CY Jim
Education University of Hong Kong, Department of Social Science, Faculty Member
Resettlement residential areas (RRAs) are a unique product of China’s urbanisation process. Their greening environment is critical to the quality of life and liveable green neighbourhood of the displaced farmers. Our study aimed to (1)... more
Resettlement residential areas (RRAs) are a unique product of China’s urbanisation process. Their greening environment is critical to the quality of life and liveable green neighbourhood of the displaced farmers. Our study aimed to (1) interpret the species composition of the landscape trees and their contributions to urban biodiversity in RRAs, and (2) elucidate the structural changes in the tree composition in the last 20 years. Twenty selected RRAs in Changzhou, Jiangsu Province, China, were divided into three categories by completion year. We assessed tree species composition, floristic diversity, tree dimensions, importance value, RRA characteristics, and greening management. The sampled sites accommodated 741 stems and 52 species belonging to 25 families. The three most abundant species were Cinnamomum camphora, Osmanthus fragrans, and Magnolia grandiflora, constituting 45.75% of all trees. The importance values revealed a changing tree planting pattern over time, with persist...
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ABSTRACT Heritage trees play special ecological, historical and landscape roles in cities. The officially designated old-valuable trees (OVTs) in Hong Kong, threatened by urban intensification and improper care, demand deep understanding... more
ABSTRACT Heritage trees play special ecological, historical and landscape roles in cities. The officially designated old-valuable trees (OVTs) in Hong Kong, threatened by urban intensification and improper care, demand deep understanding to inform management and conservation. This study evaluated their floristic diversity, biomass structure and importance value, and spatial pattern and differentiation by districts and tree-habitats. Data analysis was assisted by detrended correspondence analysis (DCA), similarity percentage analysis (SIMPER) and other statistical tests. New indices, namely district dissimilarity index (DDI), district heterogeneity index (DHI), habitat dissimilarity index (HDI) and habitat heterogeneity index (HHI) helped to assess spatial differentiation. The 352 OVTs belonged to 70 species, 56 genera and 36 families. Ficus microcarpa dominated with maximum importance value, accompanied by only three common species. Some 22 rare and 44 solitary species denote diverse origins due to inheritance and cultivation. Moraceae and Ficus were the dominant family and genus. The oldest districts accommodated more species, trees, and unique species, whereas newer districts had notably less. DCA showed higher floristic fidelity in old districts, and three common Ficus species were ubiquitous in districts. SIMPER results showed the highest DDI and lowest DHI in the newer district. Public park and garden (PPG) habitat harbours most species, trees, and botanical uniqueness. Three Ficus species were also ubiquitous in habitats. Public housing and PPG had the highest HDI. District and habitat dissimilarities were mainly contributed by dominant and common species. Management implications with reference to preservation and enhancement of OVTs were explored, with applications for other cities.
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Context Quantitative information regarding tree species-specific size is an essential tool for landscape planning. It reflects tree-environment and human–environment interactions in the urban landscape. The effects of habitat types on... more
Context Quantitative information regarding tree species-specific size is an essential tool for landscape planning. It reflects tree-environment and human–environment interactions in the urban landscape. The effects of habitat types on tree allometry have seldom been evaluated. Objectives Firstly, to derive size-related information of common urban tree species in Hong Kong. Secondly, to evaluate the effects of habitat types on tree allometry. Methods A database of 28,622 trees was established by a field assessment. The allometric relationships (DBH-height and DBH-crown width relationships), by both OLS regression and quantile regression, and maximum size of 30 common urban tree species, and the effects of five main habitat types on tree allometry were determined. Species were assigned to groups according to dimensional traits by cluster analysis. Results In general, the allometric relationships of height and crown width to DBH were significant and varied among species. The wide prediction intervals of the OLS regression indicated the high uncertainty of allometric relationships in our region. The 99th percentile crown width of most species reached 10 m, hinting the general failure of most habitats to meet the planting space requirement. Only two large-stature species have narrow crowns. Habitat types posed significant but small species-specific effects on tree allometry. Roadside tree pit was a particularly stressful environment. Conclusions Our findings can act as a reference for landscape planning and management in Hong Kong and nearby cities, including species growth space requirement and habitat limitations. However, prediction of height or crown width from DBH must be carefully interpreted in our city.
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Many cities advocate retrofitting green roofs and green walls (GRGW) to create additional green areas, especially in cramped urban areas. Yet, worldwide, only a handful of studies have evaluated the public views towards the benefits and... more
Many cities advocate retrofitting green roofs and green walls (GRGW) to create additional green areas, especially in cramped urban areas. Yet, worldwide, only a handful of studies have evaluated the public views towards the benefits and negative issues and promotion policies of this innovative greening option. To address this gap in the literature, we conducted a survey (N = 500) of residents’ opinions towards GRGW in Tokyo, a city with mandatory installation of GRGW for almost two decades. Respondents mostly agreed with the contribution of GRGW to thermal comfort, air quality, and cityscape but weakly endorsed other potential benefits. High costs as well as mosquitoes and plant litter nuisances were the most recognized negative issues. Mandatory installation was the least preferred promotion policy. Instead, respondents expected installation on public buildings and provision of installation guidance. Respondents predominantly held a “moderate” view towards both the benefits and negative issues, showing indifferent attitudes towards GRGW. Income level and housing type shaped the overall perceptions, whereas age, sex, and current living environment influenced perceptions of individual aspects. Our findings signified a need for a bottom-up strategy to heighten public awareness for the advanced development of GRGW to complement and prime the top-down mandatory installation policy.
