Resumo

ARIAS-MEDELLIN, Luís Antonio; FLORES-PALACIOS, Alejandro  e  MARTINEZ-GARZA, Cristina. Cacti community structure in a tropical Mexican dry forest under chronic disturbance. Bot. sci [online]. 2014, vol.92, n.3, pp.405-415. ISSN 2007-4476.

When agricultural lands in formerly dry forest are abandoned, chronic disturbance by livestock grazing and wood extraction may set back successional processes precluding older dry forest structure from be reached. We compare cacti density, richness, diversity and evenness in twelve 50 × 50 m plots: six plots in secondary dry forest and six plots in older conserved dry forest at Sierra de Huautla, Central Mexico. Cacti were identified, the life-form of each species was recorded and size was measured to assign individuals into four life-stage classes. Nine cacti species were registered across both forest types. In this dry forest, richness, diversity and evenness of cacti community increased in sites under chronic disturbance, whereas density was not significantly affected. Size structure at community level in the conserved forest showed an increase of individuals with size, whereas in the secondary forest, size structure showed an uneven distribution of individuals, as in populations that regenerate by pulses. In the secondary forest, there was a lower proportion of adults and they were in average, smaller than those in the conserved forest. Chronic disturbance may eventually change cacti community structure, affecting animals that depend on large arboreal cacti for food, perches and/or refuge; therefore, maintenance of biodiversity will be at stake.

Palavras-chave : cattle ranching; Opuntia spp.; Pachycereus grandis; restoration ecology; secondary dry forest; Sierra de Huautla.

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