Maximum size-density relationship for mixed forests of Nuevo San Juan Parangaricutiro, Michoacán, Mexico

Introduction: The maximum size-density relationship (MSDR) describes the dynamics of species-mixed stands, and it is essential in the implementation of silvicultural treatments for density control.Objective: To analyze the influence of species composition on MSDR in mixed temperate forests of Nuevo San Juan Parangaricutiro, Michoacán, Mexico.Materials and methods: MSDR was analyzed with a potential and an exponential model under two approaches with observations of mixed species stands. The first (E1) described the MSDR trajectory without taking into account the proportion of species and the second (E2) included the proportion of species in four groups: Pinus, Quercus, other conifers and broadleaves. Both approaches were analyzed with stochastic frontier regression (SFR) and quantile regression (QR).Results and discussion: E1 results were favorable with the use of RC, as it showed a higher trajectory of the data to define MSDR in a linear and concave manner. In E2, the allometric coefficients of the size-density relationship for the four species groups were different and RC estimated the MSDR with species proportion adequately. In shade tolerant species (other conifers and broadleaves), the estimated slope was more negative compared to intolerant species (Pinus and Quercus).Conclusions: For mixed forests, MSDR is adequately explained when it is dependent on species composition, because it influences the behavior of the maximum density line, useful for planning density management strategies in mixed forests.