Abstract
Urban forests are dynamic ecosystems that provide environmental services such as clean air and water. The function and benefits of urban forest including cool cities and save energy; improve air quality; strengthen quality of place and local economies; reduce storm water runoff; improve social connections; complement smart growth; and create walkable communities. However there was few ecological study about urban forests in Taiwan. The environmental benefits associated with the urban forest, such as carbon sequestration and air quality improvement, have a value to society. As trees often provide benefits that reduce external costs to society (e.g., air pollution), estimates of these external costs (externality costs) should be applied to the trees. Thus, we conducted this research for improving the management practices to enhance the benefit of urban forests in Taiwan.