COS 129-5 - Forest management effects on species richness, tree diversity and functional composition of sudanian forest

Background/Question/Methods

All over the world, human disturbances have led to the degradation of forests and a drastic reduction in their area. In Africa, forest management based essentially on the selective cutting of trees remains the main forest management strategy. However, the effects of management practices on biodiversity remain insufficiently known. We investigated how the taxonomic diversity and functional diversity of woody species responded to four types of forests in the Sudanian area of Senegal: 1) formerly managed forests, 2) recently managed forests, 3) community managed forests and 4) unmanaged (exempt of official harvest) forests, while considering mature trees and natural regeneration separately. We collected floristic data on five unmanaged forests, four formerly managed forests, seven recently managed forests and four managed community forests, as well as functional traits for 20 species with high socio-economic value. We calculated the species richness and diversity indices and fitted linear models to estimate the differences between the different forest types for each index. We also analyzed how species’ functional traits affect the abundance of their regeneration in the different forest management types.

Results/Conclusions

In total, 26,009 young and adult trees grouped into 183 species were identified. We found for all age classes that unmanaged forests contained significantly more species but were as diverse as managed forests. Species composition was different between forests, and high-value species were more present in unmanaged forests. The absence of some mid-diameter classes and the high presence of small-diameter individuals in recently managed forests and managed community forests was notable even though aboveground and root carbon stocks were virtually the same. Among functional traits, seedling reproduction, wood density, and leaf area were more sensitive to forest management. Our results show that forest management in the region affects species richness and functional composition more than species diversity.