This database is the product of the 2ndFOR collaborative research network on secondary forests. The database contains total basal area data (in m2 ha-1) of legume trees (Leguminosae) for 1207 secondary forest plots differing in time since abandonment. The plots belong to different chonosequence studies. For a description of the database, see Gei et al. 2018. Legume Abundance Along Successional And Rainfall Gradients In Neotropical Forests. Nature Ecology and Evolution. The file "Legume basal area 2ndFOR data.csv" contains the following variables: Chronosequence: name of the chronosequence site Age: age of the plot (in years), "OG" indicates old-growth forest of unknown age LBA: total basal area of legume trees (Leguminosae) of the plot in m2 ha-1 Reference: a citation for the chronosequence study, if available PI/contact person: name(s) of the principal investigator(s) or contact person(s) for the chronosequence study.