A stand density diagram for Pinus patula Schiede ex Schltdl. & Cham.in Puebla, Mexico

Abstract

A stand density diagram (DMD) is a technical tool for applying quantitative silviculture that contributes to improve the technical management of forests; however, the objective was to generate a density management diagram based on Reineke's stand density index to prescribe thinning for Pinus patula stands in Puebla, Mexico. Data from 252 inventory plots in maximum density that covered all growth conditions and the entire age range were processed. Density and quadratic diameter were processed by statistical regression adjusting Reineke’s model. Self-thinning boundaries were fitted and compared to the data with ordinary least squares and stochastic frontier function (SFF) techniques, by Semi-Normal Model (SNM), the Normal Truncated Model (NTM) and the Normal-Exponential Model (NEM) approaches. An evaluation of the quality of statistical and graphical adjustment showed that the stochastic frontier regression technique (SFR) in its semi-normal modality was superior, so it was selected to determine the line of self-thinning. Maximum stand density indexes were 1 078 trees per hectare for a quadratic reference mean diameter of 20 cm. The DMD was generated by defining the different growth zones of Langsaeter. The DMD is useful to manage and prescribe the intensity of thinning as an intermediate silvicultural treatment in terms of the number of trees per hectare to be removed and their equivalent in basal area per hectare for even-aged stands.