Résumé
QuestionsHow do resource acquisition-related traits and stress tolerance-related traits shift along Cu and Co gradients? What are the relative contributions of species turnover and intraspecific variation in driving these shifts?
LocationFungurume V hill, Katanga province, Democratic Republic of Congo.
MethodsWe measured five functional traits (vegetative height, leaf area, specific leaf area (SLA) and leaf Cu and leaf Co concentration) related to resource acquisition, competitive ability and metal tolerance strategy for 37 of the most abundant species from 32 plots along natural Cu and Co gradients (from 92 to 6737 mgkg(-1) and 10 to 655mgkg(-1), respectively). Linear regression was applied to analyse species-level and community-level changes in these traits along the study gradients. Using variance decomposition, we evaluated the relative contribution of intraspecific variation and species turnover to the total community variation along the Cu gradient.
Results and ConclusionsAt the community level, plant height and leaf area decreased while SLA and leaf metal concentrations increased with increasing soil metal concentration. At the species level, patterns were often idiosyncratic and lacked generality. As a result, species turnover was the predominant factor explaining community-level variation along the study gradients, which was particularly clear for variation in leaf Cu concentration. This reflects the constitutive ability of some species to exclude metal, while other species can tolerate high metal concentrations in their leaves. The study emphasizes the importance of evaluating the origin of phenotypic variations observed at the community level.