Introduction:

Communities dominated in the canopy by pinyon pines harbor species richness and have complex physiognomy because they form an ecotone between arid and temperate zones.

Objectives:

To describe the floristic attributes that distinguish four communities dominated by pinyon pines; define units based on floristic composition and structure; and determine the influence of edaphic factors.

Materials and methods:

The flora of four communities in the state of Zacatecas was recorded. The arboreal and shrub vegetation was analyzed quantitatively using the point-centered quarter technique. Semi-realistic physiognomic profiles were made for each site. The groups resulting from cluster analysis were ordered with edaphic factors through a canonical correspondence analysis.

Results and discussion:

Floristic richness was 244 species; each community contains between 60 and 80 species. Structurally, three physiognomic variants were recorded: forests dominated by Pinus cembroides Zucc.; association of P. cembroides - P. cembroides var. bicolor Little; and forest dominated by P. maximartinezii Rzed. The pH, electrical conductivity and soil texture have a great influence on the structure and plant composition of the communities. The P. cembroides - P. cembroides var. bicolor association and its accompanying species develop in nutrient-poor soils, while P. maximartinezii forests prefer shallow soils.

Conclusion:

The floristic similarity among communities was low. Each community must be managed differently, meeting the particular requirements of the species that develop there.

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