Assessing Impacts of Cattle Grazing on Vegetation Cover in Nasarawa State Savanna

Overgrazing and the intensification of livestock pressure on Guinea Savanna vegetation in Nasarawa State have generated significant land degradation concerns in Nigeria's North Central geopolitical zone, contributing to conflict over shrinking pasture resources and undermining ecological services that savanna ecosystems provide. This study assesses the impact of cattle grazing on vegetation cover across three grazing intensity zones in Nasarawa State using a combination of remote sensing analysis and field vegetation surveys. NDVI values derived from Sentinel-2 imagery were computed for 2018 and 2023 at 120 sampling locations classified into heavy, moderate, and light grazing intensity zones based on cattle route and water point proximity. Field vegetation surveys at each location measured grass species diversity, basal cover, ground litter, and bare soil fraction using modified Daubenmire quadrat sampling. Livestock density estimates were derived from community census data obtained from the Nasarawa State Ministry of Agriculture. Results indicate significant vegetation cover decline in heavily grazed zones relative to lightly grazed areas, with mean NDVI reductions of 0.18 and bare soil fractions averaging 47 percent compared to 11 percent in lightly grazed zones. Species richness is lowest and forb dominance highest in heavily grazed locations, reflecting transition toward less palatable vegetation assemblages. The study recommends rotational grazing systems, water point dispersal to relieve pressure on localised areas, and investment in improved pasture management through the Nasarawa State Livestock Development Programme. Keywords: overgrazing, vegetation degradation, Nasarawa State, savanna, North Central Nigeria.