Plasticity of xylem vessel traits in Ocotea indecora (Lauraceae) wood along an altitudinal gradient in dense montane Atlantic Forest

Abstract We investigated the plasticity of vessel features in Ocotea indecora wood along a 300 m altitude gradient in dense montane rainforest. Our results showed that wood of trees at 1,000 m presented higher potential hydraulic conductivity (kp), which is consistent with wood that invests more in efficient water transport. These results stand in contrast to those from wood of trees at 1,200 and 1,300 m, which presented vessel indices consistent with wood that invests more in the safety of water transport. Comparison between trees with higher kp at 1,000 m and trees with lower kp at 1,200 m showed that vessel-grouping index, vulnerability index, and mesomorphy index were all lower at 1,000 m, while vessel multiple fraction was higher at 1,000 m. At elevations from 1,000 to 1,300 m, we can infer two different relief compartments, plateau and escarpment, both have steep slopes with shallow soils, but on the plateau, they tend to be deeper. Considering the evidence of vessel features, vessel indices and hydraulic conductivity, together with soil traits, climate and landscape relief, we concluded that the difference in investment of water transport vs. safety between trees at 1,000 m vs. 1,200-1,300 m represents vessel plasticity consistent with adaptations that allow the growth, development and reproduction of this species in these different environments.