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Abstract. Trees on buildings sites are routinely damaged or felled in Hong Kong due to negligence and lax control. In an unprecidented move, the government required the developer of a large well-wooded lot to retain one large Chinese... more
Abstract. Trees on buildings sites are routinely damaged or felled in Hong Kong due to negligence and lax control. In an unprecidented move, the government required the developer of a large well-wooded lot to retain one large Chinese Banyan (Fiscus microcarpa) tree and take necessary measures to en-sure its long-term survival. The size, fine condition, species rarity, longevity and setting justify its preservation. Great costs (about US$120,000) was needed mainly to construct a 18 m diameter and 10m deep reinforced concrete planter in site above five stories of shops and carparks. Routine ar-boricultural inputs, such as phased pruning of crown and roots, installation of aeration and irrigation facilities, and fer-tilization, are prescribed. Special precautions, including regular monitoring of watering and fertilization to minimize risks of physiological stresses, are justified in view of the costly
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Recent rapid urbanization has rendered outdoor space a key quality-of-life factor, yet walkability studies especially in hot-humid climates have seldom considered human biometeorology. This site-level study investigated microclimatic... more
Recent rapid urbanization has rendered outdoor space a key quality-of-life factor, yet walkability studies especially in hot-humid climates have seldom considered human biometeorology. This site-level study investigated microclimatic functions of an overhead structure in improving walkability, and identified biometeorology-related factors influencing pedestrian behaviour. A walkway with overhead tinted glass cover, demarcated into sunny zone and shaded zone, was equipped with hanging aluminium fins. Human thermal sensation was approximated by physiologically equivalent temperature (PET) and universal thermal climate index (UTCI), both closely related to global solar radiation and black-globe temperature. Pedestrian flow was tallied by demographic factors to assess the choice between shaded or sunny zones. Compared with sunny zone, shaded zone slashed maximum global solar radiation by 432 W/m 2 in full effect to achieve 90% solar radiation reduction. The maximum cooling in air and black-globe temperatures reached 0.8 °C and 6.1 °C respectively. The overhead structure imposed minimal effect on wind field in both zones. Contrast in maximum PET and UTCI between the two zones reached 8.2 °C and 5.3 °C respectively. In shaded zone, the dominant biometeorological condition was moderate heat stress or slightly warm sensation in contrast to strong heat stress or warm sensation in sunny zone. An overall preference for shaded zone was detected. Pedestrian gender and age, namely female and elderly, were significantly associated with shaded zone preference. The findings could inspire a biometeorological perspective in understanding walking behaviour and pedestrian-friendly facilities. Biometeorological-sensitive design of artificial shade could improve walkability in urban environment that increasingly demands climate change proofing.
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Selecting suitable species to enhance ecological functions is crucial for improvements in the planning and design of roof greening and in maintaining sustainable urban development, especially in rapidly urbanized areas. Assisted by field... more
Selecting suitable species to enhance ecological functions is crucial for improvements in the planning and design of roof greening and in maintaining sustainable urban development, especially in rapidly urbanized areas. Assisted by field trips to enhance studies, the present project assessed the ecological functions of 207 plant species used for roof greening in Beijing based on their key functional traits. The results indicate that regulating, cultural, supplying, and supporting functions differed significantly among species and families in the study area. Rosaceae species have higher levels of overall ecological functions than other species, and a large number of Compositae species have lower-level functions. Compared to other families, Araliaceae and Nyctaginaceae have higher mean values of cultural and supporting functions and the highest mean overall function value of 37. Ulmaceae, Sapindaceae, Ginkgoaceae, Berberidaceae, and Aceraceae have higher mean regulating, cultural, sup...
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Abstract A census of all existing roadside trees in urban Hong Kong was implemented to collect comprehensive information on site characteristics, growing space, tree structure, and tree defects and disorders. The survey methodology,... more
Abstract A census of all existing roadside trees in urban Hong Kong was implemented to collect comprehensive information on site characteristics, growing space, tree structure, and tree defects and disorders. The survey methodology, emphasizing data quality, uniformity, ...
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The changing mode of urban development through time can bring a varied landscape mosaic accompanied by spatial-temporal differentiation of urban vegetation. Hong Kong as an ultra-compact city generates intense interactions between trees... more
The changing mode of urban development through time can bring a varied landscape mosaic accompanied by spatial-temporal differentiation of urban vegetation. Hong Kong as an ultra-compact city generates intense interactions between trees and urban fabric to highlight urbanization effects on tree communities. The study areas cover public housing estates which accommodate about half of the 7.26 million population. Thirteen site factors related to estate, landform and habitat traits were measured or computed as surrogate urbanization effects. Species composition and diversity of tree communities in 102 estates were assessed by field surveys, including four estate groups: older or newer ones situated respectively in urban core or new towns. They contain 48,823 trees belonging to 232 species with heavy exotic representation. Total tree density and native tree density in newer estates were significantly higher than older ones. Differences in species richness and diversity and native species richness between older and newer estates were not significant, expressing to a certain extent the floristic-homogenization phenomenon. Multi-response Permutation Procedures (MRPP) results showed significant difference in species composition between older and newer estates, which could be explained by variations in development age, density, town plan and pre-urbanization land cover. Nonmetric Multidimensional Scaling (NMDS) results found tree distribution patterns in four estate groups strongly associated with estate area, open space area, estate population, estate age, Shannon index (H′) at planting strip and tree pit, and tree site quality index. Urban-forest management could be improved by adopting more native species and providing high-quality and spacious planting sites to accommodate more and larger trees. The research methods and findings could be used by policy makers and planners in similar large and developing cities to evaluate, design, maintain and enhance urban biodiversity.
