Reproductive traits and floral visitors of Aechmea distichantha plants growing in different habitats of a South American xerophytic forest

Abstract

Aechmea distichantha, a widely-distributed facultative epiphytic bromeliad species, is present from rainforests to xerophytic forests. At its southernmost distribution (Humid Chaco) it grows in the understory and forest edges. This animal-pollinated bromeliad shows high phenotypic plasticity on its vegetative traits, but there is no information about plasticity on its reproductive traits. Infructescences from shade plants were heavier, had longer rachis, more spikelets, higher number of fruits/spikelet and higher number of seeds/fruit than those from sun plants, but they presented similar number of open flowers. The number of visitation events was similar in both habitats, but more flowers were visited in the sun than in the shade. Flowers were visited by seven species (six insects and one hummingbird). In the sun, the carpenter bee was the most frequent visitor and visited almost all flowers, whereas in the shade different species of visitors attained similar proportion of visits and number of visited flowers. Despite visitation events were similar in both habitats, plants growing in the shade set more seeds/fruit than plants growing in the sun. The higher proportion of visits accomplished by carpenter bees compared to hummingbirds is probably a consequence of the climatic conditions in the austral location of these populations.

Ramet demography of Aechmea distichantha (Bromeliaceae) in two contrasting years in the understory and open areas of a South American xerophytic forest

“…The higher flowering of ramets in the shade is probably associated with milder conditions in the understory. A similar pattern has been recorded for Aechmea distichantha in another study of these forests (Freire et al 2018). In contrast, A. distichantha ramets growing in open areas showed a higher production of ramets than those growing in the understory.…”

“…Our previous studies showed that Aechmea distichantha plants exposed to different environmental conditions (i.e. understory vs sunny areas) showed marked differences in leaf anatomy, plant architecture, biomass allocation, and reproductive traits (Cavallero et al 2009(Cavallero et al , 2011Freire et al 2018). Despite these differences between habitats, the present study showed that the dynamic of A. distichantha populations was more affected by the environmental conditions of a particular year than by habitat conditions.…”

“…Like other tank bromeliads, it has absorptive foliar trichomes that have the capacity to take up water and nutrients from the tank (Leroy et al 2016). It reproduces both sexually and asexually (Mercier & Guerreiro Filho 1990;Bernardello et al 1991;Bianchi et al 2000;Scrok & Varassin 2011;Freire et al 2018). Ramets show high phenotypic plasticity; shade plants have longer leaves and thus are taller and have larger diameters, whereas sun plants have more leaves and larger sheath mass fraction and thus higher maximum tank water contents (Cavallero et al 2009(Cavallero et al , 2011Montero et al 2010).…”

“…Ramets show high phenotypic plasticity; shade plants have longer leaves and thus are taller and have larger diameters, whereas sun plants have more leaves and larger sheath mass fraction and thus higher maximum tank water contents (Cavallero et al 2009(Cavallero et al , 2011Montero et al 2010). Shade plants have heavier infructescences, longer rachis, more spikelets, a higher number of flowers/spikelet and a higher number of seeds/flower than those from sun plants (Freire et al 2018). A specimen of this species was incorporated into the Juan Pablo Lewis Herbarium of the Universidad Nacional de Rosario (UNR 2303, Lewis 877).…”

“…It may propagate both sexually and asexually, but the latter is the more common way of reproduction in these forests (Cavallero et al 2009). This tank bromeliad shows high phenotypic plasticity, and thus ramets growing in contrasting habitats (e.g., understory and forest edges) showed marked differences in their leaf anatomy, plant architecture, biomass allocation, and reproductive traits (Cavallero et al 2009(Cavallero et al , 2011Freire et al 2018). Because of this high phenotypic plasticity and differences in habitat conditions (e.g., light, temperature, rainfall), understory plants had smaller water tanks but probably received higher litterfall than plants located in forest edges or open areas (Cavallero et al 2009;Montero et al 2010).…”