1. The extent (or lack) of phylogenetic signal for key ecological traits reveals the role of evolutionary processes on present-day ecosystem function and hints on future ecological trends under climate change scenarios. This approach has been applied to South American tropical moist forests, but not to the highly threatened seasonally dry tropical forests (SDTF), despite acknowledgement of their unique evolutionary history. To fill this knowledge gap, we investigated the legacy of evolutionary processes on vital ecological characteristics among SDTF trees: regional dominance, tree size and soil preference.

2. We used tree community data on 313 plots of SDTF (12.52 hectares) and locally collected soil data in central-eastern Brazil. For each assessed trait (three for regional dominance, three for tree size and nine for soil preference), we investigated the legacy of evolution using two different approaches: calculating the extent of phylogenetic signal and comparing the fit of four different models of evolution.

3. Aboveground woody biomass and tree size showed strong phylogenetic signal. Most of the SDTF biomass stock was concentrated in a few large-sized and closely related tree genera. Among the soil preference variables, only phosphorus displayed significant, albeit weak, phylogenetic signal.

4. Synthesis. Our study is the first to show that evolutionary constraints related to tree size significantly determine regional biomass stocks of SDTF in a few closely related tree lineages. This suggests that even isolated SDTF fragments with low taxonomic and phylogenetic diversity can play an important role in the global carbon cycle, storing disproportionally large amounts of carbon in trees that belong to high-biomass lineages. Whether these lineages also share climate change-induced mortality risk deserves future investigation, as they are largely responsible for the maintenance of regional SDTF biomass stocks.

This dataset is the result of multiple field trips carried out between 2009 and 2016 by members of the Laboratory of Phytogeography and Evolutionary Ecology, Department of Forest Sciences, Federal University of Lavras, Brazil. Tree community and soil data were pooled into the two spreadsheets presented here: one containing the variables related to ecological dominance, tree size and soil preference on the genus level and the other containing the same variables on the species level. We used these data to run phylogenetic signal analyses as described in the main text of the paper.