Density management diagram for the genus Pinus in the Pueblo Nuevo ejido, Durango State

Abstract

A density management diagram (DMD) was developed for the genus Pinus, from a plot of land managed by the ejido Pueblo Nuevo in Durango, whose aim is the production of sawn timber. The data were obtained from the forest inventory, provided by UMAFOR 1008, El Salto, Durango, of 196 sampling sites of which the dasometric variables were estimated: number of trees per hectare N, dominant height H0, mean square diameter dg and volume V. The diagram was developed with two base equations, representing the mean square diameter dg and Volume V. The Hart-Becking IH Spacing Index was calculated in order to be used as a reference in cuts planning, the base equations were adjusted through the non-linear regression of the nls function in the statistical software R project 3.4.0. Rstudio 1.0.143, through an iterative process, the simultaneous adjustment of the equations was performed by the FIML (full information maximum likelihood) method. The equation system was simultaneously adjusted using the MODEL procedure of the SAS/ETS^® statistical system. The goodness of adjustment of the statisticians gave a determination coefficient R²= 0.7074 and a mean square error RMSE = 2.7563 for the equation of dg and R² =  0.9947, RMSE = 7.9114 for the Volume. The Hart Index isolines reached minimum and maximum values as a percentage of the density of 16 out of 56 respectively. A cutting scheme was proposed according to the production objective: wood with dimensions for sawmill.