Cacti community structure in a tropical Mexican dry forest under chronic disturbance

Abstract

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 identifi ed, 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 signifi cantly 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. Key words: cattle ranching, Opuntia spp., Pachycereus grandis, restoration ecology, secondary dry forest, Sierra de Huautla.Resumen: Cuando las tierras de cultivo son abandonadas, la ganadería extensiva y la extracción de productos naturales son perturbaciones crónicas que puede afectar el proceso de sucesión natural que llevaría a la selva estacional a su estructura original. Se comparó la densidad, riqueza, diversidad y equitatividad de la comunidad de cactáceas en 12 parcelas de 50 × 50 m: seis parcelas localizadas en la selva secundaria y seis parcelas en la selva conservada en Sierra de Huautla, centro de México. Todas las cactá-ceas fueron identifi cadas, se registró su forma de vida y todos los individuos se clasifi caron en cuatro etapas de su ciclo de vida según el tamaño. Nueve especies de cactáceas fueron registradas en ambos tipos de selva. En esta selva estacional, la riqueza, diversidad y equitatividad de la comunidad de cactos aumentó en los sitios bajo perturbación crónica, mientras que la densidad no se vio afectada. En la selva conservada, la estructura de tamaños de la comunidad mostró un mayor número de individuos de tallas mayores, mientras que en la selva secundaria la estructura de tamaños mostró una distribución no uniforme de individuos, como sucede en poblaciones que muestran pulsos de regeneración. En la selva perturbada se registró una menor proporción de individuos adultos y estos fueron, en promedio, más pequeños que los registrados en la selva conservada. La perturbación crónica puede eventualmente cambiar la estructura de la comunidad de cactáceas con efectos negativos para los animales que dependen de la comida, perchas y ...

Flower biology of the cactus Coryphantha elephantidens in the tropical dry forest of Central Mexico

“…Human activities are a major threat to this species, with apparent local extinction of populations in previously recorded localities in the state of Morelos (Vázquez‐Benítez, 2007). In the tropical dry forest, C. elephantidens can be found in both primary (Arias‐Medellín, Flores‐Palacios, & Martínez‐Garza, 2014) and secondary vegetation (Martínez‐Peralta et al, 2016); however, open areas within the tropical dry forest (e.g. induced pastures) favor higher population density and recruitment (Cazares‐Soriano, 2018).…”

“…Representative woody plants at the site include Amphipterygium adstringens , Cresentia alata , Bursera ariensis , B. copallifera , B. lancifolia , B. linanoe , Acacia cochliacantha , Conzattia multiflora , Lysiloma acapulcensis , Lysiloma divaricatum , Mimosa albida , Mimosa pudica and Ceiba aescuifolia (Cazares‐Soriano, 2018). Besides C. elephantidens , eight other species of Cactaceae are found in Quilamula (Arias‐Medellín et al, 2014). Among these species, Opuntia atropes and O. decumbens were observed at the study sites, but were not flowering when we sampled C. elephantidens .…”

Reproductive ecology of the prickly pear Opuntia atropes, a native plant subject to management

“…Opuntia atropes is appreciated for the quality of its nopalitos (young cladodes used for human consumption) (Reyes-Agüero et al 2005a;López-Gutiérrez et al 2015). It is widely used as fodder and living fences (Maldonado-Almanza 2013; Arias-Medellín et al 2014;Pérez-Sánchez et al 2015). Like many Opuntia species, O. atropes is clonally propagated, mainly when used for living fences (personal observation).…”

“…In the tropical dry forest of Morelos state in central Mexico, O. atropes is used as a food resource by humans, as the young cladodes are highly appreciated (Maldonado-Almanza 2013). In this area, O. atropes is tolerated within agroforestry systems, and nopaleras are frequently found at the intersection of native tropical dry forests and lands that have been transformed for agriculture and livestock uses (Arias-Medellín et al 2014).…”