WP4. Analysing past changes in vegetation, disturbance and environmental variables from present to 4000 BP
© Jean-François Gillet
Long-term ecological records are essential to understand past responses of vegetation to climate change and human activity. The records can then be used to determine baselines of the natural variability of the rainforest ecosystem, its response to climate variations, and resilience to disturbance including human activity.
Previous paleoecological works indicate that TMF extension in Central Africa has experienced, over the last millennia, dramatic changes related to variations in rainfall patterns or to anthropogenic pressure. It is believed that these disturbances still influence today's repartition of forests and savannas, and species distributions. There is an ongoing debate over the origin – human or climatic – characterising light-demanding canopy plants in large TMF areas: is there a recovery phase from past anthropogenic disturbances or from a dry episode contemporary with the European Little Ice Age?
Activities
Since 4000 BP, determine:
- The chronology of climate change and human occupation at the region scale;
- The chronology and amplitude of vegetation changes at the region scale.
Then study, along selected transects, whether and when the vegetation has been influenced by ancient disturbances.
Expected results
Results will provide additional elements to evaluate our core hypotheses, in particular we will test whether: 1) main changes experienced by TMFs in the region are primarily linked with change in climate patterns, mediated by soil conditions, directly by modifying water availability, and indirectly by favouring human disturbances or by enhancing their effects; 2) contemporary TMFs are still recovering from these changes and are slowly adapting to present climatic conditions.