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Urban trees, as prominent and pertinent landscape elements of cities, are increasingly studied by both practitioners and academics. Trees in Chinese cities have hitherto received little detailed analysis from the viewpoint of urban... more
Urban trees, as prominent and pertinent landscape elements of cities, are increasingly studied by both practitioners and academics. Trees in Chinese cities have hitherto received little detailed analysis from the viewpoint of urban forestry or landscape analysis. This study attempts a comprehensive evaluation of the tree population in Nanjing, focusing on the association between urban development and treescape attributes. Six
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Research Interests: Environmental Science, Energy Conservation, Power Plant, Soil moisture, Evapotranspiration, and 15 moreAir Conditioning, Green Roof, Energy Saving, Passive Cooling, Heat Flux, Relative Humidity, Thermal Performance, Solar radiation, Forestry Sciences, Air Temperature, Wind Speed, Roof, Heat Loss, surface temperature, and CO Emission
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Research Interests: Engineering, Landscape Ecology, Environmental Management, Ecology, China, and 15 moreLandscape, Urban Development, Network, Planning, Environmental Sciences, Urban form, Case Study, Open Space, Chine, Environmental quality, High Density Concrete, Urban Landscape and Planning, Environmental benefit, urban expansion, and High density
Research Interests: Engineering, Geography, Public Opinion, Natural Resources, Outdoor Recreation, and 15 moreChina, Environmental Sciences, Far East, Face to Face, Contingent valuation, Chine, Cost Benefit Analysis, Natural Capital, Elsevier, Cluster Sampling, Ordered Probit Model, Contingent Valuation Method, Age Groups, Recreational Activity, and Payment Cards
Research Interests: Engineering, Geography, Information Management, Urban Forestry, Urban Ecology, and 15 moreEnvironmental Sciences, Rare species, Nature Conservation, Indicator species, Species Diversity, Species Richness, Urban Green Space, Spatial Pattern, Green Space, Urban Forest, Ecosystem service, Statistical Test, Elsevier, Urban Park, and Tree Species
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ABSTRACT Intensively urbanized Hong Kong has a degraded countryside envelope with 170 years of afforestation history. This study assessed seedling quantity, species composition, native-exotic relativity, and native ecological traits in 30... more
ABSTRACT Intensively urbanized Hong Kong has a degraded countryside envelope with 170 years of afforestation history. This study assessed seedling quantity, species composition, native-exotic relativity, and native ecological traits in 30 years. Data were analysed by cluster analysis, two-way indicator species analysis (TWINSPAN), and principal component analysis (PCA). The plantations received 16.54 million seedlings from 209 species. Seedling profile skewed towards 142 native species (67.9%) and 9.49 million exotic seedlings (57.4%). The dominant species group had three exotic species each with >1 million seedlings. The abundant group of 27 species had contained 19 natives associated with main primary forest components. The 179 species in frequent and rare groups denoted changing and diverse species selection. Analysis of start and truncation times found 50% of natives with ascending trend and 33% of exotics with descending trend. Aggregate ecological value of natives increased progressively. TWINSPAN classified native species into two groups with signature characteristics. PCA revealed scattered distribution of natives by adoption trend, start time, truncation time, and ecological value. Ecological restoration of synergistic-mutualistic associations between native plants and wildlife has gained importance. Potential pioneer and enrichment-planting arboreal species were identified to sustain the afforestation programme. Hong Kong has a rich vascular flora with about 390 native tree species, implying that around 250 native tree species had never been used in afforestation. Large-scale planting trials should be conducted to further refine species choice in future afforestation. The findings could inform afforestation and conservation efforts in Hong Kong and other degraded tropical lands.
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... [20] E. Alexandri, P. Jones, Developing a one-dimensional heat and mass transfer algorithm for describing the effect of green roofs on the built environment: Comparison with experimental results. Building and Environment 42 (2007)... more
... [20] E. Alexandri, P. Jones, Developing a one-dimensional heat and mass transfer algorithm for describing the effect of green roofs on the built environment: Comparison with experimental results. Building and Environment 42 (2007) 2835-2849. ...
Research Interests: Engineering, Environmental Science, Modeling, Comparative Study, Medicine, and 15 moreSeasonality, Evaporative Cooling, Thermal Performance, Lancet, Temperature measurement, Thermal Analysis, Environmental Conditions, Thermal Insulation, Heat Diffusion, Porous Medium, Specific Heat, Abiotic Factor, Theoretical Model, Environmental Problem, and The Lancet
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Green roof, an increasingly common constituent of urban green infrastructure, can provide multiple ecosystem services and mitigate climate-change and urban-heat-island challenges. Its adoption has been beset by a longstanding... more
Green roof, an increasingly common constituent of urban green infrastructure, can provide multiple ecosystem services and mitigate climate-change and urban-heat-island challenges. Its adoption has been beset by a longstanding preconception of attracting urban pests like mosquitoes. As more cities may become vulnerable to emerging and re-emerging mosquito-borne infectious diseases, the knowledge gap needs to be filled. This study gauges the habitat preference of vector mosquitoes for extensive green roofs vis-à-vis positive and negative control sites in an urban setting. Seven sites in a university campus were selected to represent three experimental treatments: green roofs (GR), ground-level blue-green spaces as positive controls (PC), and bare roofs as negative controls (NC). Mosquito-trapping devices were deployed for a year from March 2015 to 2016. Human-biting mosquito species known to transmit infectious diseases in the region were identified and recorded as target species. Generalized linear models evaluated the effects of site type, season, and weather on vector-mosquito abundance. Our model revealed site type as a significant predictor of vector mosquito abundance, with considerably more vector mosquitoes captured in PC than in GR and NC. Vector abundance was higher in NC than in GR, attributed to the occasional presence of water pools in depressions of roofing membrane after rainfall. Our data also demonstrated seasonal differences in abundance. Weather variables were evaluated to assess human-vector contact risks under different weather conditions. Culex quinquefasciatus, a competent vector of diseases including lymphatic filariasis and West Nile fever, could be the most adaptable species. Our analysis demonstrates that green roofs are not particularly preferred by local vector mosquitoes compared to bare roofs and other urban spaces in a humid subtropical setting. The findings call for a better understanding of vector ecology in diverse urban landscapes to improve disease control efficacy amidst surging urbanization and changing climate.
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A compact city is a special urban form with inherent physical, social, and institutional constraints on greenery that obstruct the achievement of sustainability. In this study, Hong Kong is used as a case to assess the constraints and... more
A compact city is a special urban form with inherent physical, social, and institutional constraints on greenery that obstruct the achievement of sustainability. In this study, Hong Kong is used as a case to assess the constraints and challenges related to urban green spaces (UGS) development in compact cities. Strategies to overcome these obstacles and improve the UGS conditions are developed. Opportunities to implement the strategies are then evaluated. Because compact cities have extremely limited space allocated for UGS on the ground level, strategies to optimize the layouts of green spaces and seek additional spaces above or below the ground level, such as vertical green surfaces or structures, green roofs, and podiums, are possible solutions. Measures to implement the strategies are summarized as (1) reorganizing the departments and offices related to UGS and clarifying their individual responsibilities to increase their efficiency; (2) encouraging citizen participation; (3) establishing proper legal basis; (4) forming a comparatively connected comprehensive green network of green sources and green sinks with ground-level green spaces, skyscraper farms, and sky gardens, all with optimal layouts; (5) maintaining and repairing UGS after construction; and (6) selecting species of plants that will thrive in specific green spaces. The compact form of Hong Kong provides many chances to implement these strategies. The study increases understanding of the critical factors behind the success or failure of UGS develop- ment in one of the most compact cities in the world and provides suggestions for strategic and policy-related measures for the provision and management of UGS in other congested areas. DOI: 10.1061/(ASCE)UP.1943-5444.0000076. © 2012 American Society of Civil Engineers.
