Abstract

HERNANDEZ-RAMOS, Jonathan et al. Forest plantations site index for Pinus patula in Mexico State. Madera bosques [online]. 2022, vol.28, n.2, e2822308.  Epub Apr 14, 2023. ISSN 2448-7597.  https://doi.org/10.21829/myb.2022.2822308.

The lack of quantitative silvicultural tools to classify the productivity of forested areas in the planning, management, and use of commercial forest plantations (CFPs) is a recurring problem. The objective was to model the site index (SI) as a function of age (E) by including covariates for CFPs of Pinus patula in forest regions VI and VII of the State of Mexico. Data from 65 sampling sites (250 m2) distributed in 90.8 ha of eleven PFC between four and 20 years old were used to adjust the growth model of Cieszewski y Bella (1989) with the R® software using fixed and mixed effects. The statistical evaluation was performed by fulfilling the regression assumptions and the values of the mean bias ( $\overline{S}$), bias in percentage ( $\overline{S}$%) and the root mean square error (RMSE). Growth curves for dominant height (Ad), current and mean annual increase (ICA and IMA) were generated. The model complies with the regression assumptions. The differences in Ad are determined by the topographical exposure where the lands facing East and North are the most productive. The $\overline{S}$, $\overline{S}$% and RMSE were -0.091 m, -0.358% and 2.4 m, respectively. Polymorphic growth curves at a base age of 20 years described the Ad and the SI was determined with labels of 19 m, 22 m, and 25 m. The maximum ICA and technical turn were at six and eleven years. Classifying CFPs according to their yield and timber productivity provides guidelines for their silvicultural management.

Keywords : dominant height; polymorphic growth; mixed effects; growth pattern; timber yield.