The influence of water proximity on land cover, tree species and tree funtionalities in a small-holder agroforestry system : a minor field study in Trans Nzoia County, NW Kenya

Abstract

A large and rapidly growing population in Kenya together with increasing demands put heavy pressure on the country’s resources. Primary to produce enough food but also to meet other needs such as access to timber and firewood. A large part of the population relies on yields from their own farming for their survival. The farms are generally small and the needs many which makes it important to get out as much as possible from a limited space. A common alternative is to plant trees and implement agroforestry. Agroforestry trees are often multi-functional, but they have different main usages and the high competition of land force the farmers to select how they use their land and their agroforestry systems carefully. It is important to remember that even though tree planting can contribute to food security; it is not always a direct source of food and trees also consumes resources such as nutrients and water. The aim of this study was to investigate how water proximity influences land cover, the distribution of tree species, and the main functions of the trees (Fiber, Firewood, Fodder or Fruit) in an agro-ecosystem in Hututu settlement, Trans Nzoia County, Kenya. Further, land cover maps over five settlements in Trans Nzoia were ground truthed. User’s accuracy, producer’s accuracy, overall accuracy, and Kappa value were calculated and evaluated for all maps. Through these results together with interviews and field observations was the study area in Hututu settlement selected and a detailed land cover map created. The results show that water proximity has an influence on land cover to some degree, but since small-scale farmers mainly tries to meet their own needs can maize and beans, the staple food in Kenya, be seen everywhere. The same result can be seen for tree species, and especially when Eucalyptus is considered which the most common tree species in the area is. Tree functionality is indirectly influenced by water proximity and it can be concluded that trees that requires less management often grow close to the water courses. Further, the land cover classes Woodland and Shrubland occur more frequently in these areas. After field observations, the proximity to buildings was also investigated as an alternative factor that influences land cover and how trees are distributed. By that investigation it could be seen that woody land cover classes have a positive relationship to closeness to buildings and that fruit trees generally are planted close to the houses