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Research Interests: Mechanical Engineering, Civil Engineering, Energy, China, Sensitivity Analysis, and 15 morePergamon, Solar Energy, Public Housing, Evapotranspiration, Energy Saving, Energy Balance, Passive Cooling, Heat Flux, Chine, Energy efficient, Interdisciplinary Engineering, Heat Dissipation, Soil Water, Remote Sensing Image, and Latent Heat
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Surveys of urban forests in the compact city environment of Hong Kong were initiated in 1985 and regularly updated thereafter. Roadside trees were evaluated first in a tree census and reported in this article followed by urban parks,... more
Surveys of urban forests in the compact city environment of Hong Kong were initiated in 1985 and regularly updated thereafter. Roadside trees were evaluated first in a tree census and reported in this article followed by urban parks, public housing estates, and special habitats such as old stone walls or special specimens such as heritage trees. The survey method aimed at collecting comprehensive data to echo both tree conditions and tree–environmental interactions. Detailed information was gleaned, with the help of well-trained assistants, on tree sites, tree growing space, tree structure, and tree defects and disorders. A field record form was designed, pilot-tested, and refined to solicit responses to multiple choices or direct measurements to minimize subjectivity and errors in data recording and entry. The study also identified potential planting sites, registering suitability for tree growth, site characteristics, and dimensions. Data fields were designed to be quantitative or...
Research Interests: Geography, Spatial Analysis, Methodology, Community Ecology, Statistical Analysis, and 15 moreEcology, Biodiversity, Survey Methods, Growth, Interactions, Arboriculture, Surveys, Measurement, Forests, Ornamental plants, Species Diversity, Habitats, Forestry Sciences, Large Scale, and Horticultural production
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Abstract Green roofs contribute notably to green building and sustainable city goals. Most studies focused on summer cooling and energy-saving benefits, with little attention on winter warming effect. This study evaluated contributions of... more
Abstract Green roofs contribute notably to green building and sustainable city goals. Most studies focused on summer cooling and energy-saving benefits, with little attention on winter warming effect. This study evaluated contributions of the soil component to winter warming with reference to the thickness and moisture content. In subtropical Wuyishan city, Fujian Province, China, we built three houses as experimental green-roof plots. We adjusted soil thickness, measured moisture content, and monitored their impacts on roof outer surface temperature (ROST) in winter. We designated measured outdoor temperature, relative humidity, solar radiation, wind speed, soil thickness and soil moisture content as independent variables, and ROST as dependent variable. The empirical data were enlisted to establish a neural-network prediction model in conjunction with a genetic algorithm to optimize parameter thresholds and weights. The numerical model successfully predicted winter ROST at different combinations of soil thickness and moisture content and identified the best value for energy-saving performance. The model predicted that the maximum ROST of 13.5 °C was achieved at 20 cm soil thickness and 3.9 % moisture content. The choice of deciduous or evergreen plants could fine-tune soil moisture requirement and improve warming service. The study demonstrated the feasibility of optimizing the green-roof design by adjusting controllable soil variables. The neural-network model could reliably predict ROST under different soil conditions to inform design and management.
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Abstract Thermal modifications by a 1.5 m deep pond on adjacent lawn microclimate on sunny, cloudy, overcast and rainy summer days were investigated in subtropical Hong Kong. Microclimatic parameters at a pondside lawn were monitored and... more
Abstract Thermal modifications by a 1.5 m deep pond on adjacent lawn microclimate on sunny, cloudy, overcast and rainy summer days were investigated in subtropical Hong Kong. Microclimatic parameters at a pondside lawn were monitored and compared to an open lawn and a concrete rooftop (Control), with focus on Universal Thermal Climate Index (UTCI) to investigate thermal comfort. The cooling capability of the studied pond has been ascertained – pondside lawn registered the lowest air temperatures (Ta) in most weather conditions, and mean Ta of sunny daytime at pondside lawn was 0.7 °C cooler than open lawn. Compared to Control, UTCI calculations indicated hotter mean daytime conditions at pondside lawn (−2.3 °C) than open lawn (−3.5 °C) on sunny day. Despite the pond’s ability to lower Ta, the lack of pondside tree shading created worse human heat-stress scenarios than open lawn. Cloudy day displayed lower heat-stress levels, but pondside lawn still recorded the highest frequency of strong heat stress (83.6%). To synergistically resolve the thermal-stress problems and transform pond-induced microclimatic cooling into physiological cooling for humans, deeper and more dynamic waterbodies could be incorporated alongside pondside tree shading and natural surfaces in urban park design.
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Research Interests: Criminology and Security
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Page 1. 9 Opportunities and Alternatives for Enhancing Urban Forests in Compact Cities in Developing Countries CY Jim That cities need to be greened is almost a foregone conclusion, if not de rigueur, for any plans for urban development... more
Page 1. 9 Opportunities and Alternatives for Enhancing Urban Forests in Compact Cities in Developing Countries CY Jim That cities need to be greened is almost a foregone conclusion, if not de rigueur, for any plans for urban development or redevelopment. ...
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... STEVE S. W. XU and C. Y. JIM ABSTRACT. ... Heartfelt thanks are due to Dr. He Guoqiang and Mr. Xiao Yiwen for their support during field trips and to Professor Zhang Jinquan, Mr. Shi Yuan'an, and Mr. He Kejun for... more
... STEVE S. W. XU and C. Y. JIM ABSTRACT. ... Heartfelt thanks are due to Dr. He Guoqiang and Mr. Xiao Yiwen for their support during field trips and to Professor Zhang Jinquan, Mr. Shi Yuan'an, and Mr. He Kejun for suggesting this study of the Shimentai Nature Reserve. %b DR. ...
