Liana species composition differs, in spite of trait similarities, in two adjacent forest types in Central Brazil

Abstract

Abstract:In the Parana basin, the Serra de Maracaju juxtaposes the Seasonal Dry Forest and the cerradão (a phytophysiognomy of Cerrado), two distinct vegetation types that differ in canopy height, tree density, and composition of the understory. In the same way, these differences may be reflected in the composition of climbing plant species found in these two forest types. Thus, in this study we compared the climbing species in two forest fragments of Serra de Maracaju to understand: (1) Are species richness and floristic composition of climbing plants similar in cerradão and seasonal deciduous forest?, (2) What degree of floristic compositional difference exists between the two vegetation types?, (3) Do the two vegetation types differ significantly in climbing mechanisms, life forms, and dispersal syndromes represented among climbing species? For this, we established and sampled four plots per forest type over 24 months. Species were identified and each one classified, based on three discrete traits. Proportional differences were analyzed using chi-square tests. Our results showed that species richness and floristic composition of climbing plants in the cerradão and the seasonal deciduous forest were not similar. Climber species richness in cerradão was 37 while in the seasonal deciduous forest it was 31; they share only 13 species. Four families, Dioscoreaceae, Fabaceae, Malpighiaceae, and Sapindaceae, included over 60 % of the climbing species. The morphological traits most common in both forest types were herbaceous life form, apical twining mechanism, and wind dispersal. Dioscoreaceae was found to be the dominant family, but is the first time to be reported for this condition in Brazil. Bignoniaceae and Passifloraceae ocurred only in the cerradão, and Asteraceae and Combretaceae in the seasonal deciduous forest; some species were found exclusively in a type of forest. Floristic composition of the cerradão and seasonal deciduous forest fragments were substantially different, in spite of physical proximity. However, their climbing species are not statistically distinct in morphological characteristics, possibly due to uniform climatic conditions and the similarity of species because of a shared ancestry (similar families). Rev. Biol. Trop. 65 (3): 1215-1225. Epub 2017 September 01.Key words: climbing mechanism, dispersion, life form, cerradão, Dioscoreaceae.Tropical climates support climbing floras with high species richness, morphological diversity, and phylogenetic diversity. Climber species play essential roles in tropical plant communities, contributing with significant richness to tropical forests (Hergarty & Caballé, 1991;Engel, Fonseca, & Oliveira, 1998), and occurring in both evergreen and seasonal forests. Collectively, climbers show tolerance to large ranges of latitude, altitude, climate, and soil types (Gentry, 1991). At least 133 plant families include the climbing habit, which evolved independently several times; indeed almost 40 % of vascular plant families in Brazil include climbers (Schenck, ...