Background and aims – Eighty per cent of Gabon's territory is covered by forest with most species inventory work focused on these areas. However, herbaceous open vegetation types are abundant in this country and can be found in savannas on the coast, in the centre and in the south, and on inselbergs. The species diversity patterns of these habitats remain largely unexplored yet are targeted for both conservation and development. Here, we evaluate the floristic diversity of savannas in Gabon, their affinities with the inselberg open vegetation, and their contribution to the national park system in Gabon, which is currently undergoing a gap analysis. We then use a case study from the Batéké Plateaux to demonstrate species rarity in a single savanna.
Materials and methods – Species presence in the grassy formations of the savannas in Loango, Lopé, Pongara, and Plateaux Batéké national parks and in Kum inselberg is compared using ordination and clustering based on a similarity matrix (Sørensen index). For the Batéké Plateaux savannas, the species rarity and distributions are assessed using Star ratings.
Key results – The species in the open herbaceous vegetation in Gabon account for at least 11% of the total flora of the country (508 species out of 4,710). Except for the coastal savannas, all sites are highly dissimilar in floristic composition (Sørensen index 0.065–0.26) and no dominant savanna type occurs within the dataset. The inselberg site is the most dissimilar and constitutes a separate vegetation unit. Most savanna species of the Batéké Plateaux area are widely distributed, but not weedy. A few are extremely rare and are linked with moist habitats, substrate, and fire occurrence. Our results show the diversity and the conservation value of open, herbaceous habitats. Currently, the Gabonese National Park network is partly protecting the savanna and inselberg vegetation. However, several areas remain un-assessed and merit further exploration.