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ABSTRACT Urban Hong Kong has a unique ruderal habitat in the form of old stoneretaining walls. In 160 years of development, the lack of developable land has required the city authorities to adopt elaborate engineering measures to convert... more
ABSTRACT Urban Hong Kong has a unique ruderal habitat in the form of old stoneretaining walls. In 160 years of development, the lack of developable land has required the city authorities to adopt elaborate engineering measures to convert steep slopes into platforms by cut and fill. Hundreds of stone-retaining walls of various dimensions and designs have been constructed to support the unstable slopes. The rough surface of the walls, the joints between the stone blocks, the soil behind the wall and groundwater seepage have permitted spontaneous plant growth, adding a varied vegetationmantle to these artificial 'cliffs'. Many of the retaining walls have been colonized by large trees, mainly Ficus spp. with a strangler habit, accompanied by shrubs, herbs and animals that formed distinctive landscape and ecological features. Recent engineering reinforcement and urban redevelopment, which are unsympathetic to nature, have brought deleterious modifications to or demolition of the retaining walls. Efforts to protect this natural-cum-cultural asset are beset by the inadequate understanding of the intricate association between walls and vegetation. The study was a systematic assessment of the walls, wall trees, and relationship between them, pinpointing mural attributes that facilitate plant growth on the vertical habitat. The findings could inform management and conservation of a valuable and irreplaceable heritage.
Research Interests: Engineering, Urban Geography, Climate Change, Climate Change Adaptation, Green Infrastructure, and 9 moreEnvironmental Planning and Design, Urban Planning, Stakeholders, Urban And Regional Planning, Environmental Sciences, Urban Parks, Urban Green Open Spaces, Urban greening, and Urban Landscape and Planning
... by urban forests, including the identification of ecosystem services, the intrinsic value embodied in such services, and the methods to assess ... They found that in cold climates, a 30% increase in urban tree cover can reduce winter... more
... by urban forests, including the identification of ecosystem services, the intrinsic value embodied in such services, and the methods to assess ... They found that in cold climates, a 30% increase in urban tree cover can reduce winter heating energy use by ... Biodiversity Conservation ...
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To improve and inform adaptive management efforts for China's urban forests, this chapter focuses on (1) an analysis of the key attributes of the city's tree population, and relates them to selected urban factors that... more
To improve and inform adaptive management efforts for China's urban forests, this chapter focuses on (1) an analysis of the key attributes of the city's tree population, and relates them to selected urban factors that are known determinants of urban tree growth; and (2) an ...
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Research Interests: Plant Ecology, Principal Component Analysis, Ecology, Urban Ecology, Factor analysis, and 15 moreFlora, Habitat, Plant growth, Lichens, Retaining Wall, Trees, Urban Trees, Habitats, Multiple Regression, Vegetation, Introduced species, Forestry Sciences, Woody Plants, Vegetative Growth, and Tree Species
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... Closed House and Insanitary Dwellings Ordinance (additional building controls on height, design, overcrowding and ... 1). This major urban core, at present accommodating 3.5 million people, has been ... In addition, a total of eight... more
... Closed House and Insanitary Dwellings Ordinance (additional building controls on height, design, overcrowding and ... 1). This major urban core, at present accommodating 3.5 million people, has been ... In addition, a total of eight new towns have been developed since the 1970s ...
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Tailored messages are instrumental to climate change communication. Information about the global threat can be... more
Tailored messages are instrumental to climate change communication. Information about the global threat can be 'localised' by demonstrating its linkage with local events. This research ascertains the relationship between climate change attitude and perception of local weather, based on a survey involving 800 Hong Kong citizens. Results indicate that concerns about climate change increase with expectations about the likelihood and impacts of local weather change. Climate change believers attend to all three types of adverse weather events, namely, temperature rises, tropical cyclones and prolonged rains. Climate scepticism, however, is not associated with expectation about prolonged rains. Differential spatial orientations are a possible reason. Global climate change is an unprecedented and distant threat, whereas local rain is a more familiar and localised weather event. Global climate change should be articulated in terms that respect local concerns. Localised framing may be particularly effective for engaging individuals holding positive views about climate change science.
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ABSTRACT Stone retaining walls in urban Hong Kong provided vertical habitats for spontaneous colonization by a diversified humid-tropical flora with large trees. A citywide survey assessed wall and tree characteristics to understand... more
ABSTRACT Stone retaining walls in urban Hong Kong provided vertical habitats for spontaneous colonization by a diversified humid-tropical flora with large trees. A citywide survey assessed wall and tree characteristics to understand wall-tree relationships and identify conservation candidates. Nonparametric correlations were computed between 28 wall attributes versus tree count, tree biomass, and species-vegetation factors. Most of the 245 walls, with 1275 trees, were in residential areas. Moraceae dominated the 30 tree species, predominantly genus Ficus, and especially F. microcarpa. Natives formed the overwhelming majority, largely with pioneer and ruderal traits. The positive effect of adjacent built-up land use and negative effect of wall exposure indicated sheltering from wind could facilitate tree growth. Wall height was a key determinant as taller walls furnished more surfaces free from human disturbance and conducive to seed deposition by frugivorous birds and bats. Stone width offered more horizontal microsites for seeds to lodge. Stone roughness operated at the microscale to encourage nonarboreal vegetation. Joint attributes exerted strong influence on tree growth and less so on nontree affiliates. The walls-cum-vegetation, many older than 100 years, presented a precious natural-cum-cultural heritage, deserving protection as an urban ecological asset.
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Abstract The number and area of nature reserves in China have increased significantly in the last 2 decades. This massive increase has not been matched by a corresponding enhancement of management inputs and capabilities. Six major... more
Abstract The number and area of nature reserves in China have increased significantly in the last 2 decades. This massive increase has not been matched by a corresponding enhancement of management inputs and capabilities. Six major problems in protected ...
