Volume equations for Khaya ivorensis A. Chev. plantations in Brazil

Abstract

African mahogany (Khaya spp.) plantations are in expansion in Brazil and in the world. This fact justifies the need for studies related to its growth and yield. This paper aimed to evaluate the performance of single-entry and double-entry models for estimating merchantable and total volume for Khaya ivorensis plantations before the first thinning (7 years) and expected final cut (15 years). Volume data was from 100 and 46 trees in Minas Gerais and Pará states, respectively, by using an electronic dendrometer (Criterion RD 1000). Observed volumes were calculated by Smalian's formula. To validate the optical dendrometer, 10 trees were felled and had their volume measured, and compared with the volumes measured indirectly. The results showed that observed and estimated volumes were statistically equal, and that double-entry models were more precise than single-entry models. Schumacher and Hall model was the best equation to estimate merchantable volume for first thinning and for final cut in Minas Gerais stands. Spurr logarithmized model was the best equation to estimate total volume for first thinning and Spurr model for final cut in Pará stands. All chosen equations can be used to quantify merchantable and total volumes of Khaya ivorensis grown under similar conditions.

Spatial characteristics and economic value of threatened species (Khaya ivorensis)

“…The median estimated volume was 0.39 m 3 with mean ± SD of 0.76 ± 1.00 m 3 . Due to comparable soil types, that is, Humic Gleysol and ferric Luvisols, and similar humid equatorial climatic conditions for K. ivorensis growth, another specific function selected for this study was based on the prediction model developed in Minas Gerais state, Brazil 24 . Two classes were separated for this study estimation: first thinning (Dbh <30 cm) and final cut (Dbh ≥ 30 cm).…”

“…Volume functions can be categorised into three classes: first, using Dbh as a sole predictor (local volume functions); second, having Dbh and Ht measurements as predictors (regional volume functions); and third, including Dbh, Ht, and an upper stem diameter as a surrogate for stem form, which is particularly good at the national scale (large-scale volume functions) 41 . Oliveira et al 24 suggested that double-entry models (Dbh and Ht predictors) are more accurate than single-entry models (Dbh predictor) when predicting K. ivorensis stand volume. This study adopted two approaches for indirect volume functions: the allometric volume equation (Eq.…”

“…This study adopted two approaches for indirect volume functions: the allometric volume equation (Eq. 3) 42 and the specific K. ivorensis volume equation obtained by Oliveira et al 24 (Eqs. 4 and 5).…”

African Mahogany Plantation Highlights in Brazil

“…We evaluate that most of the research that was published citing K. ivorensis from Brazilian plantations prior to 2019 were related to K. grandifoliola. The following works we are certain that studied K. grandifoliola, and not K. ivorensis as reported: Ribeiro et al (2016;2017;2018a;2018b); Mayrinck et al (2018); Oliveira et al (2018). While we are fairly sure -given the location mentioned on the Materials -of other research papers that report findings of K. grandifoliola and not K. ivorensis (e.g.…”

Vulnerability of African mahogany to cattle predation in a silvipastural system

“…The dendrometric characteristics observed in the present study corroborate those reported by Castro et al (2008) for silvipastural systems in which African mahogany can reach 12 m trunk height, with 22 cm DBH, at seven year of age. In a K. ivorensis pure stand, at seven years of age, the Ht and Hc averages were 17.1 and 7.7 m, respectively and DBH was 25.1 cm, in Piumhi, MG, Brazil (Oliveira et al, 2018).…”