Abstract
Tropical moist forests are threatened by global changes, leading to an increase in degraded forest areas. A little-known yet widespread forest type in central Africa, the Marantaceae forests, presents a degraded appearance due to its open canopy and lack of tree regeneration caused by a dense understory of giant herbs. This thesis investigates the mechanisms behind the persistence and expansion of these forests in northern Congo using diverse approaches from landscape scale to tree stand and individual scales, based on satellite images, field inventories, vegetation and soil sampling, genetic analyses and a planting experiment. The results show that Marantaceae forests are significantly associated with fire and other disturbances. They maintain and expand thanks to giant herb extreme competitiveness and adaptive reproductive strategy. This thesis proposes ecological mechanisms explaining Marantaceae forest dynamics and highlights the importance of monitoring them in the future.