Distribution patterns of ferns and lycophytes in the Coastal Region of the state of Rio Grande do Sul, Brazil

Abstract

A survey of ferns and lycophytes of the Coastal Region of the state of Rio Grande do Sul (CRRS) was performed based on fi eld work and collections of the main regional herbaria. Th e following were evaluated for each species: preferential habits (terrestrial, epiphytic or aquatic), geographic distribution patterns and habitats (forest, grassland, and wetland). Th e occurrence of a latitudinal gradient in diversity was tested over fi ve latitudinal ranges using the Sørensen Similarity Index. A total of 17 lycophyte and 206 fern species representing 28 families was found between the latitudes of 29° and 34°S. Exclusively terrestrial species were predominant (162), with the majority (113) exhibiting wide Neotropical distributions, followed by species that also occurred in the state of Paraná (44). Th e forest habitat harbored the greatest number of species (159), while grasslands had the fewest (26). Cluster analysis showed pronounced fl oristic diff erentiation among latitudinal Ranges III (31°01' to 32°S) and IV (32°01' to 31°S), with a similarity index of only 0.41. Our results demonstrate a strong north-to-south reduction in species richness in the study area, which is related to environmental conditions along the latitudinal gradient and, especially, microclimatic diff erences in the transition zone between the Atlantic Forest and Pampa biomes.

Catalogue of the vascular epiphytic flora of Uruguay

“…The lower orchid richness recorded in our study is in accordance with the strong north to south decrease of species and genera in eastern subtropical South America (Waechter 1998), extending from Paraná state (Brazil) to Buenos Aires province (Argentina). The same decreasing tendency was reported for epiphytic cacti (Bauer & Waechter 2011) and ferns (Gonzatti et al 2016;Machado et al 2016), and might also be explained by the decrease in average precipitation and temperature, and the concomitant increase of water deficit and number of frost days south of 30ºS (Barros et al 2006).…”

“…Geographic distribution data refers to the departments where the species were registered based on herbarium specimens and field observations, and is abbreviated as follows: Artigas: AR; Canelones: CA; Cerro Largo: CL; Colonia: CO; Durazno: DU; Flores: FS; Florida: FA; Lavalleja: LA; Maldonado: MA; Montevideo: MO; Pay: PA; Río Negro: RN; Rivera: RI; Rocha: RO; Salto: SA; San José: SJ; Soriano: SO; Tacuarembó: TA, and Treinta y Tres: TT. Additionally, the distribution in neighboring regions of Uruguay was investigated in order to detect the southernmost limit for each species; for this purpose we consulted several online databases (GBIF 2018; SPLink 2018; Flora do Brasil 2020 2019; IBODA 2019), publications concerning vascular epiphytes (Bauer & Waechter 2011;Perleberg et al 2013;Carneiro et al 2016;Gonzatti et al 2016;Machado et al 2016;Martínez et al 2016;Guerrero & Cellini 2017;Pellegrini 2018), and in some cases data from herbarium labels. Habitat distribution follows the forest classification previously described (see Study area).…”

Epiphytic ferns in swamp forest remnants of the coastal plain of southern Brazil: latitudinal effects on the plant community

“…Moreover, epiphyte-phorophyte specificity is common (Cortez 2001;Windisch 2002;Schmitt et al 2005). The concentrated distribution of arborescent ferns in the extreme north of the coastal region, and their gradual reduction to south (Gonzatti et al 2016), along with epiphyte-phorophyte specificity, can explain why the distribution of many epiphytic species is limited to the south of study area. In this context, the epiphyte species are limited, not only by local microclimatic conditions, but also by the lack of specific phorophytes, that become more sparse or absent toward the south, which is also influenced by climatic changes.…”

“…Though many fern species occur in Rio Grande do Sul, through Torres Gateway there is a strong latitudinal gradient of diversity along the north -south regions of the coastal plain of Rio Grande do Sul (see Gonzatti et al 2016) because of climatic differences along this region (Waechter 1998a). In addition, the paleogeographical evolution of the region of the coastal plain also contributed to the latitudinal gradient of fern diversity (Lorscheitter 2003).…”

Abiotic environmental conditions for germination and development of gametophytes of Cyathea phalerata Mart. (Cyatheaceae)

“…The fertile leaves obtained from the natural environment in which C. phalerata occurs were collected during the months under these conditions. The germination result observed at the temperature range tested contributes to explain the restricted occurrence of C. phalerata until the 30º S parallel of Rio Grande do Sul (Gonzatti et al 2016). At further south latitudes, the reduction in precipitation and temperature, as well as the increase in cold days, associated with frost events (Waechter 1990), may be associated with the reduction in the germination capacity in the natural environment.…”