Tree biodiversity, land dynamics and farmers strategies on the agricultural frontier of southwesthern Burkina Faso

In the sub-humid part of Burkina Faso, population growth, migrations and new marketing opportunities have induced rapid land-use changes and social reorganization, leading to new approaches to natural resource management. The objective of this study was to evaluate tree biodiversity parameters in agroforestry parklands (scattered trees in crop land) as population increases and fallows become shorter. Out of about 100 tree species existing in the area, and 50 commonly found in traditional parklands, only 3 indigenous and 2 non-native species hold a significant importance for farmers, all for their fruits. No indigenous tree species are planted, but a few are protected when clearing the land. Planted cashew nut orchards develop rapidly and are seen as a land tenure guarantee and an important source of income. Given these facts, the perspectives for tree biodiversity management in farmers' land may appear bleak. Yet, the importance given by farmers to specific tree products demonstrates that trees do play a pa t in land development and farmers' strategies. Existing practices of farmers show potential for improved land-use and spatial patterning of the land, as revealed by emerging parklands and orchards. Our data do not confirm common statements that migrant farmers do not manage the land as sustainably as native farmers do. Rather than trying to conserve tree biodiversity as it is, researchers and developers should identify with farmers the complementarities between trees and farms and promote tree biodiversity through existing practices. (Résumé d'auteur