Urban Forest Assessment in Bangkok, Thailand

Abstract

Urban forest assessments have been implemented in many cities worldwide to evaluate the urban forest structure and function. This study is the first step to institutionalize urban forest assessments in Thailand. Thus, the objective of this study was to conduct a pilot urban forest ecosystem assessment for Thailand, determine the urban forest value, and pilot study the appropriateness of adapting i-Tree Eco in Thailand. A stratified random sampling method was used to collect the field information. All data from 184 sampling plots were analyzed using i- Tree Eco for the urban forest structure, function, and value. The urban forest assessment in Bangkok showed a diverse mixture of 48 tree species. The three most common tree species which contributed 34.1% of total tree population were Polyalthia longifolia Sonn (15.7%), Mangifera indica L. (13.0%), and Pithecellobium dulce (Roxb.) Benth (5.4%). The majority of trees (approximately 70%) were < 23 cm in diameter. Nearly equally numbers of trees were in the ≤ 7.6 cm (24.4%), 7.7-15.2 cm (23.9%) and 15.3-22.9 cm (21.5%) diameter classes. An estimated 2,504,000 trees (S.E. = 408,646) exist in the Bangkok study area and these trees provide an 8.6% canopy cover. These trees store an approximate total of about 310,000 metric tons of carbon ($7,000,000 USD), which represent the equivalent of decreasing the CO2 in the atmosphere by about 16,000 metric tons/year ($370,000 USD). The estimated annual ecosystem service benefits for air pollution removal of PM10, NO2, O3, CO, and SO2 were about $200,000 USD (6.17 million THB). The total pollution removal was estimated at 738 metric tons/year. The greatest effect of pollutant removal in the Bangkok urban forest study area was with particulate matter (PM10) and 418 metric tons removed annually that was approximately half of the calculated value.