The Greening, Landscape and Tree Management Group (Management Group) under the Development Council of the Hong Kong Special Administrative Region has commissioned consultants to conduct research and provide guidance for the reorganization and selection of street trees in Hong Kong. The research is based on the principle of "planting trees according to local conditions" and aims to enrich the diversity of tree species, in order to enhance the regulatory power of urban forests in Hong Kong, improve the ecological health of upstream areas, and reduce downstream tree risks.
The trees planted in the past may have been suitable for planting in that location at that time, such as the pioneer trees used for slope afforestation in the early years, which have grown up today and are not compatible with the densely populated urban environment in the surrounding area, or they have reached the end of their lifecycle and become unsuitable. As we gradually need to replace trees, it also provides opportunities for us to apply and practice sustainable landscaping strategies. The study of "Hong Kong Street Ecological Strategy" is carried out for this purpose. The research aims to provide a comprehensive strategic framework for long-term and sustainable street tree planting in Hong Kong, while also supporting the overall work of the government on the Hong Kong Biodiversity Strategy and Action Plan, Hong Kong Climate Action Blueprint 2030+, and Hong Kong 2030+: Planning Vision and Strategy Across 2030. The research includes the development of the Street Tree Selection Guide, which provides practical reference tools for designers to select suitable tree species on various common streets in the urban area of Hong Kong.
The study analyzes and evaluates the current street conditions in Hong Kong, and suggests planting more diverse tree species on different types of streets. The research methods include reviewing current guidelines and regulations, on-site observations, local experiences, and incorporating valuable opinions from the landscape and tree art industry, relevant government departments, and professional associations.
A study has found that the street trees in the current urban area of Hong Kong are mainly 20 common tree species widely planted. This type of planting or single planting mode will weaken plant diversity, making urban forests in Hong Kong more susceptible to pests and diseases, and also leading to a decrease in soil quality. To address this situation, this guide recommends 80 tree species that have been less commonly used but are suitable in the past to support the sustainability, health, and regulatory capacity of our urban forest's long-term development. Users can also choose other suitable tree species that are not included in the list due to the limitations of the scope of this study, including 20 common tree species in urban areas, based on the principles and methods provided in the guide. However, to improve the plant diversity of future urban forests, efforts should be made to minimize the widespread planting of these previously common tree species.
This guide is written for consultants, government officials, professionals, and practitioners engaged in street tree replacement and planting related work. To achieve healthy and adaptable urban forests, we suggest using the 10-20-30 plant diversity basic principles as a starting reference, which means that no more than 10% of any plant variety, no more than 20% of any plant of the same genus, and no more than 30% of any plant of the same family. Due to the unique environmental factors of the roadside planting environment, such as the width of the pedestrian road, distribution of underground facilities, microclimate, air flow, etc., guidelines should not be used as established rules. Professional opinions from landscape architects and other related industries should be sought during the planning and design stages to ensure that the street landscape design and other auxiliary elements have been comprehensively and properly considered, Including "Complementary Vegetation Community Mix", tree hole design, permeable and pressure resistant planting soil or modules, drainage systems, underground facilities, etc.
Suitable trees and plants can thrive in a favorable environment, thereby reducing the need for future care. We encourage designers and departments to widely apply this guide to select and plant suitable tree species when carrying out street tree replacement and planting. Through more practical applications and accumulated experience, we hope to provide timely review and updates to the guidelines in the future. We encourage users to provide feedback to our management team and work together to continuously improve the future urban ecology of Hong Kong.
