BIODIVERSITAS ISSN: 1412-033X Volume 24, Number 3, March 2023 E-ISSN: 2085-4722 Pages: 1908-1915 DOI: 10.13057/biodiv/d240368 Estimation of the aboveground biomass and carbon sequestration in an urban forest remnant using aerial photogrammetry from a low-cost Unmanned Aerial Vehicle CHATCHARIN PENBOON 1,2 , SORAVIS SUPAVETCH 3 , KAMPANART SIRIRUEANG 4 , SASIWIMOL RINNAMANG 4 , PHANUMARD LADPALA 5 , THARNRAT KAEWGRAJANG 6 , PONTHEP MEUNPONG 7, 1 Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand 2 Information and Communication Technology Center, Department of National Parks, Wildlife and Plant Conservation, Bangkok 10900, Thailand 3 Department of Civil Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900, Thailand 4 World Wildlife Fund, Phaya Thai, Bangkok, 10400, Thailand 5 Forest and Plant Conservation Research Office, Department of National Parks, Wildlife and Plant Conservation, Bangkok 10900, Thailand 6 Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand 7 Department of Silviculture, Faculty of Forestry, Kasetsart University. 50 Ngamwongwan Rd, Lat Yao, Chatuchak, Bangkok 10900, Thailand. Tel.: +66- 257-90176, Fax.: +66-294-28107,  email: fforptm@ku.ac.th Manuscript received: 8 February 2023. Revision accepted: 30 March 2023. Abstract. Penboon C, Supavetch S, Sirirueang K, Rinnamang S, Ladpala P, Kaewgrajang T, Meunpong P. 2023. Estimation of the aboveground biomass and carbon sequestration in an urban forest remnant using aerial photogrammetry from a low-cost Unmanned Aerial Vehicle. Biodiversitas 24: 1908-1915. For low-income nations, a low-cost Unmanned Aerial Vehicle (UAV) offers an alternative to the traditional time-intensive forest survey that requires many resources. This study was conducted in the remnant forest with the dominant tree species, Dipterocarpus alatus Roxb., forming the upper canopy. Photogrammetry techniques with UAV images were used to obtain the Canopy Height Model (CHM). The results of tree height, individual tree detection, biomass, and carbon sequestration were compared between ground truthing and photogrammetry estimation. The large percentages of trees were automatically recognized. However, due to a closed forest canopy, some trees might have been left out from the actual count, leading to an undercounting of trees and an underestimation of the aboveground biomass (AGB). The photogrammetric dataset demonstrated a good tree height extraction accuracy and did not differ significantly from that determined by ground truthing (RMSE=2.59 m and 8.24%). The mean predicted height AGB from direct measurement was 24.76 tons ha -1 , higher than those obtained from single- and multi-set photogrammetry, 5.41 and 17.99 tons ha -1 , respectively. AGB and carbon sequestration estimated from photogrammetry were 72.66% of the ground truthing value. The accuracy of the photogrammetry results was acceptable and feasible for detecting individual tree heights, biomass, and carbon sequestration in the remnant forest. Overall, low-cost UAV could create a cost, time-efficient, and reasonably accurate local- scale forest inventory. Keywords: Aerial photogrammetry, precision forestry, remnant forest, single tree segmentation, UAV Abbreviations: aboveground biomass = AGB; canopy height model = CHM; closing and opening filter = COF; diameter at breast height = DBH; digital surface model = DSM; digital terrain model = DTM; Nakhon Chai Bawon = NCB; root mean squared error = RMSE; unmanned aerial vehicle = UAV; structure from motion = SfM; watershed segmentation = WS INTRODUCTION Urban forest remnants are remnants of forest ecosystems with environmental parameters and species compositions similar to historical natural forest benchmarks that are frequently altered by urbanization. (Kowarik and Moritz 2018). Urban forest remnants are biodiversity hotspots, region, or area that contains many different species of plants, animals, and other organisms, many of which are endemic or found nowhere else in the world. These areas are often under threat from human activities, such as habitat destruction or climate change, and conservation efforts are often focused on protecting these hotspots to preserve their unique biodiversity (Han et al. 2019). In urban areas where forests still exist, these small patches of forest can contain a high level of biodiversity, including various tree and animal species. This biodiversity is distributed relatively evenly among the different species present. In other words, even though these urban forest remnants may be small and fragmented, they can still play an important role in preserving and promoting biodiversity within urban environments. In urban areas where forests still exist, these small patches of forest can contain a high level of biodiversity, including various tree and animal species. This biodiversity is distributed relatively evenly among the different species present. In other words, even though these urban forest remnants may be small and fragmented, they can still play an important role in preserving and promoting biodiversity within urban environments. Additionally, such trees can supply