Different leaf traits provide light-acclimation responses in two neotropical woody species

Leaf plasticity to light can affect species distribution in areas with contrasting light availability. Plants can acclimate to prevailing light conditions according to their optimal growth conditions. Our goal was to assess differences in the morphophysiological plasticity of leaves of two woody species ( Inga vera subsp. affinis and Psychotria carthagenensis ) that occur in a riparian forest (low irradiance) and in the ecotone between the riparian forest and a savanna-like formation (high irradiance) in the Southern Pantanal, Brazil. Both species showed lower specific leaf area and higher concentration of carotenoids per leaf area in the ecotone. Moreover, the maximum quantum yield of photosystem II decreased at midday in the ecotone, suggesting the induction of dynamic photoinhibition. Psychotria carthagenensis showed a sharp decrease in leaf water potential at midday in both sites. The light saturation point and non-photochemical quenching of Inga vera increased in the ecotone. Both species had thicker cuticles and mesophyll in the ecotone, and the palisade to spongy parenchyma ratio of P. carthagenensis increased at the same site. Additionally, in the ecotone, the concentration of proteins per leaf area was higher. The results indicate that these species showed different patterns of leaf plasticity, with I. vera presenting increased photosynthetic capacity and P. carthagenensis showing more plasticity in morphoanatomical traits. Therefore, our results suggest that the high potential of photosynthetic use of light by I. vera may help to explain its broader distribution in sites with higher irradiance.