This dataset contains the underlaying data for the study:Tropical forests have long been thought to be in stable state, but recent insights indicate that global change is leading to shifts in forest dynamics and species composition. These shifts may be driven by environmental changes such as increased resource availability, increased drought stress, and/or recovery from past disturbances. The relative importance of these drivers can be inferred from analysing changes in trait values of tree communities. Here, we evaluate a decade of change in species and trait composition across five old-growth Neotropical forests in Bolivia, Brazil, Guyana and Costa Rica that cover large gradients in rainfall and soil fertility. To identify the drivers of compositional change, we used data from 29 permanent sample plots and measurements of 15 leaf, stem and whole-plant traits that are important for plant performance and should respond to global change drivers.We found that forests differ strongly in their community-mean trait values, resulting from differences in soil fertility and annual rainfall seasonality. The abundance of deciduous species with high specific leaf area increases from wet to dry forests. The community-mean wood density is high in the driest forests to protect xylem vessels against drought-cavitation, and is high in nutrient poor forests to increase wood longevity and enhance nutrient residence time in the plant. The species composition changed over time in three of the forests, and the community-mean wood density increased and the specific leaf area decreased in all forests, indicating that these forests are changing towards later successional stages dominated by slow-growing, shade-tolerant species. We did not see changes in other traits that could reflect responses to increased drought stress, such as increased drought-deciduousness or decreased maximum adult size, or that could reflect increased resource availability (CO2, rainfall or nitrogen). Changes in species and trait composition in these forests are, therefore, most likely caused by recovery from past disturbances. These compositional changes may also lead to shifts in ecosystem processes, such as a lower carbon sequestration and “slower” forest dynamics.For 29 permanent sample plots in two census years across five old-growth Neotropical forests in Bolivia, Brazil, Guyana and Costa Rica, the following data are available: values of 15 leaf, stem and whole-plant traits at the community-level, and the plot scores along two principal component axes that represent species composition.

Date Submitted: 2016-03-10