Composition and density of soil seed bank in Afar Region, Northeast Ethiopia

Abstract Background: The changeover from seed to plant is a fundamental scheme shaping plant community structure and dynamics. Persistent soil seed banks are significant as it distributes regeneration and succession throughout the year in the vegetation ecosystems following disturbances. Objectives: The aims of our study were to analyze status of composition and density of soil seed banks (SBs) in West Afar Region, Ethiopia, and effects of Prosopis juliflora (Prosopis) on spatial distribution and densities of SBs. Methodology: Soil samples were collected under the Prosopis canopies and non-invaded open grazing lands from area of 15cm x 15cm and soil layers of 0-3cm, 3-6cm and 6-9cm. Findings: It was found that SBs had shown significant variations by districts (χ2 = 5.5, P =0.02) and soil layers (χ2 = 10.5, P =0.01). But, habitats did not show significant effects on SBs (χ2 = 2.3, P =0.13). Higher density of SBs 7065, 8978, and 8444seeds/m2, respectively were recovered from the soil depths of 0-3, 3-6, and 6-9cm at Teru district. On the other hand, lower densities of 311, 0, and 44seeds/m2, respectively SBs were recovered from the soil depths of 0-3, 3-6, and 6-9cm were at Yalo district. Furthermore, SBs under the canopy of Prosopis were less by 93.5% than non-invaded open grazing lands in 0-3cm soil depth. Meanwhile, SBs in 3-6cm soil depth were higher by 79% in non-invaded Prosopis than invaded areas at Teru district. Conclusions: The overall low density of the SBs in the study areas had implications of poor range land quality for animals to feed on and consequently affects the livelihood incomes obtained from livestock of pastoralists. Thus, conservation of grazing lands, re-seeding of grazing lands, and management of the invasion of the Prosopis are vital measure to sustain the grazing areas in the region.