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ABSTRACT The study explored the effects of intensive urbanization on urban plant diversity and landscape pattern. An inventory of plant species in managed green spaces in the nine urban districts of Guangzhou (south China) with varied... more
ABSTRACT The study explored the effects of intensive urbanization on urban plant diversity and landscape pattern. An inventory of plant species in managed green spaces in the nine urban districts of Guangzhou (south China) with varied development history was conducted. The relationships among species richness, diversity and urban development were analysed by community ecology attributes, cluster analysis, growth-form differentiation and district fidelity indices, and statistical tests. The 1055 vascular species were dominated by a small number of common evergreen species, accompanied by many rare species. By species richness, tree was the dominant growth form, followed by herb and shrub. Species richness and diversity were slightly below urban-fringe secondary forests. Old and young districts offered disparate conditions for species enrichment to establish urban landscape patterns with divergent floristic and growth-form assemblages. Urban species profile and vegetation landscapes were mainly influenced by planning and management of the urban landscape and changing landscape fashion.
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Research Interests: Real Estate, Engineering, Urban Planning, Housing, China, and 15 moreEnvironmental Sciences, Far East, Nature Conservation, House Prices, Housing Market, Urban Green Space, Chine, Environmental quality, Natural Environment, Green Space, Willingness to Pay, Recreational Activity, Environmental benefit, Hedonic price, and Tropical Zone
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Research Interests: Engineering, Urban Ecology, China, Soil Pollution, Phosphorus, and 14 moreEnvironmental Sciences, Project evaluation, Planting, Soil Fertility, Texture, Soil Compaction, Chine, Soil Structure, Compaction, Soil management, Chemical Properties, Urban Landscape and Planning, Vegetative Growth, and Tropical Zone
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Urban trees in Hong Kong exist in stressful and harsh habitat conditions due mainly to the exceptionally high-density development mode. This study focuses on the cream of the urban tree stock, the heritage trees, which were selected... more
Urban trees in Hong Kong exist in stressful and harsh habitat conditions due mainly to the exceptionally high-density development mode. This study focuses on the cream of the urban tree stock, the heritage trees, which were selected according to five sets of stringent criteria: species, dimension, structure, condition, location, and special considerations. The study area covers the main urban core of the city. The loss of trees in two periods, 1993-1998 and 1999-2003, was monitored, with the predisposing and direct causes of damages ascertained as far as possible. Of the 380 heritage specimens, 54 trees were lost in the survey period. The main predisposing causes were injuries sustained in roadwork and construction activities, both related to root damage and soil disturbance. The principal direct causes were recent gradual decline and abrupt demise due to typhoon breakage. Three pairs of contributing variables registered statistically significant associations (chi(2) test), namely predisposing cause versus direct cause, tree growth form versus direct cause, and survey period versus direct cause. Principal component analysis identified three factors that explained 70% of the variance, namely tree form, tree stature, and growth environment. The main reasons for the high mortality were explored. The possible applications of the findings to improve tree protection and management were discussed in relation to the overall planning for meritorious greenery and green space especially in compact cities.
Research Interests: Urban Forestry, Principal Component Analysis, Environmental Management, Urban Ecology, Population Dynamics, and 15 moreEnvironmental Monitoring, Hong Kong, Multidisciplinary, TIME, Cities, Statistical Significance, Trees, Tree growth, Green Space, Time, Conservation of Natural Resources, Statistics as Topic, cultural characteristics, High density, and Soil Disturbance
Research Interests: Air Quality, Ecosystem Services, Environmental Management, Ecology, Air pollution, and 15 moreChina, Multidisciplinary, Developing Country, Ecosystems, Land Use, Forests, Chine, Green Space, Ecosystem, Ecosystem service, Environment, Air Pollutants, Environmental benefit, Dry Deposition, and Environmental Problem
To optimise the use and management of Hong Kong's country parks, ecotourism has recently been promoted by the government and echoed by the leisure sector.... more
To optimise the use and management of Hong Kong's country parks, ecotourism has recently been promoted by the government and echoed by the leisure sector. Visitors' valuation of ecotourism development hitherto remains scant and could add a new dimension to the knowledge and management base. This study estimated the potential value of ecotourism development using the contingent valuation method (CVM).
Research Interests: Human Geography, Ecotourism, Ecosystem Services, Knowledge, Contingent valuation, and 10 moreDeveloping World, Nature Conservation, Ecosystem service, Willingness to Pay, Protected Area, Natural Resource, Contingent Valuation Method, Public Policy, ENVIRONMENTAL SCIENCE AND MANAGEMENT, and Developing Regions
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... Marine PAs are managed centrally by the National Ocean Agency under the Ministry of ... Government) 1995 Reply concerning consenting to the planning framework of developing forest nature reserve in Guangdong Unpublished letter,... more
... Marine PAs are managed centrally by the National Ocean Agency under the Ministry of ... Government) 1995 Reply concerning consenting to the planning framework of developing forest nature reserve in Guangdong Unpublished letter, Guangdong, China (in Chinese); ...
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Urban Hong Kong is covered by high building, road, and population densities. Its urban morphology is inherently not conducive to extensive or high-grade greening. Recent renewal of old areas has squeezed out some limited interstitial... more
Urban Hong Kong is covered by high building, road, and population densities. Its urban morphology is inherently not conducive to extensive or high-grade greening. Recent renewal of old areas has squeezed out some limited interstitial plantable space, although in new development areas modest spaces have been earmarked for greenery. The study aims at evaluating the major constraints to urban trees and their companion urban soil envelopes and at providing specific recommendations to improve tree management in the city. The analysis covers the above-ground confinements that dampen tree performance, the less tangible but rather difficult institutional restrictions that impose a somewhat unnecessary lid on tree planting, the multiplicity of players and stakeholders involved in urban-tree management that militates against coordination and cooperation, the widespread occupation of underground space by utility lines often to the exclusion of trees, and the extremely poor quality of urban soils that are often used without amelioration to support tree growth. The management recommendations furnish practical suggestions and hints to improve the short- and long-term welfare of trees in terms of quality, quantity, and spatial distribution. The conclusion enumerates some concrete measures for consideration by decision-makers to upgrade the city's greenery to close the gap between science and policy.
