Factors affecting the dynamics of tree diversity in agroforestry parklands of cereal and cotton farming systems in Burkina Faso

摘要

Despite their socio-economic and ecological role, many studies have shown that the parklands are degrading very rapidly. Therefore, there is a need to undertake restoration actions for both production and environmental services. To do so, there is a need to identify factors that are affecting the dynamics of parkland systems. The present study aimed at characterizing and quantifying tree diversity of parkland systems taking into consideration the household’s wealth status, land uses, market access and the type of farming system (cereal based on the “Plateau Central” and cotton based in “Boucle du Mouhoun”). Six villages (Kienfangué, Ipelcé, and Kuizili with easy access to the market and, Karang-Tanghin, Nionsna and Targho with poor access to the market) in the “Plateau Central” and six villages (Bondoukuy, Ouahabou and Yaho with easy access to the market and, Dora, Fakéna and Mamou with poor access to the market) in “Boucle du Mouhoun” were studied. In each village, the Participatory Analysis of Poverty and Livelihood Dynamics method was used by rural farmers to rank farmer households of their communities and that gave three groups of wealth status that are poor, fairly well-off and well-off. Five households representing each of the three wealth groups in each village, giving a total of 15 households per village, were randomly selected by wealth group. Tree/shrub inventories were conducted in all land use types (house fields, village fields and bush fields) of the 180 selected households for the 12 studied sites. The number of species in the different land use types ranged from 96 to 102, but the majority of species were represented by less than 10 individuals. This indicates the selection effect made by the farmers to the parklands. Land use and farming system showed a clear effect on tree diversity in parklands. The effect of accessibility to market was evident in some cases whereas wealth status did not show any effect. Despite the statistical significant effect of farming system and land use type, the ANOVA models accounted for relatively little variation, indicating that other factors may contribute to tree diversity in parkland systems. The most threatened species were Adansonia digitata, Afzelia africana, Bombax costatum, Celtis integrifolia, Ficus asperifolia, Ficus iteophylla, Lannea velutina, and Parkia biglobosa. These species were represented in the largest diameter class (≥80 cm) or showed very few individuals in the different diameter classes. Due to the increasing degradation of the parklands, a domestication and conservation strategy of key threatened species needs to be developed and implemented with the participation of local communities.