This work compares potential xylem hydraulic efficiency among Bignoniaceae lianas, shrubs and trees. Five species from each growth habit were analysed to determine variance among habits based on quantitative and qualitative wood anatomical features. Potential hydraulic conductivity was calculated for each species in order to compare efficiency of water transport. Cambial variants are present in the Bignonieae tribe, as phloem wedges in lianas and phloem arcs in shrubs. Lianas present vessel dimorphism, quantitatively evidenced by the ratio of maximum by minimum vessel diameter of about 20, higher percentage of vessel area and lower percentage of fibres compared with the self-supporting species studied here. Potential hydraulic conductivity is higher in lianas due to the presence of wider vessels and it is hypothesised that the narrow vessels can function as back-up for water conduction when wider vessels are cavitated.

1. In tropical rainforest, most vascular plants have some capacity to resprout, and lianas are often effective resprouters after canopy fall. However, the diversity of resprouting responses of liana species and the consequence for plant persistence are poorly understood. We hypothesized that variation in regeneration among | 1313

Question: Have liana density and biomass increased in central Amazonia over the last 10 years? Can a spatially explicit consideration of liana mortality and recruitment rates across hydro-edaphic and tree turnover gradients at the landscape scale explain changes in liana density and biomass? Location: Ducke Forest Reserve, 26 km north of Manaus, Amazonas, Brazil.Methods: Data were collected on 30-1 ha permanent plots in a central Amazonia undisturbed old-growth rain forest 10 years after the first census. We measured lianas at 1.3 cm above their rooting point, with a diameter (D) ≥ 5 cm and subsampled lianas ≥1 cm diameter in 0.25 ha per plot. We estimated above-ground density and biomass changes, mortality rate, recruitment and diameter increase. Soil cations and available P were reduced to two dimensions with PCA and the first axis used as the descriptor of soil fertility. Height above the nearest drainage, a proxy for water availability, tree turnover (D ≥ 10 cm) and soil fertility were used as predictors of liana dynamics.Results: No significant change in liana density and biomass, averaged over the 30km 2 landscape, was observed over the last 10 years. In 2014, liana density was generally higher in more fertile soils, and it increased in areas closer to the water table and with higher tree turnover in the valleys. This pattern resulted from the higher liana recruitment rates in valley plots closer to the water table. Liana mortality rates were uniform across plots, similar among the diameter classes and, on average, higher than recruitment. Conclusion:We did not find any evidence that liana density and biomass have been increasing in this Neotropical site over the last 10 years. These findings suggest that the current knowledge on liana increase trends in the Neotropics should be reviewed if supported by further tropical studies. K E Y W O R D Sabove-ground biomass, central Amazonia, climbing ecology, liana mortality, liana recruitment, liana turnover, old-growth rain forest, tree turnover, vines 652 |