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Research Interests: Cultural Heritage, Environmental Management, Environmental Monitoring, China, Multidisciplinary, and 14 moreCities, Humans, Developing Country, Rare species, Life Expectancy, Trees, Urban Trees, Social Conditions, Urban Forest, Environment Design, Management Strategy, Conservation of Natural Resources, Life Span, and cultural characteristics
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Research Interests: Environmental Management, Environmental Monitoring, China, Biodiversity, Logistic Regression, and 15 moreBiodiversity Conservation, Humans, Face to Face, Contingent valuation, Environmental Issues, Economic analysis, Female, Endemic species, Cost Benefit Analysis, BIODIVERSITY LOSS, Economic Value, Conservation of Natural Resources, Logistic Models, Contingent Valuation Method, and Environmental benefit
/ The limited acreage of Hong Kong's urban parks receives a huge number of visitors, imposing a heavy strain on the soil base. Most parks show widespread trampling-induced soil degradation, such as bare patches and compaction.... more
/ The limited acreage of Hong Kong's urban parks receives a huge number of visitors, imposing a heavy strain on the soil base. Most parks show widespread trampling-induced soil degradation, such as bare patches and compaction. These symptoms erode the quality of amenity vegetation and recreational experience. Soil in the most popular park was studied through detailed field and laboratory analysis of six pits denoting different levels of user impacts. Soil profiles show unnatural stratification and poor structure of decomposed granite fill materials used in reclaiming the land from the sea. Marked compaction in surface layers is induced by foot-traffic pressure, with aggregate breakdown and formation of platy structure. Compaction in subsoil layers is inherited from construction damage that persists 40 years after park opening. The predominantly coarse texture has been packed to high bulk densities exceeding the 1.75 Mg/m3 threshold. With diminished porosity, transmission of air and water, storage of plant-available moisture, and root growth suffer. Chemically, the samples have an unnatural alkaline pH; inadequate organic matter, nitrogen, phosphorus, exchangeable cations; and limited cation exchange capacity. The results can help park-soil management, including the need to evaluate soil in planned park sites, salvage high-grade soil parcels, prevent construction damage, ameliorate structure by mechanical operations and suitable amendments, and replace site soil of very poor quality. Edaphic problems can be forestalled or solved by treating soil as an integral component of park planning and management based on scientific principles and methods.KEY WORDS: Urban soil; Urban park; Trampling impact; Soil compaction; Soil management; Hong Kong
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Research Interests: Demography, Economics, Remote Sensing, Migration, Environmental Management, and 15 moreAgriculture, China, Multidisciplinary, Infrastructure Development, Landscape change, Multiple Regression, Resettlement, Government Policy, Field Study, Environmental Impact, Ecological Impact, Conservation of Natural Resources, Large Scale, Environment, and Questionnaire Survey
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Roof greening in cities provides a range of environmental, economic, and social benefits. However, the lack of motivation among property owners in high-rise buildings poses an intractable obstacle to its wide implementation in compact... more
Roof greening in cities provides a range of environmental, economic, and social benefits. However, the lack of motivation among property owners in high-rise buildings poses an intractable obstacle to its wide implementation in compact cities. Cooperation amongst stakeholders, from individual-building to city-block scales, could facilitate adoption of green roofing, with implications for urban sustainability. This study is an attempt to evaluate the net gain from roof greening in terms of apportioned collective costs and benefits to a group of property owners. With government tax exemption to encourage green-roof installation, a fair-allocation scheme, based on the Shapley value, is adopted to distribute the net gain in a partnership structure. A case study in Hong Kong serves to illustrate the application of the method to allocate theoretically the sharable gain of roof greening translated into monetary terms. The results verify the importance of individual owners in different coalition configurations in moulding the benefit profile. The crux of the financial incentive scheme is the enhanced rewards to optimized cooperation, and the pump-priming triggering of cooperation and action. The benefits of green roofs could be maximized by their widespread and contiguous, rather than piecemeal, installation. Green roofs could reduce both capital and recurrent public expenditures in stormwater management, healthcare, and green-space provision, the savings from which would be more than enough to fund the tax-exemption scheme. The findings yield convincing justifications for government financial incentives to promote public – private partnerships and cooperative coalitions of stakeholders in roof greening in compact urban areas.
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... applications ([Holm, 1989], [Bastianoni and Marchettini, 1997], [Dufrene et al., 2005], [Alexandria and Jones ... and to optimize its design to contribute to an eco-friendly urban environment. ... model (TTM) for vertical greenery... more
... applications ([Holm, 1989], [Bastianoni and Marchettini, 1997], [Dufrene et al., 2005], [Alexandria and Jones ... and to optimize its design to contribute to an eco-friendly urban environment. ... model (TTM) for vertical greenery ecosystem to simulate the dynamic heat flux transmission ...
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Green roofs can notably modify the thermal properties of the building envelope and adjacent air to bring environmental benefits. This study investigates the heat flux dynamics of the tropical green roof ecosystem to provide a scientific... more
Green roofs can notably modify the thermal properties of the building envelope and adjacent air to bring environmental benefits. This study investigates the heat flux dynamics of the tropical green roof ecosystem to provide a scientific basis for design and management. Green roof experimental plots were established to monitor the total solar radiation, net radiation, and micrometeorological parameters. The data
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ABSTRACT
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Trees in greenspaces are an indicator of a city’s livability and sustainability. Roadside trees furnish linear greenery that can permeate neighborhoods and serve landscape and amenity functions. They are subject to high-intensity stresses... more
Trees in greenspaces are an indicator of a city’s livability and sustainability. Roadside trees furnish linear greenery that can permeate neighborhoods and serve landscape and amenity functions. They are subject to high-intensity stresses and often perform poorly. Trenching to reach or install utilities along pavements is a major cause of tree damage and subsequent decline. Erroneously, it has been believed
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Abstract The urban landscape is by nature the result of many cultural and natural factors and processes. Cityscape associated with land attributes and human activities expresses a city's social and economic functions. Treescape... more
Abstract The urban landscape is by nature the result of many cultural and natural factors and processes. Cityscape associated with land attributes and human activities expresses a city's social and economic functions. Treescape in the form of species composition, tree ...
