UNIVERSITY OF CALIFORNIA RIVERSIDE An Assessment of Ecosystem Services Provided by Public Street Trees in Bangkok, Thailand A Dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Environmental Sciences by Natthanij Soonsawad December 2014 Dissertation Committee: Dr. Roberto Sanchez-Rodriguez, Chairperson Dr. James O. Sickman Dr. Kurt A. Schwabe Copyright by Natthanij Soonsawad 2014 The Dissertation of Natthanij Soonsawad is approved: Committee Chairperson University of California, Riverside ACKNOWLEDGEMETS I would like to express my deepest appreciation to my advisor and dissertation chair, Professor Roberto Sanchez-Rodriguez. He is incredibly kind and has always supported me since my first year at the University of California, Riverside. This dissertation would not have been completed without his patience and generous help. I would like to sincerely thank my committee members, Professor Kurt Schwabe and Professor James Sickman, who provided continuous support through technical assistance and valuable comments. I would like to express my appreciation to Ms. Delores Lucero, who greatly helped me in analyzing stable isotopes of nitrogen and carbon in my leaf samples. I thank Dr. Boonvong Thaiutsa of Kasetsart University, Dr. Nina Basuuk of Cornell University, and Dr. Greg McPherson and Dr. Armando Gonzalez-Caban of the USDA Forest Service, who provided advice on street tree inventory and adjustments of i-Tree model calculations. I also would like to thank the staff at the Department of City Planning, Department of Environment, Traffic and Transportation Department of Bangkok Metropolitan Administration, Pollution Control Department, and the Thai Meteorological Department for kindly providing technical assistance and data to be used in this dissertation. I would like to thank faculty, staff, and graduate student fellows at the University of California, Riverside, Department of Environmental Sciences for their continuous iv support in making me feel that I am not alone being far away from home. I would like to thank Mr. and Mrs. Liebig in generously providing the George and Hilda Liebig Environmental Sciences Summer Fellowships. Lastly, I would like to thank my lovely family: my mother and father for their tremendous support in all aspects of my life, my husband for always being by my side as my best friend, my mentor, and my buddy since the day we met at UC Riverside, and my family in Mexico and in Thailand for spiritually supporting and cheering me on. v To my family …. vi ABSTRACT OF THE DISSERTATION An Assessment of Ecosystem Services Provided by Public Street Trees of Bangkok, Thailand by Natthanij Soonsawad Doctor of Philosophy, Graduate Program in Environmental Sciences University of California, Riverside, December 2014 Professor Roberto Sanchez-Rodriguez, Chairperson This study focuses on the analysis of ecosystem services provided by green spaces in Bangkok, Thailand, as a potential tool to address urban and environmental problems there. The analyses are divided into two parts for achieving two objectives, 1) estimating the magnitude of ecosystem services provided by public street trees, and 2) examining the relationship between stable isotopic data of tree leaves and the environmental quality of Bangkok’s streets. The findings could be used to identify tree management issues and tree species with high potential to mitigate environmental problems through enhancement of the ecosystem service provision. A combination of field inventories, interviews with related stakeholders, stable isotopic analyses, remote sensing, geographic information, and computational models were used in this dissertation. For objective 1, the results indicate that citywide public street trees can provide environmental services, including reducing about sixty-five tons of air pollutants per vii year; reducing 2.11 million m3 of storm water runoff per year; reducing 13,000 tons of CO2 per year; saving 8.29 million kWh of electricity per year; and storing 70,000 tons of carbon throughout the trees’ lifetime. The total annual monetary benefit of these services is about $4.34 million. Interviews with public officials indicate that they have a moderate understanding of the ecosystem services provided by street trees. Major challenges in tree management are lack of personnel, conflicts with street vendors, sidewalk damage, and overhead wire problems. According to the opinions of street vendors, Bangkok Metropolitan Administration (BMA) should increase tree maintenance to reduce damage risks, and to improve tree health conditions. Regarding the objective 2, the findings from studying the relationship of stable isotopic compositions of nitrogen in tree leaves, and factors such as air quality parameters could be useful in tracing air pollution levels, as well as determining which tree species can absorb high amounts of air pollutants. Tree species recommendations based on the two objective findings are: for reduced planting spaces (minimum width 1.2m), trees in the genus Lagerstroemia are highly recommended. For medium and broad sidewalk plantings (minimum width 1.8m), yellow poinciana (Peltophorum pterocarpum) and tamarind (Tamarindus indica) are the recommended species. viii Table of contents CHAPTER 1 INTRODUCTION ............................................................................................................................. 1 1.1 URBAN ECOSYSTEM AND URBANIZATION ........................................................................................................................... 1 1.2 CONCEPTUAL FRAMEWORK IN THE STUDIES OF ECOSYSTEM SERVICES AND THEIR VALUATION .............................. 5 1.3 URBAN GREEN SPACES AS PROVIDERS OF ECOSYSTEM SERVICES ................................................................................... 8 1.3.1 Regulation of local and global climate through carbon dioxide sequestering ................................ 9 1.3.2 Regulation of air quality ..................................................................................................................................... 11 1.3.3 Provision of water drainage systems ............................................................................................................. 12 1.3.4 Provision of sewage treatment ......................................................................................................................... 12 1.3.5 Provision of recreational and cultural values ............................................................................................ 13 1.4 ECOSYSTEM SERVICES IN URBAN AREAS OF DEVELOPING COUNTRIES ......................................................................... 13 1.5 BACKGROUND OF BANGKOK’S URBAN FOREST CONDITIONS AND POLICIES ................................................................ 14 1.6 REFERENCES ......................................................................................................................................................................... 17 CHAPTER 2 RESEARCH DESIGN ................................................................................................................... 25 2.1 STUDY SITE: BANGKOK METROPOLITAN AREA, THAILAND ......................................................................................... 25 2.2 OBJECTIVES ........................................................................................................................................................................... 27 2.3 METHODOLOGICAL FRAMEWORK ...................................................................................................................................... 27 2.3.1 Assessing the potential use of public street trees to provide ecosystem services .......................... 28 Biophysical/ecological assessment ................................................................................................................................................ 28 Economic valuation ............................................................................................................................................................................. 30 Social assessment.................................................................................................................................................................................. 31 2.3.2 Studying to examine the relationship of 15N and 13C of urban street tree leaves and environmental quality variables ................................................................................................................................. 32 Stable isotopes in ecosystem analysis ........................................................................................................................................... 33 Principal component analysis (PCA) ............................................................................................................................................ 34 2.4 REFERENCES ......................................................................................................................................................................... 36 CHAPTER 3 ASSESSMENT OF ECOSYSTEM SERVICES PROVIDED BY PUBLIC STREET TREES IN BANGKOK, THAILAND ................................................................................................................. 42 ABSTRACT ....................................................................................................................................................................................