Dr. Tan Puay Yok is an Associate Professor in the Department of Architecture in the School of Design and Environment of the National University of Singapore. He obtained his PhD from Cornell University and his academic training was in horticulture science and plant physiology. His research, teaching and professional activities focus on the science, policies, and practices of urban greening and ecology of the built environment. He combines his background in the sciences, experience in urban governance from the public sector, and interactions with practitioners to apply knowledge for urban greening to improve environmental quality and societal well-being. He is active in international collaborations, grant reviews and serves as editorial board member in a number of international journals.  He also advises on landscape design and planning projects in the region as means of transferring knowledge from the academia to practice.  Professor Jim Chi Yung obtained his PhD inagricultural soil science from the University of Reading, UK. He then studied at the US Geological Survey in Golden (Colorado School of Mines) for a Certificate in Hydrology. He is the Chair Professor in Geography at the University of Hong Kong since 2000, and served in the past as Head of Department of Geography and Dean of Faculty of Arts. His research revolves around the core theme of nature-in-city, which encompasses urban ecology, urban forestry, urban greening, urban soil science, green roof, green wall (vertical greening), and urban nature conservation. Adopting an interdisciplinary approach with an emphasis on compact and south cities, he focuses geographically on Hong Kong and other Chinese cities. He has extended his research findings to promoting good policies and practices on urban greening in Hong Kong, including tree planting, green roof, green wall, and nature conservation under the shadow of urbanization.