Prosopis juliflora, a highly invasive shrub, is spreading rapidly in Marigat sub-county (Kenya). This indicates that sustainable land management (SLM) practices, which could help controlling this weed, are either not adopted or are discontinued after a short while, thus blazing the trail for Prosopis. However, the absence of invasion in some areas shows that there are land users who have implemented SLM practices successfully.

Using satellite images covering the period from 1988 to 2016, PhD student Beatrice Adoyo identified three main types of spatial-temporal invasion trajectories that show widely diverging success in managing Prosopis (see map below):

• Areas that have remained invaded since initial invasion: SLM practices have never been implemented; this is the dominant trajectory
• Areas that are Prosopis free since initial clearance: SLM practices have been implemented consistently giving no chance to re-invasion
• Re-invaded areas: SLM practices were implemented for a while but later abandoned

Prosopis juliflora trajectories in Marigat Sub-County, Baringo County, Kenya.

Beatrice gathered information from land users on different social, political, environmental and economic drivers associated with these trajectories. Preliminary findings show that continuous clearance of Prosopis is primarily linked to active land use, for example through continuous cultivation. Constant invasion is associated with ineffective SLM practices such as the above-ground cutting of Prosopis for charcoal production, which facilitates coppicing and the formation of dense thickets. Further analysis of drivers will be useful to determine strategies to support the uptake and continuous use of SLM practices aimed at controlling the spread of Prosopis.