Plant functional groups of species in semiarid ecosystems in Brazil: wood basic density and SLA as an ecological indicator

Deciduousness in arid and semiarid environments is an important adaptive strategy in tree and shrub species to prevent extensive leaf desiccation and nutrient loss during the drought. The loss of leaves benefits some species, since the seasonality of water resources and high temperatures restrict the survival of plants in xeric environments. The aim of this study was to characterize functional groups of caatinga species from soft traits by testing the hypothesis that the four soft trait measured will show a new pattern and thereby characterize plant functional groups, or if the analysis of the chosen traits will converge with deciduousness. The soft traits measured did not form groups based on deciduousness. Three statistically different groups of species could be identified after statistical analysis: (1) low wood basic density; (2) low specific leaf area and high leaf thickness; and (3) high wood basic density. The most important attributes of the first two Principal Component Analysis axis were wood basic density and specific leaf area explaining 40.8 % and 37.4 % of the variation respectively. Albeit no link has been found between SLA and deciduousness, this study represents an additional evidence that perhaps the severity of savanna environments limits leaf longevity, meaning that differences between evergreen and deciduous species are less important.