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Ecology |
2Departamento de Biología, Área de Botánica Estructural y Sistemática Vegetal, Universidad Autónoma Metropolitana-Iztapalapa, Av. Michoacán y La Purísima s/n, Col. Vicentina, Iztapalapa, C. P. 09340, México, D.F., México; 3Instituto de Ecología, Universidad Nacional Autónoma de México, Departamento de Ecología Funcional y Aplicada AP. 70-275, Circuito Exterior, Ciudad Universitaria, 04510 Mexico, D.F., México
The vertical structure of fern spore banks was studied in a xerophilous shrubland, montane rain forest, and pineoak forest in Hidalgo, Mexico, using the emergence method. Soil samples were collected in April 1999 at depths of 010, 1020, and 2030 cm. Viable spores decreased significantly with depth in all vegetation types, and the highest number of prothallia and sporophytes was found in the uppermost layer. The montane rain forest and the xerophilous shrubland had the largest and the richest banks, respectively. Twenty-three fern taxa were registered in the aboveground vegetation, 12 in the soil banks, and 43.5% were in both. Aboveground and in the soil bank, the xerophilous shrubland, the montane rain forest, and the pineoak forest had, 17 and 7, 1 and 6, and 7 and 3 taxa, respectively. These were distributed differentially in relation to depth. The Sørensen index indicated a similarity of 61.5% between the xerophilous shrubland and the montane rain forest, and the Czeckanovsky index indicated 19.75%. The presence of viable spores in the soil of all vegetation types confirmed the existence of natural spore banks. Long-distance dispersal was an important factor determining the specific composition of the xerophilous shrubland and the pineoak forest.
Key Words: ferns Mexico soil propagule banks spores vegetation types
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