Range use and dynamics in the agropastoral system of southeastern Kenya

Abstract

Occurrence of equilibrium and non equilibrium system dynamics in semiarid environmenls present serious management challenges. ln these areas, resource management strategies are increasingly based on equilibrium rather than non equilibrium dynarnics that assume simple systern dynamics and strong coupiinE of a.imal-plant responses. This ffiar:agemeni approach underlies increasing trends of range degradation and low livestock productivity in these environments. To reverse these trends dictates greater understanding and alignment of grazing resource extraction strategies in space and tlme to prevailing system dynamics behaviour. ln ihis study, range use patterns by free ranging herds under agropastoral herding were studied in two cycles of four consecutive grazing periods, in semiarid southeastern Kenya. The bites count and herd locations per area methods were used. While grazing thresholds in the system were derived from biweekly sward biomass measured by the qiadrant technique in the growing period and stocking rales applied to a growth-consumption iate model. The analysis tested the responsiveness of the agropastoral herding strategies to the predominant system dynamics in the area. ln this environment, high rainfall variability ranging from 71 to gB% is experienced across years and seasons, pointing to non-equilibrium dynamics in the system. The agropasloraiisis practiced seasonal range use and tracking strategies. During the dry season, areas of concentrated drainage; river valleys, bottomlands and ephemeral drainage ways absorbed a greater grazing load, taking 57.1 to 60% of the grazing time by the animals. ln Contrast, areas of limiGd moisture concenlration, the open sandylclay plains, were rnainly exploited in the wet season and accounted for 52.6 to 55.6% of the grazing time. The agropastoralists tracked forage availability through use of rnultispecies livesicck (cattle, goats and sheep) that exploited different grazing resources in space and lime. These range use patterns and strategies tend to stabilize nutrient and energy flow to livestock and thus productivity throughout the seasons. Based on the growth-consumption rite model, grazing thresllglds in the system are achieved at 13800, 13000,4000 and 12300,4600 and 12000, anO 6olo anO 11000 kgha-' of grass biomass aL,2.5,5,7,8 and 10 TLUha-1, respectively. 7 TLUha-1 represent the upper stocking rate limit in the system during the growing period. In this system, resource use strategies are in line with the predominantly non-equilibrium system behaviour. However, sedentary ta-nd use interventions and limiting farm sizes that restrict livestock mobility and negatively afflct grazing resource diversity will undermine system stability and sustainable Iivestock production in the area.