Oak Distribution Patterns and Water Relations in the Sierra de Santa Rosa, Guanajuato

Alejandro López Mendoza, Alejandra Villaseñor Villanueva, Rafael Aguilar Romero, and Fernando Pineda García.

Published May 2026 in International Oaks No. 37: 89–96

Abstract

In Mexico it is common to find several oak species coexisting in the same region. This is the case in the Sierra de Santa Rosa in Guanajuato, where 13 species of oaks coexist in a semi-arid region with a seasonal precipitation pattern. To assess whether slope-aspect and its associated environmental conditions promote differences in the distribution of oak species, we randomly selected plots in north- and south-facing slopes and registered all oak trees and environmental variables. In addition, we explored if the species differ in their mechanisms to cope with drought and if the trade-off between tolerance and avoidance guides the differentiation. Finally, we investigated the relationship between the strategy of resistance and the hydric habitat of the species. Studying 10 of the 13 species, our findings revealed that south-facing slopes received higher solar radiation and had higher soil temperatures, and that the oak species differed in their distribution between north- and south-facing slopes. We found strong differentiation of the plant water relations traits between the 10 oak species as well as evidence of the tolerance-avoidance to dehydration trade-off. Tolerant species had higher resistance to xylem embolism and lost their total leaf area at the end of the dry season (late-deciduous). On the other hand, avoidant species had stringent stomatal control. Finally, the late-deciduous species were found in drier environments while the evergreen species were found in moister sites. These findings suggest that the high differentiation in water use between species and their distribution in different environments allows the coexistence of closely related species

Keywords

oak species coexistence, environmental gradients, drought resistance strategies, functional traits, slope orientation, phenology

References

CONAGUA, Comisión Nacional del Agua. 2026. Red de estaciones climatológicas. Ciudad de México, México: Servicio Meteorológico Nacional. (https://smn.conagua.gob.mx/es/climatologia/informacion-climatologica/informacion-estadistica-climatologica)

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Martínez-Cruz, J., O. Téllez Valdés, and G. Ibarra-Manríquez. 2009. Estructura de los encinares de la Sierra de Santa Rosa, Guanajuato, Mexico. Revista Mexicana de Biodiversidad 80:145-146.

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