Tree Diametric Relationships and Their Implications for Estimation of Above-ground Biomass in a Tropical Rainforest

ABSTRACT

The use of diameter at breast height (DBH) measurement in allometric equations for estimation of biomass (AGB) requires that measurements be taken precisely at 130cm from the ground level. However, obtaining this measurement is not always possible. This study aimed to i) investigate the relationship between the DBH and diameters measured at different heights below 130 cm on tree stems, ii) develop an equation for converting diameters measured below 130cm to DBH, and iii) evaluate the accuracy of using converted DBH values to estimate the AGB. We measured the diameters of 376 trees at various stem heights at intervals of 25 cm up to the DBH, in a protected area of the Atlantic Forest, Brazil. Three theoretical models were applied and tested, and the best equation was selected. The relationships between DBH and diameters at 50, 75, and 100 cm did not differ, which allowed the use of one general equation for converting these diameters to DBH. Measurements taken below 50 cm may lead to biased estimations; thus, we propose two additional equations for estimating DBH from these heights. The DBH converted from diameters measured at other heights can be accurately used to estimate the tree AGB and carbon stocks.

Keywords:

• Allometric equations
• stock
• Atlantic forest
• DBH

Acknowledgments

We thank the Dois Irmãos State Park (PEDI) for permission to access and research trees on their grounds and the PPBio Mata Atlântica Program (PPBio-MA) for allowing us the use of the data from the PPBio-PEDI Module. We thank the Federal Rural University of Pernambuco (UFRPE), the Plant Ecology Laboratory (LEVE), and the Post-Graduate Program in Forest Sciences for their assistance and logistical support, the Fundação Grupo Boticário for funding (to A.C.B.L.S, Grant No 1120_20181, Project “Irmãos do Parque”), the CAPES Foundation for granting postgraduate scholarships in Forest Sciences at UFRPE (to N.C.F., J.S.A.C., J.A.S.C., J.N.B.S., and L.S.R.), Tutorial Education Program of the Ministry of Education (PET/MEC) for the scholarship given to A.C.B.L.S., and M.A. Chagas for field assistance. The authors have no conflicts of interest to declare.

Additional information

Funding

This work was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior [-]; Fundação Grupo Boticário de Proteção à Natureza [1120_20181]; Ministério da Educação [-].