Species-specific and regional volume models for 12 forest species in Durango, Mexico

Introduction: Estimating the volume of individual trees is an important aspect in dendrometry and in the conducting of forest inventories. Objective: Significant differences were evaluated in additive equation systems for estimating the total volume of individual trees in nine species of the genus Pinus (P. cooperi, P. durangensis, P. arizonica, P. leiophylla, P. teocote, P. engelmannii, P. lumholtzii, P. strobiformisand P. herrerae), and three of the genus Quercus (Q sideroxyla, Q, durifoliaand Q, rugosa), and among regional forest management units (UMAFOR) when dealing with the same species. Materials and methods: To evaluate whether equation systems are different among tree species of the same genus and among the UMAFORs for the same species, two complementary statistical analyzes were used based on the fitting of a reduced and a full equation system: the F test of nonlinear extra sum of squares method, and the parameter significance analysis. Results and discussion: For most of the species studied, equation systems are significantly different. The need to use regional models in 10 of the 12 tree species, except for P. strobiformis and Q, rugosa, is also reported. Conclusion: The use of a state model for P. strobiformis and Q rugosa is recommended.