Cach-Pérez et al. 2012 (Conference Paper) rainfall gradient, Mexico

Epiphytic bromeliad and hosts communities composition along a rainfall gradient in the Yucatán Peninsula

Author(s):—M. Cach-Pérez, J. Torres, N. Chilpa-Galván, M. Tamayo-Chim, R. Orellana, E. Graham & C. Reyes

Publication:— (2012).

Abstract:—Families with a high proportion of epiphytic species, like the family Bromeliaceae, are important ecological components in the neotropics contributing to the high biotic diversity present. This is the first study to compare the epiphytic bromeliad and host species composition and factors driving this distribution (microclimate, mesoclimate, canopy structure, host species identities) in dry environments, along five different vegetation types in a precipitation gradient of the Yucatan Peninsula, Mexico. We established plots in coastal sand dune, mangrove, and seasonally dry deciduous, semi-deciduous and sub-perennial forests to characterize the structure and composition of the epiphytic bromeliads and hosts communities, and measured the microclimate (light and VPD) in which bromeliads were growing. Within each plot, all possible hosts were counted, identified and tagged, adult bromeliads also were counted and identified; height of the canopy strata, were the epiphytes were found, was also recorded. The diversity of both host and epiphytic bromeliad species was assessed through species richness and the Shannon-Wiever and Simpson indexes; to distinguish the degree of similarity between the studied sites, we used the Sorensen quantitative index. We found a total of 15 species of epiphytic bromeliads and 98 species of phorophytes belonging to 88 genera. Of these genera, 46.2% had epiphytic bromeliads, suggesting a host preference. The number of bromeliads and hosts (both species and individuals) increased from the driest sites to wetter sites. We found low similarity in species composition of both epiphytic bromeliads and host between vegetation types. Although there is a high seasonal microclimatic variation in sites where most of the epiphytes occurred within the five vegetation types, the horizontal distribution of epiphytic bromeliads seemed to respond to the rainfall gradient and the increase in available niches due to increased canopy height.