Aim: Predictions of plant traits over space and time are increasingly used to improve our understanding of plant community responses to global environmental change. A necessary step forward is to assess the reliability of global trait predictions. In this study, we predict community mean plant traits at the global scale and present a systematic evaluation of their reliability in terms of the accuracy of the models, ecological realism and various sources of uncertainty.Location: Global.Time period: Present.Major taxa studied: Vascular plants.Methods: We predicted global distributions of community mean specific leaf area, leaf nitrogen concentration, plant height and wood density with an ensemble modelling approach based on georeferenced, locally measured trait data representative of the plant community. We assessed the predictive performance of the models, the plausibility of predicted trait combinations, the influence of data quality, and the uncertainty across geographical space attributed to spatial extrapolation and diverging model predictions.Results: Ensemble predictions of community mean plant height, specific leaf area and wood density resulted in ecologically plausible trait–environment relationships and trait–trait combinations. Leaf nitrogen concentration, however, could not be predicted reliably. The ensemble approach was better at predicting community trait means than any of the individual modelling techniques, which varied greatly in predictive performance and led to divergent predictions, mostly in African deserts and the Arctic, where predictions were also extrapolated. High data quality (i.e., including intraspecific variability and a representative species sample) increased model performance by 28%.Main conclusions: Plant community traits can be predicted reliably at the global scale when using an ensemble approach and high‐quality data for traits that mostly respond to large‐scale environmental factors. We recommend applying ensemble forecasting to account for model uncertainty, using representative trait data, and more routinely assessing the reliability of trait predictions.

The leaf size-stem size spectrum is one of the main dimensions of plant ecological strategies. Yet the anatomical, mechanical, and hydraulic implications of small versus large shoots are still poorly understood. We investigated 42 tropical rainforest tree species in French Guiana, with a wide range of leaf areas at the shoot level. We quantified the scaling of hydraulic and mechanical constraints with shoot size, estimated as the water potential difference (ΔΨ) and the bending angle (ΔΦ), respectively. We investigated how anatomical tissue area, flexural stiffness and xylem vascular architecture affect such scaling by deviating (or not) from theoretical isometry with shoot size variation. Vessel diameter and conductive path length were found to be allometrically related to shoot size, thereby explaining the independence between ΔΨ and shoot size. Leaf mass per area, stem length, and the modulus of elasticity were allometrically related to shoot size, explaining the independence between ΔΦ and shoot size. Our study also shows that the maintenance of both water supply and mechanical stability across the shoot size range are not in conflict.

El conocimiento de los patrones y trayectorias sucesionales en los bosques secos tropicales es un aspecto fundamental para orientar procesos de restauración en este importante y amenazado ecosistema. En 171 levantamientos en pastizales, arbustales y bosques de un mosaico seco tropical interandino del alto valle del Magdalena (Huila, Colombia) se identificaron y describieron los patrones de sucesión secundaria mediante análisis de conglomerados y escalamiento multidimensional no-métrico a partir de la similitud florística, y la evaluación de cambios florísticos y estructurales con la edad de abandono. Se definieron siete grupos florísticos los cuales revelan claras divisiones en los análisis multivariados. El número total de individuos, la riqueza y el área basal aumentaron con la edad de abandono. Se identificaron grupos florísticos exclusivos para cada categoría de edad de abandono, así como también grupos florísticos compartidos a lo largo de la sucesión. Se identificaron cuatro trayectorias sucesionales: dos en la zona con menor precipitación, las cuales van desde pastizales hasta arbustales y bosques con bajos valores de riqueza florística y baja complejidad estructural, y otras dos en sectores con mayor precipitación, que van desde pastizales limpios y arbolados hasta arbustales y bosques con mayor complejidad estructural y riqueza. Las trayectorias y grupos florísticos definidos pueden considerarse como base para el establecimiento de modelos flexibles de referencia para el diseño, monitoreo y evaluación de los procesos de restauración ecológica que se adelantan en la zona de estudio o en regiones con características ambientales y regímenes de disturbio similares.

One foundational assumption of trait-based ecology is that traits can predict species demography. However, the links between traits and demographic rates are, in general, not as strong as expected. These weak associations may be due to the use of traits that are distantly related to performance, and/or the lack of consideration of size-related variations in both traits and demographic rates. Here, we examined how wood traits were related to demographic rates in 19 tree species from a lowland forest in eastern Amazonia. We measured 11 wood traits (i.e. structural, anatomical and chemical traits) in sapling, juvenile and adult wood; and related them to growth and mortality rates (MR) at different ontogenetic stages. The links between wood traits and demographic rates changed during tree development. At the sapling stage, relative growth rates (RGR) were negatively related to wood specific gravity (WSG) and total parenchyma fractions, while MR decreased with radial parenchyma fractions, but increased with vessel lumen area (V_A). Juvenile RGR were unrelated to wood traits, whereas juvenile MR were negatively related to WSG and axial parenchyma fractions. At the adult stage, RGR scaled with V_A and wood potassium concentrations. Adult MR were not predicted by any trait. Overall, the strength of the trait-demography associations decreased at later ontogenetic stages. Our results indicate that the associations between traits and demographic rates can change as trees age. Also, wood chemical or anatomical traits may be better predictors of growth and MR than WSG. Our findings are important to expand our knowledge on tree life-history variations and community dynamics in tropical forests, by broadening our understanding on the links between wood traits and demography during tree development.