Assessment of Riparian Vegetation Condition and Buffer Zone Management in Agricultural Watersheds of Sokoto State

Riparian buffer zones are critical for maintaining watershed health in agricultural landscapes, and professional assessment of their vegetation condition in Sokoto State, North West Nigeria, provides evidence for improved land and water management. This study assessed the vegetation condition, species composition, and buffer zone effectiveness of riparian areas in three agricultural watersheds of Sokoto State: Rima River watershed (Sokoto metropolis), Bunsuru River watershed (Sabon Birni), and Gagare River watershed (Gada). Belt transects (50m x 10m) perpendicular to river channels were surveyed at 5 sites per watershed, recording all vascular plant species, canopy cover, bare ground percentage, and bank erosion indicators. Buffer zone width was measured and compared to the FAO recommended minimum of 10m on each bank. Overall vegetation condition scores were assigned using a modified Riparian Vegetation Assessment Protocol. Results showed that mean buffer vegetation cover was 44% across all sites, well below the 70% threshold for effective buffering. Buffer zone width was below the 10m FAO minimum at 67% of surveyed sites. Native tree cover was below 15% in agricultural watershed riparian zones, with most remnant native trees being Acacia nilotica and Faidherbia albida. Exotic grasses were prevalent at 78% of sites. Vegetation condition was significantly better at sites where seasonal flooding restricted agricultural access. The study recommends legally enforced riparian buffer zones of minimum 20m on agricultural watersheds in Sokoto State, with enrichment planting of drought-tolerant native trees by the Sokoto State Agricultural Development Programme.

Keywords: riparian vegetation, buffer zone, watershed management, Sokoto State, agricultural landscape