Background:

Knowledge of the the vegetation structure and the environmental factors related to its distribution is essential to establish management and conservation strategies. In Mexico there are large regions without this type of study, such as the Sanganguey volcano, Nayarit.

Questions:

What plant associations develop in the Sanganguey? Which species have structural importance and what environmental variables are related to their distribution?

Study species:

Structurally important trees and shrubs.

Site and years of study:

Sanganguey plant associations in an annual period.

Methods:

Twenty plots of 2,500 m2 each were established for sampling the tree stratum; and 20 subplots of 25 m2 each, for the shrub stratum in Sanganguey (1,500-2,340 m asl). Basal area, coverage, density and importance value of the species were estimated. In addition, the floristic similarity between associations and the relationship between association-environmental factors was calculated by means of cluster analysis and canonical correspondence.

Results:

In Sanganguey 154 vascular plant species and nine associations were identified: Q. urbanii-Alnus jorullensis, Quercus aristata-Q. glaucoides, Q. calophylla, Q. castanea-Q. convallata, Q. laeta, Q. obtusata-Pinus devoniana, Q. obtusata-Q. rugosa, Q. praeco-Q. castanea, and Q. salicifolia-Q. magnoliifolia. Altitude, slope, predregosity and organic matter were the variables most related to their distribution.

Conclusions:

The composition, structure and distribution of Sanganguey Quercus forests are related to the high environmental heterogeneity along the altitude gradient. Species and plant association’s richness make it an area of interest to state level.