1. Quantifying the impact of habitat disturbance on ecosystem function is critical for understanding and predicting the future of tropical forests. Many studies have examined post-disturbance changes in animal traits related to mutualistic interactions with plants, but the effect of disturbance on plant traits in diverse forests has received much less attention. 2. Focusing on two study regions in the eastern Brazilian Amazon, we used a trait-based approach to examine how seed dispersal functionality within tropical plant communities changes across a landscape-scale gradient of human modification, including both regenerating secondary forests and primary forests disturbed by burning and selective logging. 3. Surveys of 230 forest plots recorded 26,533 live stems from 846 tree species. Using herbarium material and literature, we compiled trait information for each tree species, focusing on dispersal mode and seed size. 4. Disturbance reduced tree diversity and increased the proportion of lower wood-density and smaller-seeded tree species in study plots. Unexpectedly, disturbance also increased the proportion of stems with seeds that are ingested by animals and reduced those dispersed by other mechanisms (e.g. wind). Older secondary forests had functionally similar plant communities to the most heavily disturbed primary forests. 5. Synthesis. Anthropogenic disturbance has major effects on the seed traits of tree communities, with implications for mutualistic interactions with animals. The higher importance of animal-mediated seed dispersal in disturbed and recovering forests highlights the importance of avoiding defaunation or promoting faunal recovery. The changes in mean seed width suggest larger vertebrates hold especially important functional roles in these human-modified forests. Monitoring fruit and seed traits can provide a valuable indicator of ecosystem condition, emphasising the importance of developing a comprehensive plant traits database for the Amazon and other biomes.

This spreadsheet contains three tabs to present the data used in the article 'A large-scale assessment of plant dispersal mode and seed traits across human-modified Amazonian forests' (Hawes et al. Journal of Ecology). The first tab, labelled Legend, describes the column headers for the next two tabs. The second tab, labelled Plots, contains predictor and response variables for each of the 230 forest plots surveyed. The third tab, labelled Species, contains fruit type, dispersal mode, seed width and wood density for each of the tree species recorded. Data on fruit and seed measurements from herbarium collections were also contributed to the TRY Plant Trait Database (Kattge et al. 2020).