This dataset was collected during the TOSCA HYPERBIO project supported by CNES, in collaboration with ONERA/DOTA and TETIS Lab. The FABAS forest is located in the “Vallées et Coteaux de Gascogne” (Haute-Garonne, France), belonging to the ZA PYGAR long-term socio-ecological research site (LTSER) (Ouin et al. 2021). The forest was sampled in 2019 to acquire a set of square plots in which the dominant tree species with their percentage of coverage at canopy level were estimated. A non-random sampling strategy was applied in order to select plots in forest stands of different composition (tree species), structure (heights), openness, and topography (steep or flat). We sampled a total of 44 plots. Each plot was defined as a square of 40 m x 40 m. Plots were located using a Garmin GPSMap 62st receiver (3–5 m accuracy) and distributed over forest stands. The surveys were carried out in april (19th, 23th, 24th, 26th), may (2nd, 9th) and july (18th) in 2019. For each plot, the % tree cover of the dominant tree species at canopy level was estimated by one or two observers with a minimum range of 5 %. A maximum of 5 dominant species were recorded. The total % of tree cover within each plot may not reach 100 % because of over-mixed species or uncovered areas. The % cover of understory vegetation was also recorded with no information on the species.