Abstract

GUZMAN-SANTIAGO, Juan Carlos et al. A generalized nonlinear total height-normal diameter relationship for Pinus greggii and Pinus pseudostrobus in Oaxaca, México. Madera bosques [online]. 2024, vol.30, n.1, e3012552.  Epub Oct 25, 2024. ISSN 2448-7597.  https://doi.org/10.21829/myb.2024.3012552.

Total tree height is an important variable in forestry and forest management, but field measurement is so difficult and costly that, sometimes, mistakes are made that alter its dimension and recording. The objective of the study was to find the best generalized nonlinear equation to describe the height- diameter for Pinus greggii and Pinus pseudostrobus plantations in the Mixteca Oaxaqueña. A sample of 1180 trees was used, measuring normal diameter (dn) and height (At), and stand variables were also determined. Six equations were evaluated, adjusted without the 1.30 m intercept corresponding to dn; the best equation was selected by quantitative and graphical analysis. Omule and MacDonald equation (1) was found to be slightly better in estimates and graphical analyses for describing tree height behavior, meeting the assumptions of normality, homogeneity of variance and residuals independence. The selected equation explained more than 90% of the total variability in height, with root mean squared error ranging from 0.470 m to 0.600 m and biases from -0.051 m to 0.022 m for both species. This is the first equation of its kind to be developed for species in the area, so its application will be useful in forest inventories.

Keywords : generalized equations; statistical indicators; forest inventories; plantations; stand variables.

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