Indigenous systems of management for regulating extraction of non-timber forest products (NTFP) have not been well documented in arid zone grazing lands. Conservation projects have therefore lacked information on customary rights to trees, while they have enforced systems of tree resource management that often conflicted with the indigenous system. This study focused on the indigenous tree tenure system of the Turkana pastoralists called ekwar (plural ngikwarin). The indigenous tree management system in 15.4 km2 of the Turkwel River floodplain woodlands near Lodwar, Kenya was investigated. The study began in 1990 after impoundment of the Turkwel Gorge Dam. In 1990 and 1998, Turkana pastoralists were interviewed about the ekwar. In individual ngikwarin woody cover, wood volume and woody-plant density were measured, and wood extraction assessed in terms of stems and twigs removed by the pastoralists and the urban population of Lodwar. Intensity of charcoal burning was assessed in terms of the density of earthen kilns, and livestock impact in terms of browsing frequency on woody plants. Potential Acacia tortilis litter production was estimated and an ekwar quality index developed to describe woodland productivity conditions. Tree produce was shared with and leased to friends and relatives. Woody cover showed no significant changes, while woody-plant density and volume declined, over the 8-year period. The Turkana usually do not cut live trees, but use dead trees and dry tree-parts for making charcoal. Increased kiln density and increased extraction of tree-parts were considered to be indicative of increased pressure on the riverine woodlands. Livestock browsing did not seem to contribute to woodland degradation. However, decline in woody-plant density and volume might have contributed to the reduction of litter production of A. tortilis. Trends in woodlands in the floodplain might be associated with damming of the Turkwel River and local anthropogenic pressures. Also, the ekwar system of tree tenure seemed to be threatened by the official forestry policy that it be ignored. Incorporating the ekwar system into the forestry conservation policy may achieve sustainable use and improve conservation of the Turkwel River floodplain woodlands.