Relationship between Use Value and Ecological Importance of Floristic Resources of Seasonally Dry Tropical Forest in the Balsas River Basin, México 1 BELINDA MALDONADO 2,3 ,JAVIER CABALLERO * ,2 ,ALFONSO DELGADO-SALINAS 4 , AND RAFAEL LIRA 5 2 Jardín Botánico, Instituto de Biología, Universidad Nacional Autónoma de México, Apartado Postal 70-233, C.P. 04510, México D.F., México 3 Centro de Investigación en Biodiversidad y Conservación, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, , C.P. 62209, Cuernavaca, Morelos, México 4 Departamento de Botánica, Instituto de Biología, Universidad Nacional Autónoma de México, Apartado Postal 70-237, C.P. 04510, México, D.F., México 5 Laboratorio de Recursos Naturales, UBIPRO, F.E.S.-Iztacala, Universidad Nacional Autónoma de México, Av. de los Barrios No. 1, Los Reyes Iztacala, , Tlalnepantla, C.P. 54090, Estado de México, México *Corresponding author; e-mail: jcaballero@ibiologia.unam.mx Relationship between Use Value and Ecological Importance of Floristic Resources of Seasonally Dry Tropical Forest in the Balsas River Basin, México. The use of seasonally dry tropical forest in the Balsas River Basin, Mexico was utilized as a model to study the relationship between the use value and the ecological importance of wild flora in nine study sites that have an indigenous-Mestizo cultural gradient. Ethnobotanical data from the area were used to obtain the use value per species and correlate it with the ecological importance value of the species found in 0.9 ha. We test the hypothesis that the most used species are the most ecologically important and that this relationship is affected by the changing cultural process that occurs in Mexican rural communities. We registered 320 species, 56.25 % of which are useful and fall into twelve use categories. The study sites showed similar percentages of useful plants. We found relationships between the use value of the species and of the main categories (medicinal, construction, fire- wood, and food) with the ecological importance value. The frequency was the ecological attri- bute that determined the use of species in the main categories of use, while the density and dominance attributes were related respectively to the medicinal and food categories. There were differences regarding cultural groups. Indigenous groups mentioned the use of medicinal, edible, and firewood plants more frequently, whereas the Mestizo group pointed out more species used for construction. Relación entre valor de uso e importancia ecológica de los recursos vegetales del bosque estacional seco en la cuenca del Rio Balsas, Mexico. El uso de la bosque tropical caducifolio de la Cuenca del Río Balsas, México, se utilizó como modelo para estudiar la relación entre el valor de uso y la importancia ecológica de la flora silvestre de nueve sitios de estudio que tienen un gradiente cultural indígena-mestizo. Se consideró información etnobotánica del área para estimar el valor de uso de las especies y se relacionó con el valor de importancia ecológica de las especies encontradas en 0.9 ha. Ponemos a prueba la hipótesis de que las especies más utilizadas son las de mayor importancia ecológica y que esta relación se ve 1 Received 18 November 2010; accepted 31 January 2013; published online ___________ . Electronic supplementary material The online version of this article (doi:10.1007/s12231-013-9222-y) contains supplementary material, which is available to authorized users. Economic Botany, XX(X), 2013, pp. 1–13 © 2013, by The New York Botanical Garden Press, Bronx, NY 10458-5126 U.S.A.