Resumo

QUINONEZ-BARRAZA, Gerónimo; DE LOS SANTOS-POSADAS, Héctor M.; ALVAREZ-GONZALEZ, Juan G.  e  VELAZQUEZ-MARTINEZ, Alejandro. Compatible taper and merchantable volume system for major pine species in Durango, Mexico. Agrociencia [online]. 2014, vol.48, n.5, pp.553-567. ISSN 2521-9766.

The estimate of the merchantable and total volume is an essential tool in the forest planning and management, so the aim of this study was to evaluate three segmented systems of taper and merchantable volume with bark fitted as simultaneous equations for data from commercial forest species of Durango, Mexico. Fittings were made from three perspectives: 1) for each species in the three systems, 2) global fittings combining all species (reduced model) and 3) overall fit considering dummy variables (full model). Fitness of compatible systems of taper and merchantable volume suggest that studied species present two inflection points; the dendrometric shape from neiloide to paraboloidal, on average for the species studied, happens at 5 % of the total height, whereas the change from paraboloid to cone occurs at 73 %. System 3 (S3) has better qualities of fit between the analyzed systems and the full model with indicator variables with additive effects on Pinus durangensis Martinez was better than the reduced model. With the full model, Pinus ayacahuite Ehrenb presents the less cylindrical stem; Pinus arizonica Engelmannii presents the more cylindrical boles, whereas P. durangensis Martinez, Pinus leiophylla Schlecht et Cham and Pinus teocote Schlecht et Cham have a similar paraboloidal shape. The full model makes efficient the fit of the compatible system, all data in the fit process are used and standard errors of the parameters are reduced.

Palavras-chave : Pinus arizonica; Pinus ayacahuite; Pinus durangensis; Pinus leiophylla; Pinus teocote; compatible system.

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