Plant functional types and trait values in the Paraná River floodplain: modelling their association with environmental features

Abstract

Our aim was to assess whether plant trait values and functional types are associated with environmental features in floodplain wetlands. The study was conducted in the Lower Paraná River floodplain, mostly dominated by marsh communities. In 72 sites, 16 functional traits were screened for 95 plant populations of 44 species. Since the interspecific variability in trait values resulted higher than the intraspecific variability, plant species (and not populations) were hierarchically classified into plant functional types (PFTs). Ten PFTs were identified. Two trade-offs were observed: resource acquisition vs. resource conservation or resource assignment to tissues conferringanoxia or salinity tolerance, and fast growth vs. light interception. Cover-abundance of the PFTs and community-level weighted means (CWMs) of the non-redundant traits were computed for 80 sites. Generalized linear models were used to assess the effect of environmental variables (landscape units,topographic positions, flooding frequency and eight soil variables) on the CWMs and on distributionof PFTs occurring in 15 sites or more. A two-stage modelling process was carried out to account forthe presence?absence and cover?abundance of PFTs separately. The association between CWMs andenvironmental features was relatively weak but significant for six out of the eight traits analysed.Besides, satisfactory models were found for eight out of the nine PFTs assessed. In the studiedfloodplain, PFTs ? interpreted in terms of life strategies ? seem to be a better approach than CWMsto understand and characterise functional responses to the environment.