DISTRIBUTION AND ECOLOGICAL ASPECTS OF THE GENUS QUERCUS (FAGACEAE), IN THE STATE OF COAHUILA, MEXICO.

Juan Antonio Encina Domínguez
José Ángel Villarreal Quintanilla


Departamento de Botánica
Universidad Autónoma Agraria Antonio Narro
25315, Buenavista, Saltillo, Coahuila
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Abstract

The oak flora of the state of Coahuila is composed by 31 taxa, from which 20 species, including three varieties, are white oaks (section Quercus) and 10 species are red oaks (section Lobatae). The oak species more widely distributed are Quercus pringlei, Q. intricata, Q. laceyi, Q. invaginata and Q. gravesii. The endemism concept is applied to indigenous species with distribution limited to the state including areas of bordering states. The endemic species are Quercus carmenensis, Q. coahuilensis, Q. gravesii, Q. hintoniorum, Q. invaginata and Q. saltillensis. The highest diversity is found in the oak forest followed by the pine-oak forest and lastly by the submontane shrubland. In general terms, most of the species are distributed in an altitudinal range of 1,500-2,700 m.

The white oaks grow in mountain slopes, hills of semiarid areas and borders of streams in forest canyons. The red oaks prefer humid areas, frequently at the bottom of canyons and slopes of temperate-subhumid forests.

Most of the species were found in the northwest mountains and the southeastern portions of the state, from which Sierra del Carmen is the mountain with the richest oak flora (16 species). The state of Coahuila has species from the Sierra Madre Oriental in the southeastern and from the U.S.A. and Sierra Madre Occidental in the northwestern portions.

The sites with oaks were analyzed through the similarity coefficient of Jaccard. The mountains from the central part of the state are more related with the northwestern mountains. The Planicie Costera del Golfo showed the lowest levels of similarity, with limited relation with the other groups of mountains. The species distribution of patterns are discussed

Key words: Quercus, distribution, Coahuila, ecological aspects.

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