Context <p>Habitat fragmentation reduces core habitat and disrupts structural connectivity, ecosystem functioning and biodiversity persistence across human-modified landscapes. Fragmentation may be shaped not only by biophysical stressors but also by governance discontinuities created by administrative boundaries.</p> Objectives <p>We quantified four decades of forest change (1985–2023), assessed temporal trends in fragmentation and structural connectivity, and tested whether spatial variation in administrative boundary density and climate water deficit anomalies were associated with forest loss, fragmentation, and connectivity across northern Ethiopia at the contested intersection of Tigray, Amhara and Afar provinces.</p> Methods <p>We mapped land cover for 1985, 1994, 2009, and 2023 using Landsat Collection 2 Level 2 surface reflectance and Random Forest classifiers in Google Earth Engine. Forest was extracted as a binary layer for Morphological Spatial Pattern Analysis. We quantified core, edge and connector classes and graph-based indices to assess structural connectivity across different dispersal thresholds. Impacts of boundary density and climatic water deficit anomalies were evaluated using mixed effect models.</p> Results <p>Total forest cover declined from 4503 km² in 1985 to 1757 km² in 2023, a net loss of 61% with interior forest declining sharply (−81%). Connectivity decreased nonlinearly, with the largest decline between 1994 and 2009. Administrative boundary density emerged as the most consistent predictor of fragmentation and reduced connectivity, whereas climatic variables showed weak or inconsistent direct effects.</p> Conclusions <p>Forest cover and network connectivity declined strongly over the study periods, associated with higher administrative boundary density. Cross-jurisdiction coordination is therefore important for conserving the remaining habitat and rebuilding connectivity.</p>