Evaluation of ecosystem services of rooftop gardens in Dhaka, Bangladesh

Abstract

Urbanization is continually taking place in the cities. Dhaka, Bangladesh's capital and the world's 11th largest megacity, is no exception to this trend. Cities relying on natural ecosystems outside the city boundaries also benefit from internal urban ecosystems as well. Rooftop gardens have the potential to be excellent urban ecosystem stimulators and play a significant role in urban landscape planning and management. An experimental survey was conducted on twenty rooftop gardens from two metropolitan areas (Mohammadpur and Dhanmondi) of Dhaka city. The goal was to examine the four categories of ecosystem services: Provisioning, supporting, regulating and cultural, supplied by ecosystems within the Rooftop Gardens (RTGs) and to evaluate their performances by examining through a Rapid Assessment Checklist (RAC) tool. The RAC was consisted of 47 proxy indicators (33 qualitative and 14 quantitative indicators) directly or indirectly representing various dimensions of ecosystem services. From a maximum of 100, the average score of total ecosystem services was 50 ± 12 which could be considered as an intermediate performance in ecosystem services provision. The highest score 60 ± 14 was obtained from the cultural services and the lowest score 41 ± 13 was from provisioning services. The assessment of RTGES would allow stakeholders to identify the weak and strong points of the existing rooftop gardens for their management and improvement. A proper understanding of RTGES and integrated participation of gardeners and urban planners could contribute to designing ecosystem service based roof gardens for making human settlements ecologically sustainable.