Abstract
Abstract: The Araucaria Forest is a unique plant formation, practically restricted to the Atlantic Forest biome, in the South and Southeast of Brazil. It is immensely fragmented and its area is reduced to a minimum fraction, from 13 to 2% of the original area, due to intense anthropic exploitation. Our study evaluated the richness and floristic composition of ferns and lycophytes within three Araucaria forest fragments, in Rio Grande do Sul, Brazil. For the floristic inventory, a parcel of 1 ha (100x100m) was demarcated inside three fragments, which were classified by size: large (246 ha - H1LF), medium (57 ha - H2MF) and small (5.2 ha - H3SF). Occurring species life forms and preferential substrates up to 4 meters above ground were recorded. In total, 55 species were catalogued, only two of which were lycophytes, distributed in 32 genera and 17 families. Considering the area of fragments, the recorded species richness has decreased, presenting greater numbers in H1LF (48), followed by H2MF (33), and H3SF (29). In the three sites, terrestrial substrate and the hemicryptophyte species life form predominated. We observed that one hectare of a larger forest fragment presented 65% more species than that of a smaller one, considering that the smaller fragment total area represents only 2% of the larger forest's area. On the other hand, one hectare of the smaller fragment contributed 17% to fern and lycophyte species conservation occurring in Brazilian Araucaria Forests, and 8% to the state of Rio Grande do Sul's total richness. The diverse heterogeneity and species composition grants floristic identity to each of the studied forest interiors. Our results highlight the need to include the botanical parameters here analyzed in management, conservation degree evaluation, and maintenance of Araucaria Forests plant biodiversity.
Highlights
Araucaria Forest (AF) or Mixed Ombrophilous Forest (MOF) is a unique vegetation formation on the planet (Koch 2002), practically restricted to the Atlantic Forest biome in South and Southeast Brazil (Backes, 2009)
Ferns and lycophytes richness demonstrated the importance of studying AF interiors for spore-producing vascular plant biodiversity conservation
Our results corresponded to 40% of the species cited for Araucaria Forests in Rio Grande do Sul, as well as 14.62% of the total species recorded in this state
Summary
Araucaria Forest (AF) or Mixed Ombrophilous Forest (MOF) is a unique vegetation formation on the planet (Koch 2002), practically restricted to the Atlantic Forest biome in South and Southeast Brazil (Backes, 2009). Araucaria angustifolia (Bertol.) Kuntze is an arboreal species that stands out in the upper stratum and confers typical and unique characteristics to the forest structure composition (Kozera et al 2006). Another typical species of MOF is the Dicksonia sellowiana Hook., which is a tree fern found more frequently in areas with high araucaria density (Fernandes 2000). In addition to the fact that they harbor characteristic species and unique biological attributes (Oliveira-Filho et al 2013), Araucaria Forest remaining areas have been considered an environmental conservation priority (Duran & Peixe 2008)
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