Old stone walls as an ecological habitat for urban trees in Hong Kong

1998 ◽  
Vol 42 (1) ◽  
pp. 29-43 ◽  
Author(s):  
C.Y Jim
Keyword(s):  
Hong Kong ◽  
Urban Trees ◽  
Ecological Habitat ◽  
Stone Walls

scholarly journals 3D MAP SYSTEM FOR TREE MONITORING IN HONG KONG USING GOOGLE STREET VIEW IMAGERY AND DEEP LEARNING

2020 ◽  
Vol V-3-2020 ◽  
pp. 765-772
Author(s):  
M. Li ◽  
W. Yao
Keyword(s):  
Hong Kong ◽  
Public Awareness ◽  
Urban Trees ◽  
Depth Image ◽  
Accurate Information ◽  
Ground Truth Data ◽  
Google Street View ◽  
Urban Tree ◽  
Tree Detection ◽  
Street View

Abstract. In densely built urban areas such as Hong Kong, the positive effect of urban trees is to help maintain high environmental and social sustainability for the city while unmanaged trees lead to negative effects such as accidents, outbreaks of pests and diseases. The public awareness of urban tree population has been increasing and preserving all the benefits offered by trees, a continuous monitoring concept would be required. In this work, an efficient 3D map system for tree inventory in Hong Kong is presented to the based on automated tree detection from publicly available Google street view (GSV) panorama images. First, Convolutional Neural Networks (CNNs) based object detector and classifier – YOLOv3 with pretrained model is adopted to learn GSV images to detect tree objects. GSV depth image has been utilized to decode depth values of each GSV panorama image and will provide accurate information to calculate the tree geographic position. A “field of view” filter was designed to remove duplicated tree detection within the overlapped areas followed by spatial clustering applied to further increase the tree localization accuracy. The average distance between the detected trees and ground truth data was achieved within 3 meters for selected roads used for the experiment. Second, a 3D Map platform prototype for facilitating the urban tree monitoring and management was developed. Currently, there is no true 3D platform for interpreting the results of tree records in Hong Kong city areas. With the help of webGL technology, contemporary browsers are able to show 3D buildings, terrain and other scene components together with the obtained tree records in an open source 3D GIS platform, the level of visualization is enhanced as all the detected trees are placed on the 3D digital terrain model. Consequently, it is easy for end-users to know the actual position of the trees and their distribution.

Allometry of urban trees in subtropical Hong Kong and effects of habitat types

2020 ◽  
Vol 35 (5) ◽  
pp. 1143-1160
Author(s):  
L. C. Hui ◽  
C. Y. Jim ◽  
Hao Zhang
Keyword(s):  
Hong Kong ◽  
Urban Trees ◽  
Habitat Types

scholarly journals Impacts of intensive urbanization on trees in Hong Kong

1998 ◽  
Vol 25 (2) ◽  
pp. 146-159 ◽  
Author(s):  
CHI YUNG JIM
Keyword(s):  
Hong Kong ◽  
Road Construction ◽  
Ground Level ◽  
Telecommunication Networks ◽  
Physical Constraints ◽  
Lower Priority ◽  
Urban Impacts ◽  
Large Trees ◽  
Underground Utilities ◽  
Stone Walls

Trees in cities face a severe limitation of plantable space and an exceptionally stressful growing environment. In Hong Kong, shortage of developable land has relegated trees to a lower priority and intensified urban impacts on them, relative to other cities. The vicissitudes of urban growth and trees since the founding of Hong Kong are reviewed, and eleven specific conflicts between urbanization and trees in Hong Kong are described. Redevelopment of existing buildings has raised site coverage by impervious surface and taken away ground-level planting space within and around affected lots. Infilling of relatively low-density areas mainly for government and institutional land-uses has increased development density and removed existing greenery and planting spaces. Road construction and improvement has widely damaged roadside trees and removed valuable and conspicuous greenery. Proliferation of underground utilities has fuelled the contest for usable space and precluded planting in many places. Widespread and frequent roadside trenching, associated with utilities and the laying of cable television and telecommunication networks has incurred massive root damage at roadsides. Poor soil quality commonly beset by chemical and physical constraints has caused chronic poor tree performance. Intrusion into urban parks and other green enclaves by buildings and roads has usurped the limited stock of green spaces. Encroachment into peri-urban woodlands has deprived the city of fringing mature greenery with conservation, landscape and amenity worth. Plantable space in reclaimed lands has been intensively used with inadequate allocation for trees. Protection and preservation of champion specimens has lacked statutory means and a coordinated policy. Reinforcement and demolition of stone walls has destroyed many large trees on unique mural habitats. Quality of arboricultural practice is poor, particularly in the private sector. Possible solutions to these limitations in Hong Kong are suggested, and have implications for other cities facing similar problems.

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