Régénération assistée du karité (Vitellaria paradoxa C. F. Gaertn.) dans les parcs agroforestiers au Burkina Faso

Le karité (Vitellaria paradoxa C. F. Gaertn.) présente une importance sociale, culturelle, économique et alimentaire pour le Burkina Faso où il occupe la quatrième place dans les produits d’exportation. La pérennité de cette espèce dont les populations rurales sont tributaires, est compromise par de multiples phénomènes dont le manque de régénération, les pratiques culturales et la coupe abusive du bois pour satisfaire les besoins énergétiques. L’objectif de cette étude est de proposer des méthodes adéquates pour rajeunir les parcs à karité au Burkina Faso. Cinq sites de recherche ont été choisis suivant un gradient phytogéographique : Sobaka, Noumoudara et Kakoumana (secteur sud soudanien), Gonsé (secteur nord soudanien) et Bouria (secteur sub sahélien). Les essais effectués dans chaque parcelle choisie, ont comporté trois répétitions et 7 traitements, représentés par les différentes techniques de régénération (plantation, transplantation, semis direct libre, semis dans les buissons, régénération naturelle assistéeRNA-, induction de drageon, induction de pousse adventive). Les résultats indiquent que le taux de survie de la régénération naturelle assistée est audessus de 70% après deux années de suivi. Les plantations et les semis directs dans les buissons sont aussi des techniques efficaces pour la régénération/restauration des parcs à karité, avec respectivement des taux de survie de 13,33% et 6,67% dans le secteur sub sahélien, 12,22% et 6% dans le nord soudanien, et 55,56% et 25,33% dans le sud soudanien après la troisième année de suivi. En conclusion, la régénération assistée est la technique la plus efficiente pour restaurer les parcs à karité. The Shea (Vitellaria paradoxa C. F. Gaertn.) is of enormous social, cultural, economic and nutritional importance for Burkina Faso where it ranks fourth in exports. The sustainability of this species on which rural populations depend is compromised by multiple phenomena, including the lack of regeneration of shea tree and the abusive cutting of wood to meet energy needs. This work aimed to propose adequate methods for rejuvenating shea parkland in Burkina Faso. Five sites distributed along a phytogeographic gradient were selected for tests : Sobaka, Noumoudara and Kakoumana (South-Sudanian phytogeographic zone), Gonsé (NorthSudanian phytogeographic zone) and Bouria (sub-Sahelian phytogeographic zone). The field trials included three repetitions by regeneration technique (planting, transplanting, direct sowing free, sowing in bushes and assisted natural regeneration -ANR-, sucker induction, induction of adventitious growth). The results indicate that the survival rate of assisted natural regeneration is above 70% after two years of follow-up. Planting and direct seeding in bushes are also effective techniques for the regeneration / restoration of shea tree parks with respectively survival rates of 13.33% and 6.67% in the sub sahelian sector, 12.22% and 6% in north sudanian, and 55.56% and 25.33% in south sudanian, after the third year of monitoring. In conclusion, in order to restore the shea parks, all seedlings regardless of their origins, will need to be assisted i

Long-term effect of forest and landscape restoration practices on soil organic carbon stock in semi-arid Burkina Faso

In semi-arid areas, forest and landscape restoration (FLR) practices are being implemented to reverse the land degradation process. The objective of this study was to investigate the long-term effect of FLR practices on soil organic carbon stock (SOCs) under different land uses in the semi-arid region of Burkina Faso. The study was conducted on degraded land under rehabilitation practices for 45, 27, 18 and 11 years, which were compared to similar land without specific rehabilitation measures. The soil was collected in 2018 in 35 sampling plots of 30 m x 30 m. Soil analysis concerned bulk density, soil particle size, soil pH, soil organic carbon content, and respiratory activity of microorganisms. SOCs increased by 150%, 98% and 29% over 0-10 cm depth in 45-, 27- and 11-year of FLR practices, and decreased by 6% in 18-year of FLR practices compared to their respective control. SOCs were not linearly increased with the duration of the implementation of FLR practices because the variation of SOCs depends on several other parameters such as soil texture, and types of combination of FLR practices. The highest SOCs were recorded for 27 years (9.5 t.ha-1) and 45 years (8.5 t.ha-1) of FLR practices. This study revealed the importance of including Assisted Natural Regeneration (ANR) as one of the combined FLR practices, for improvement of SOCs

A cost-benefit analysis of ecosystem services from restoring degraded soils to forest ecosystems in the Sahel

International audienceTechniques of degraded ecosystems restoration in the Sahel have largely contributed to slowing down desertification process. However, they are often very costly, requiring important manpower and financial resources. The economic benefits of such cases of land restoration are under-documented, especially in scientific literature. The aim of this study is to estimate the ecosystem benefits (market and non-market, direct and indirect) associated with changes in biodiversity induced by forest and landscape restoration (FLR) interventions in the Sahel, and to compare them with the costs of these interventions. Data has been compiled using individual and group surveys, floristic inventory, and existing literature. Ecosystem services framework has been used to structure the analysis. Financial and economic cost-benefit analysis have been compiled, based on the historical case of the managed Gourga forest (Ouahigouya, North Burkina Faso), to estimate whether FLR brings benefits greater than it costs. The results show that restoration of the site is profitable over the first ten years thanks to farming activities, becoming unprofitable in years 11–45 after farming is completely stopped. This study opens up new prospects for improved design of FLR in the Sahel