Functional macrophyte trait variation as a response to the source of inorganic carbon acquisition

BACKGROUND: This study aims to compare variation in a range of aquatic macrophyte species leaf traits into three carbon acquisition groups: HCO(3)(−), free CO(2) and atmospheric CO(2). METHODS: The leaf functional traits were measured for 30 species from 30 softwater lakes. Macrophyte species were classified into (1) free CO(2), (2) atmospheric CO(2) and (3) bicarbonate HCO(3)(−) groups. In each lake we collected water samples and measured eight environmental variables: depth, Secchi depth, photosynthetically active radiation (PAR), pH of water, conductivity, calcium concentration, total nitrogen and total phosphorus. In this study we applied the RLQ analysis to investigate the relationships between species functional traits (Q) and their relationship with environmental variables (R) constrained by species abundance (L). RESULTS: The results showed that: (1) Aquatic macrophytes exhibited high leaf trait variations as a response to different inorganic carbon acquisition; (2) Traits of leaves refer to the acquisition of carbon for photosynthesis and serve to maximise this process; (3) In the wide softwater habitat, macrophyte species exhibited an extreme range of leaf economic spectrum (leaf area, leaf dry weight and specific leaf area) and wide range of shape trait expressed as circularity; (4) Macrophyte leaf traits are the result of adaptation to carbon acquisition in ambient environment.