Stone Wall Trees: The Wonder of Vertical Urban Forestry 
香港石牆樹：成就垂直城市林務的遺蹟

Stone Wall Tree (SWT) is a collection of landscape artifact unique to Hong Kong’s geomorphology, urban density and climate. It refers to a series of trees grown on the vertical surface of historical masonry stone walls, built with traditional Chinese wall-making techniques which have already been lost. These trees are of high historical and cultural value, as they symbolize a series of colonial landscape transformation since 1840s, and shaped local community development.

According to a tree survey carried out by Professor C.Y. Jim in 1998, a total of 1275 trees were found growing on more than 500 stone walls. Among them, 30 wall tree species were recorded where 8 species of Moraceae (Mulberry family) dominate the population (88%). A single Moraceae species, Ficus microcarpa or Chinese Banyan, makes almost half the population.

This project outlines the development timeline of SWTs from Colonial Hong Kong, and the more recent local controversies after multiple disputes on SWT felling. It is time for landscape architects and designers to step in and address the current conditions of SWTs with a more comprehensive reading –

(1) to document and study SWTs through the making of drawings alongside the quantitative analysis carried out in the past;
(2) to engage residents in realizing the cultural significance of SWTs in each and every local community; and
(3) to provide a range of design options for the discussion of our future urban landscape among all stakeholders.

This project is awarded the Penny White Project Fund of the Department of Landscape Architecture at Harvard Graduate School of Design in 2018, and received the Honor Awards in the Communication Category in the 2019 American Society of Landscape Architects Student Awards, and Merit Award in the 2020 Boston Society of Landscape Architects Awards.

石牆樹是由香港地貌、城市密度和氣候所孕育的獨有都市地景，指的是一系列生長在歷史悠久的石砌擋土牆垂直表面上的樹木。這些樹木見證著香港自殖民時代以來的地景變化，塑造了各個本土社區的發展，加上石砌擋土牆的技術建造已經失傳，石牆樹都市地景具有極高的歷史和文化價值。

根據學者詹志勇教授在1998年進行的樹木調查，當時發現了總共1275棵樹，生長在500多道石牆上，當中更錄得30種樹種——其中桑科（桑樹科）佔88%，而細葉榕在桑科中佔將近一半。「香港石牆樹」概述了石牆樹百多年來的發展時序，以及記錄近年多個砍伐石牆樹的爭議事件，作者以園境師角色切入，旨在為當前狀況，向公眾提供更全面地的理解，並達至以下主要目標:

（1）通過多媒體及質化分析來記錄石牆樹；

（2）讓地方社區及居民參與其中，擴大對石牆樹背後的文化意義之了解；以及

（3）為所有持分者提供一系列設計方案，推動未來香港城市地景的討論。

項目於2018年獲哈佛大學設計研究院園景建築系Penny White Project Fund贊助，並奪得2019年美國園境師學會學生獎傳訊類榮譽獎及2020年波士頓園境師學會學生獎。