Population dynamics of the cactus Mammillaria gaumeri: an integral projection model approach

Abstract

The Cactaceae family in Mexico is particularly important because members of this family exhibit a high degree of endemism. Unfortunately, many species of the Cactaceae are threatened or endangered. We employed an integral projection model for studies of the population dynamics of Mammillaria gaumeri, an endemic cactus of the Yucatán characterized by a small population size. The integral projection model provides estimates of the asymptotic growth rate, stable size distribution, reproductive values, and sensitivities and elasticities of the growth rate to changes in vital rates. Nine locations of this species were studied along the Yucatan coast over a 9-year period. Individuals were classified by plant volume. Most population growth rate (k) values were below unity. The highest elasticity values corresponded to the survival of intermediate size individuals. The percentage of germination in the field was low, and consequently, fecundity values were also low. Reproductive values were observed to increase with plant volume. The stable size distribution of M. gaumeri was skewed toward small individuals. For all years, the kernel showed that individual survival determined the population growth rate.

Survival dynamics of Melocactus conoideus Buining & Brederoo (Cactaceae), a threatened species endemic to northeastern Brazil

“…In addition, if we consider only the adult (G4 stage) individuals of M. conoideus, the rate of survival was high, which is in agreement with the patterns reported for other species in the family (Godínez-Álvarez et al 2003;Godínez-Álvarez & Valiente-Banuet 2004;Hughes et al 2011;Ferrer-Cervantes et al 2012). The decline of survival of Melocactus conoideus along of the months revealed a seasonal influence.…”

“…For Melocactus conoideus populations, the chances of survival were found to be similar for all age classes Mandujano et al 2007;Hughes et al 2011;Ferrer-Cervantes et al 2012). In addition, if we consider only the adult (G4 stage) individuals of M. conoideus, the rate of survival was high, which is in agreement with the patterns reported for other species in the family (Godínez-Álvarez et al 2003;Godínez-Álvarez & Valiente-Banuet 2004;Hughes et al 2011;Ferrer-Cervantes et al 2012).…”

Variation across river channels in demographic dynamics of a riparian herb with threatened status: management and conservation implications

“…Benth. ex Rolfe (Raventós et al., , ), and the threatened cactus species Mammillaria gaumeri (Britton & Rose) Orcutt (Ferrer‐Cervantes et al., ). All these species and our target species were similar in terms of elasticity analyses, where the survival and growth of larger plants contributed most to the changes in the population growth rate.…”

“…MacDoug. & Miranda (Mendez et al., ) and M. gaumeri (Ferrer‐Cervantes et al., ), and for the orchid L. rupestris (Tremblay and McCarthy, ). Therefore, the observed and expected size distribution might differ because habitat stability is unlikely (Bierzychudek, ).…”

“…Continuous monitoring can also help us to identify how much λ departs from unity. For example, over 9 years, M. gaumeri had a λ greater than one in the second and last year of monitoring (Ferrer‐Cervantes et al., ); thus, the study period used here for G. pauciflora might not be sufficient to sample the range of environmental variability experienced by the population (Bierzychudek, ). Evolutionary–ecological studies of Gesneriaceae suggests that the evolution of breeding systems may respond to variation in uncertain habitat conditions (Martén‐Rodríguez et al., ).…”