Demographic structure of clonal, endemic, and endangered rheophyte bromeliad Dyckia ibiramensis: asexual vs sexual reproduction

Abstract

In southern Brazil some species of Dyckia genus occur as rheophytes. Dyckia ibiramensis is an endemic bromeliad that occurs in discrete patches of the rocky banks along Itajaí do Norte River, Santa Catarina state. Four populations along Itajaí do Norte River were studied. In each population, all rosettes were counted and the diameter of each rosette was measured. The spatial distribution of the rosettes was identified as an isolated rosette or a clump. The clumps were classified according to the number of rosettes. The total number of rosettes per population ranged from 295 to 1,412. Most rosettes occur in clumps (98.1%), and 41% have reproductive rosettes. The number of rosettes per clump ranged from two to 43 rosettes. The percentage of reproductive rosettes per population ranged from 7.8 to 26.7%. The correlation between the number of clumps or between the total number of rosettes and the area of occupation was significant and positive. Few seedlings and isolated rosettes, production of offshoots occurred on both immature, and reproductive rosettes, and clumps with few rosettes can indicate the clonal propagation predominate in D. ibiramensis. Therefore, the maintenance and monitoring of the populations are essential for its long-term in situ conservation.

Demographic structure across all known populations of the rheophyte Dyckia brevifolia Baker (Bromeliaceae) in the Itajaí-Açu River, Southern Brazil

“…In D. brevifolia, the larger the diameter of the rosettes, the greater the probability of becoming reproductive. In other studies, with bromeliad species, the number of reproductive individuals also increased with the increment of plant size (Benzing, 1981;Hietz et al, 2002;Mondragón et al, 2004;Duarte et al, 2007;Filippon et al, 2012;Rogalski et al, 2021).…”

“…Throughout its distribution, 12 sites (Ressacada, Subida/ Apiúna I, Subida/Apiúna II and Subida/Apiúna III, in the municipality of Apiúna; Subida/Ibirama I, Subida/Ibirama II and Morro Santa Cruz in the municipality of Ibirama; Ascurra in the municipality of Ascurra; Encano Baixo and Encano in the municipality of Indaial; Salto Waissbach I and Salto Waissbach II in the Blumenau municipality) with occurrence of D. brevifolia were recorded and studied (Figure 1), according Rogalski et al (2021).…”

“…In addition, these populations presented the lowest percentages of reproductive rosettes, which could indicate recent (re)colonization. None seedling was registered for the congenere rheophyte D. ibiramensis in four populations studied during one year (Rogalski et al, 2021). Studies with bromeliads indicate that individuals produced sexually are more vulnerable (Cogliatti-Carvalho and Rocha, 2001;Villegas, 2001;Mondragón et al, 2004), that the mortality is higher in the initial stages of development and that seedling survival increases with increasing plant size (Augspurger, 1985;Benzing, 2000;Mondragón et al, 2004;Winkler et al, 2005).…”

“…Regarding the demographic structure, the diameter of the rosettes provides an idea of the age of each individual. However, individuals from clonal propagation have faster growth and require less time to become reproductive (Benzing and Davidson, 1979;Ticktin et al, 2003;Mondragón et al, 2004;Rogalski et al, 2021). Seeds of D. brevifolia, collected in the study area, after germination in a greenhouse took about seven years to reach reproduction (J. M. Rogalski, personal observation).…”

Demographic structure across all known populations of the rheophyte Dyckia brevifolia Baker (Bromeliaceae) in the Itajaí-Açú River, Southern Brazil

“…Throughout its distribution, 12 sites (Ressacada, Subida/Apiúna I, Subida/Apiúna II and Subida/Apiúna III, in the municipality of Apiúna; Subida/Ibirama I, Subida/Ibirama II and Morro Santa Cruz in the municipality of Ibirama; Ascurra in the municipality of Ascurra; Encano Baixo and Encano in the municipality of Indaial; Salto Waissbach I and Salto Waissbach II in the Blumenau municipality) with occurrence of D. brevifolia were recorded and studied (Fig 1 ), according Rogalski et al (2021). The area of occupation of the species in each location was determined from the extreme limits of its occurrence.…”