 Gordonia axillaris 3500Shrubs梅葉冬青 Ilex asprella 500
車輪梅 Rhaphiolepis indica 300
崗菍 Rhodomytus tomentosa 300
野牡丹 Melastoma malabathricum 300
九節 (山大刀) Psychotria asiatica 300
朱砂根 Ardisia crenata 300
梔子 (白蟾) Gardenia jasminoides 300Ground cover腎蕨 Nephrolepis auriculata 200Climber薜荔 Ficus pumila -
Note* Trees in small size (e.g. whips/ light standard trees) will be used to minimize the rootpruning and cost for planting on site
Biodiversity Enhancement
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3 Implementation
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Wong Tai SinPui Man Street
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3 Implementation – Pilot Scheme
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ShatinYuen Chau Kok
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3 Implementation – Pilot Scheme
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4 Reuse • Upcycling
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4 Reuse • Upcycling
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5 Monitoring, Evaluation and Enhancement
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中環蛺蝶Neptis hylas.
珍貴嫵灰蝶Udara dilecta
報喜斑粉蝶Delias pasithoe
蛇目褐蜆蝶Abisara echerius
美鳳蝶Papilio memnon
銀線灰蝶Spindasis lohita
鈕灰蝶Acytolepis puspa
檀方粉蝶Dercas verhuelli
黑邊裙弄蝶Tagiades menaka
白弄蝶Abraximorpha davidii
斑鳳蝶幼蟲Larva of Chilasa clytia
古樓娜灰蝶Nacaduba kurava
白腰文鳥Lonchura striata
珠頸斑鳩Spilopelia chinensis
紅耳鵯Pycnonotus jocosus
戈芬氏鳳頭鸚鵡Cacatua goffiniana
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5 Monitoring, Evaluation and Enhancement
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5 Monitoring, Evaluation and Enhancement
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Environmental Performance Evaluation and Pathological Assessment of Acacia Slopes
Objectives
• management measures to reduce Acacia failure
• long-term maintenance plan
• strategic replacement planting design
• suitable replacement planting matrix for sustainable management
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5 Research
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Pathological Assessment• Develop sets of parameters for evaluating Acacia slopes→ Determine the needs and priorities for removal of Acacia trees
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5 Research
Soil Properties Assessment• Collect soil samples→ Analysis and compare data collected from pre-replacement period to post-replacement period
Bird, insect and spider Survey• Conduct surveys on species, biological community found on site→ Determine the effects of replanting on biodiversity at study sites
Microclimate and air quality Assessment• Carbon uptake• Transpirative cooling• Air pollutant update• Air pollutant formation
→ Estimate air quality and climatic effects before and after replanting
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6 Community Outreach
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Community
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Community Bonding
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Community
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Community Bonding
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Community Bonding
Saw millWood dryer
Correctional Services Department Wood workshop
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Community
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Community Bonding
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Community Bonding
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Ecological Corridor Enhancement
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Slopes as the ecological corridor - re-connect community + habitatsExisting greenery
HyD Registered Slopes
Node of connection
Mapping of greenery area and HyD SIMAR slopes in Tseung Kwan O
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Seasonal distribution, size and type of fruits
(Source: Hong Kong Wildtracks, HKBU library)
Examples of bird species in Tseung Kwan O District
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Wildlife habitats + major flows of pedestrians and cyclists
Blow-up Scenario 1 -Tunnel junction
Blow-up Scenario 2 –Along cycling and pedestrian path
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Site photos of existing situation
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Managing large tree quantity + aging treesover 80% tree over 5m
Proactive Urban Forestry Management- new technology –satellite/aerial photos, VIS, MMS, UAV, LiDAR
• inspection• data collection• analysis • proactive measures• feedback + monitoring
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UAV inspection of Eucalyptus Tuen Mun Road
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Tree Location Survey
Tree Attribute
Survey
Tree Tagging Service
Tree Database
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Trial Application
January 2017
March 2018
Tree Health Tracking
January 2017
March 2018
Tree Health Tracking
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Ultimate Goal
MULTISPECTRAL IMAGESLiDARHYPERSPECTRAL SIGNATURE
AI EARLY WARNINGSYSTEM
HEALTH
DETECTION
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Vision
46Thank you
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