Modelos para estimar biomasa de Euphorbia antisyphilitica Zucc. en seis municipios de Coahuila

The scarce knowledge about the growth and development of the species of arid and semiarid zones in Mexico, has generated an overuse. Among the most important economically in Coahuila is the candelilla, of which the technical information available for decision-making in management is limited. Therefore, the objectives were: a) to group six municipalities based on the individual production of biomass evaluated in 10 natural populations of Euphorbia antisyphilitica Zucc. and, b) adjust allometric models to estimate the biomass of E. antisyphilitica in different growing conditions in the center and south of Coahuila. With an analysis of variance and the minimum significant difference, the municipalities were grouped; for each group, models were adjusted, using the ordinary least squares method. Three biomass production groups were obtained per individual (GI, GII and GIII). The models to estimate the total green biomass (kilogram per individual) for each group, resulted with an R-Ajus(2) higher than 0.86, in the first two groups, and for GIII it was 0.64, the RMSE (root mean square error) was lower than 0.425 and the parameters of the models were significant (p < 0.05), in the four cases. In addition, the four selected models presented normality, homogeneity of variances and the nonexistence of collinearity between variables. The selected models are statistically reliable to estimate the biomass by individuals of each group considered in this study, so they can be a useful tool in the development of management plans for the use of candelilla.