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... planned a limited supply of accommodation, golf courses and sports facilities in rural areas. ... view of these recent developments, and in the long-run interest of the environment, it is ... the status of the resource base ¨is-a-¨is... more
... planned a limited supply of accommodation, golf courses and sports facilities in rural areas. ... view of these recent developments, and in the long-run interest of the environment, it is ... the status of the resource base ¨is-a-¨is environmen-` tal planning for future tourism development. ...
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ABSTRACT
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Following a survey of 5000 trees in urban Hong Kong, a systematic species evaluation is presented and discussed. ... Abstract. Following a survey of 5000 trees in urban Hong Kong, a systematic species evaluation is presented and... more
Following a survey of 5000 trees in urban Hong Kong, a systematic species evaluation is presented and discussed. ... Abstract. Following a survey of 5000 trees in urban Hong Kong, a systematic species evaluation is presented and discussed. ...
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Landscape planting programmes sometimes experience decline and failure due to soil problems that are too often neglected. A large-scale planting project in a new town in Hong Kong required a substantial volume of soil which was obtained... more
Landscape planting programmes sometimes experience decline and failure due to soil problems that are too often neglected. A large-scale planting project in a new town in Hong Kong required a substantial volume of soil which was obtained in situ from the fish ponds developed on coastal mudflats. Massive mortality of plants belonging to different growth forms in less than a year suggest a common soil malady. Field and laboratory evaluations of soil and vegetation showed that most plants were afflicted by quick dieback and very poor root growth which was largely confined within the root balls. The stockpiled pond bund soils (PB) had poor physical properties with a silt-loam texture susceptible to structural degradation, compaction, high penetration resistance, restricted aeration and poor drainage. The preparation of a soil mix (SM) by compost and lime amendments provided some relief. The major problem appeared to be the development of extreme acidity (pH 4) due to oxidation of the reduced sulphur triggered by the mechanical manipulation of SM. This would have led to toxic concentration of H and Al and deficiency in nutrient elements. High levels of soluble salts especially accompanied by Cl could also have affected growth. The inherent fertility level and capability to hold nutrients in reserve were limited. Amelioration of PB was considered not cost-effective. The importance of proper soil evaluation to avoid problems in landscape planting is emphasized.
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The rapid rate of development and redevelopment in urban Hong Kong in recent years had extensively damaged or destroyed existing trees. The present legislation and enforcement measures are inadequate to protect natural features in the... more
The rapid rate of development and redevelopment in urban Hong Kong in recent years had extensively damaged or destroyed existing trees. The present legislation and enforcement measures are inadequate to protect natural features in the city. An attempt to identify and ...
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ABSTRACT
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Go to AGRIS search. Arboricultural Journal (1997). Roadside trees in urban Hong Kong: Part III. Tree size and growth space. Jim, CY (Department of Geography and Geology, University ofHong Kong, Pokfulam Road (Hong Kong)). ... Roadside... more
Go to AGRIS search. Arboricultural Journal (1997). Roadside trees in urban Hong Kong: Part III. Tree size and growth space. Jim, CY (Department of Geography and Geology, University ofHong Kong, Pokfulam Road (Hong Kong)). ... Roadside trees in urban Hong Kong: Part IV. ...
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The Three Gorges Project (TGP) in the mountainous middle reach of the Yangtze River entailed large dam construction and farmland inundation by reservoir. Concurrently, national policy mandated defarming and reforesting extensive... more
The Three Gorges Project (TGP) in the mountainous middle reach of the Yangtze River entailed large dam construction and farmland inundation by reservoir. Concurrently, national policy mandated defarming and reforesting extensive erosion-prone slope farmlands in the region. This study evaluated social-ecological impacts of two parallel land-cover change projects on farmland supply, carrying capacity, resettlement, and alternative employment. The integrated research
Research Interests: Human Geography, Remote Sensing, Reforestation, Digital mapping, Land Use, and 11 moreThematic Maps, Land cover change, Yangtze River, High Resolution, Carrying Capacity, Rural Urban Migration, Ecological Impact, Rural Community, Geographic Information System, Questionnaire Survey, and Developing Regions
The leisure sector in Chinese cities has flourished in recent years. Lacking leisure studies could compromise resource supply and management. We explored urban residents’ participation in twenty-five leisure activities in Zhuhai, a newly... more
The leisure sector in Chinese cities has flourished in recent years. Lacking leisure studies could compromise resource supply and management. We explored urban residents’ participation in twenty-five leisure activities in Zhuhai, a newly developed city in south China. Leisure activities were classified into four groups based on consumption venue (intrahome and extrahome) and physical activities (passive and active). A face-to-face
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Sky gardens, a type of above-ground urban green space, have been increasingly welcomed and installed in cities. However, few studies have assessed tree planting, management and health in high-rise greenery. This study investigated tree... more
Sky gardens, a type of above-ground urban green space, have been increasingly welcomed and installed in cities. However, few studies have assessed tree planting, management and health in high-rise greenery. This study investigated tree species composition, planting space design and management, and their relationships with tree health in sky gardens in 15 commercial sky gardens with 480 trees in Hong Kong. We assessed the differences between old and new sites regarding tree species, height, crown diameter, and health. We also evaluated selected planting and management factors, including planter type, distance to neighbor trees, root-growth obstacles, canopy barriers, canopy overlap and topping history. Tree species selection in commercial sky gardens was substantially different from public and private residential green spaces. Older sky gardens had more palm trees by species and tree counts. Newer gardens had increased adoption of broadleaf and conifer species with high ornamental value and compact form but fewer native tree species and lower species diversity. The widely planted Ficus spp. had created long-term management issues. Trees were often densely planted, particularly in newer sky gardens. The common practice of topping indicates poor species selection and mismanagement. Planter types with insufficient growing space had dampened tree health. Our findings reveal the trend of tree species adoption, narrower planting spaces and wider adoption of the sunken planter. Improvements in species selection, growing space design and management practices could promote healthy, stable and safe trees in sky gardens with contributions to biodiversity and other ecosystem services.