Introduction

Taper equations are useful tools in forest management, and their application can be extended to species in arid or semi-arid ecosystems.

Objective

To develop a compatible system of equations for estimating the volume of individual trees of Juniperus coahuilensis (Martínez) Gaussen ex R. P. Adams in the semi-desert region of Durango.

Materials and methods

A total of 153 trees were destructively sampled. Iterated seemingly unrelated regression (ITSUR) was used to simultaneously fit the system, ensuring minimum error and compatibility among the equations. Heteroscedasticity and autocorrelation in the hierarchical data was corrected using weighted regression and a continuous second-order autoregressive model, respectively.

Results

The system of equations is the first developed for J. coahuilensis in Mexico and includes a taper function, a merchantable volume equation, and equations for stem volume, coarse branch volume, and total volume. The equations explained 98 % of the observed variability in merchantable volume, 86 % in stem volume, and more than 45 % of the variability in branch volume.

Conclusions

The use of the compatible system of equations developed will be useful for the management of J. coahuilensis in arid and semi-arid ecosystems and will reduce errors in total tree volume estimates.

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