Importance Value Index and Species Relative Contribution to Carbon Stocks in Savanna Ecosystems : Implications for Climate Change Mitigation and Forest Management in Patako Forest (Senegal)

Understanding species Importance Value Index (IVI) and contribution to carbon storage is key to improving knowledge on climate change mitigation and forest management models. The present study conducted in Patako Forest aims to investigate how species harvested for fuelwood and timber contributed to carbon sequestration. Data was collected using a stratified random sampling in 251 plots from different vegetation types. The results showed a good species richness of 102 species with significant variation of IVIs among vegetation types. Indeed, more than 90% of the IVIs was dominated by 21 species. It was dominated by fuelwood species in the savanna types and woodland, whereas timber species dominated in the gallery forest. This relative importance influenced species carbon storage contribution. In the shrub savanna 88.57% of carbon was stored by four species among which Combretum glutinosum (56.95%), with an IVI of 160.62 recorded an average of 7.67±1.30 t.C/ha. An inequitable carbon distribution was also recorded in tree savanna where five species counted about 80% of the carbon stock. Combretum glutinosum, Terminalia macroptera and Cordyla pinnata were the most frequent species and contributed about 72% of carbon stock in the woodland. In gallery forest, Khaya senegalensis stored the largest carbon stock (40.36±2.31 t.C/ha) with an IVI estimated at 38.52. The relations between IVI and species contribution to carbon storage should be taken into consideration for sustainable forest management in the context of climate change.