Introduction:

Plant communities dominated by pinyon pines host abundant species, as they often form ecotones between temperate forests and desert shrublands.

Objectives:

To describe the floristic-structural attributes of pinyon pine forests in San Luis Potosí and to analyze the impact of some environmental factors on the characteristics of these associations.

Materials and methods:

Arboreal plants and shrub flora of nine sites was recorded and analyzed quantitatively using the point-centred quarter method, and qualitatively, using physiognomic profiles and Dansereau diagrams. The groups defined with Jaccard's similarity index were ordered with the environmental factors using a canonical correspondence analysis.

Results and discussion:

The floristic richness was 597 species including Pinus cembroides Zucc., Pinus pinceana Gordon. & Glend., Pinus nelsonii Shaw., Pinus discolor D. K. Bailey & Hawksw. and Pinus johannis Rob.-Pass., which form associations with Juniperus flaccida Schltdl., Yucca spp. and Quercus spp. The floristic similarity depends on several factors including altitude, slope, pH, organic matter and calcium in soil.

Conclusion:

Pinyon pine forests in San Luis Potosí are dominated by five species of Pinus with heterogeneous floristic composition, so each community should be managed according to specific ecological characteristics.