Monitoring Vegetation Cover Change in the Sahel Zone of Katsina State Using Remote Sensing

Vegetation cover in Nigeria's Sahel zone is highly sensitive to interannual rainfall variability and human pressure from cultivation and fuelwood extraction, making continuous monitoring essential for managing dryland ecosystem services. This study monitors temporal changes in vegetation cover in the Sahel zone of Katsina State between 2014 and 2024 using normalised difference vegetation index derived from MODIS Terra satellite products. Time series analysis of monthly NDVI composites was conducted to identify trends, seasonal patterns, and anomaly years. Rainfall data from the Nigeria Meteorological Agency were correlated with vegetation response to disaggregate climate-driven from human-driven change signals. Field verification involved ground cover assessment at 45 sample plots using line intercept transects. Findings reveal a slight but statistically significant long-term greening trend in the northernmost districts, consistent with the pan-Sahel regreening phenomenon documented in recent literature. However, localised degradation patches are identified around high-density settlements and livestock watering points, where vegetation cover has declined by more than 25 percent. The correlation between rainfall and NDVI is strong at the zone level but weakens in districts with high cultivation intensity, indicating significant human modification of vegetation dynamics. The study recommends integration of these findings into Katsina State's state-wide land degradation neutrality assessment and the Great Green Wall initiative monitoring framework. Keywords: vegetation monitoring, NDVI, Sahel zone, Katsina State, land degradation.