Bin Fisol, M.A.

Dahdouh-Guebas, F.

De Cannière, C.

Lucas, R.

Otero, V.

Saliu, I.S.

Satyanarayana, B.

Wolswijk, G.

Open Marine Archive

137 
Poster presentation Competition poster 
The forester, the form and the geometer: An accuracy analysis of 
mangrove tree heights measured using forestry techniques, UAVs and 
hypsometers  
Saliu Ibrahim Sunkanmi1, Dahdouh-Guebas Farid1,2, Satyanarayana Behara1,3, Wolswijk Giovanna1, 
Lucas Richard4, De Cannière Charles1, Otero Viviana1 and Bin Fisol Muhammad Amir3 
1  Université Libre de Bruxelles, Laboratoire d'Écologie des Systèmes et Gestion des Ressources 
(ULB), Avenue F.D. Roosevelt 50, CP 169, 1050 Brussel, Belgium 
 E-mail: ibrahimsaliu297@gmail.com 
2  Mangrove Management Group (VUB-MMG), c/o Laboratory of General Botany and Nature 
Management, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium 
3  Mangrove Research Unit, Institute of Oceanography and Environment (INOS) Universiti 
Malaysia Terengganu (UMT), 21030 Kuala Terengganu, Malaysia  
4  Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences 
University of New South Wales, Kensington, Australia  
 
Tree height is a fundamental measurement in forest inventory studies and a critical variable for 
the assessment of vegetation biomass, carbon stock and site productivity that authorities use in 
decision-making. However, measuring tree height is often a challenging task, especially in the 
mangroves, and may generate significant errors. Mangroves are one of the most productive 
ecosystems in many tropical and subtropical coastlines. Irregular forms of trees in these 
intertidal forests pose a major challenge to measuring structural parameters necessary for 
evaluating its status. This study conducted an accuracy analysis of tree height estimation 
through different methods ranging from traditional (thumb rule and pole) to geometric and 
trigonometric equipment (SUUNTO clinometer, Nikon 550 laser rangefinder, Blume-Leiss 60 
altimeter), and advanced technologies (Unmanned Aerial Vehicle or UAV – DJI Phantom 3 
professional, Leica distometer). These measurements were carried out in natural and urban 
vegetation settings (mangrove vegetation at Matang as closed canopy and on UMT campus as 
open canopy). In total, 173 mangrove trees (open canopy-146; close canopy-54) were measured 
from the both sites and grouped into different stem diameter size classes (0-20 cm, 20-40 cm 
and 40-60 cm). Height measurements obtained from the Leica distometer were considered as 
control. This was achieved by shooting the Leica distometer at a UAV flying at the tree’s canopy 
level. 
 
Using percentage errors, our results show that height measurements obtained from the DJI 
drone (3.5%), rangefinder (7.1%), pole (7.4%), altimeter (7.5%), clinometer (7.7%), stick method 
(14.8%) and thumb rule (15%) were from most to least accurate in that order. This trend was 
consistent regardless of the sites and size class being considered. Our next step of analysis is 
aimed at investigating how the angle of inclination affects the accuracy of tree height. 
 
Keywords: Height; Accuracy; Mangrove; UAV; Hypsometer 
  


The forester, the form and the geometer: An accuracy analysis of mangrove tree heights measured using forestry techniques, UAVs and hypsometers

http://www.vliz.be/imisdocs/publications/325022.pdf

The forester, the form and the geometer: An accuracy analysis of mangrove tree heights measured using forestry techniques, UAVs and hypsometers

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