Woody vegetation on tropical inselbergs: floristic-structural characterization and aboveground carbon storage

The woody vegetation is an important plant community constituent of tropical inselbergs, yet it remains largely overlooked. These environments of high socio-cultural and ecological value face pressures in many places, mainly related to mining exploitation and fires. This study provides the first systematic overview of inselberg woody vegetation in the Brazilian Atlantic Forest. We used four inselbergs as models to characterize the composition and structure of the woody vegetation. In addition, the biomass and carbon storage were estimated using the general equations for tropical regions and carbon concentration values. Ten transects (50 m × 2 m) were systematically installed on each inselberg, and all woody plants with a diameter at breast height ≥ 5 cm were measured, registered, and identified. A total of 312 individuals belonging to 26 species, 23 genera, and 14 families were found. The Fabaceae family and the genus Eugenia (Myrtaceae) exhibited a higher richness. The woody community's diameters ranged from 5.0 to 116.9 cm (with a mean of 23.9 cm), and heights ranged from 1.7 to 16.0 m (with a mean of 6.2 m). All specialist lithophyte woody species found on inselbergs are wind-dispersed. Among the endemic species of the Atlantic Forest, four were endemic to inselbergs, with Pseudobombax petropolitanum and Wunderlichia azulensis being threatened. A few species dominated the communities: P. petropolitanum, Guapira opposita, Amburana cearensis, and Tabebuia reticulata. Carbon accumulated in aboveground biomass ranged from 14 to 48 Mg ha^-1, indicating variability in woody vegetation structure and growing conditions among inselbergs. Lastly, we highlight target species for potential use for inselberg vegetation restoration in stone mining areas in Atlantic Forest.