Disturbance regimes in Central African Rainforests
The Central African forest is the second largest contiguous forest area in the world, hosting the highest diversity of large mammals (Primack and Corlett 2005). Large areas of monodominant forest are typical (Primack and Corlett 2005), as well as the Marantaceae forest, where giant herbs of the Marantaceae family dominate the understory of an open canopy forest (Fay 1997). How is biodiversity and forest extent of this unique forest going to be affected in the future? It is projected to become drier in the west of the Congo basin and wetter in the east, though large uncertainties remain (James et al. 2013). The use of palaeoecological records is a promising approach to understand vegetation responses to past disturbances similar to those projected under future climate change scenarios (Willis et al. 2013). Pollen records have shown that a major decrease in primary forest trees occurred during the late Holocene linked to an extended dry season (Maley 2002). There is also evidence for past fires, especially in the last thousand years (Brncic et al. 2009). Nevertheless, earlier findings have relied on the analysis of individual cores, which does not take into account spatial variability. Also, the role of fire in shaping forest types and the origin of forest types such as Marantaceae or the monodominant forest is still unknown.
The aim of this project is to examine past vegetation dynamics of the Central African rainforest in response to fires and climate change in order to attempt to determine their spatial extent, their impact, and the resilience of the rainforest to such disturbances. Information obtained for this project will provide insights in possible threats from current fire dynamics and climate change processes. Based on palaeoecological records (fossil pollen, charcoal and phytoliths), the strength of this work is its combination of spatial and temporal scales, which is rarely achieved in most palaeoecological studies in tropical forest regions because long-term research sites are very limited.
The analysis focuses on 4 aspects:
- The spatial extent of forest-savanna mosaic and its changes trough time for the last 6000 years
- Fire history and its effects on forest types in the last 2500 years
- Forest responses to disturbances: History of Marantaceae forest
- History of monodominant Gilbertiodendron forest: What triggers monodominance?