High altitude forests are very important for local livelihood in the vulnerable environment of the densely populated tropical highlands. Humans need the ecosystem services of the forest and directly impact the forest through livestock herding, fire and wood harvesting. Nevertheless, temperature sensitive treelines in the tropics are scarcely investigated in comparison to higher northern latitudes. In this study the Erica arborea L. treeline is studied in a tropical mountain in the North Ethiopian highlands: Lib Amba of the Abune Yosef Mt. range (12°04’N, 39°22’E, 3993 m a.s.l.). The present treeline and forest cover was recorded by high resolution satellite imagery from Google Maps and field data (2010-2013), while historical forest cover was studied from aerial photographs (1965-1982) and repeat photography (1917-2013). The aerial and satellite images were orthorectified and classified in forest/non-forest binary maps. The binary forest layers were used to detect forest cover change and treeline dynamics by image differencing between the three time layers (1965-1982-2010). These maps and a terrestrial photograph indicate two periods of deforestation (1917-1965 and 1982-2013), whereas the forest cover was stable between 1965 and 1982. Deforestation was especially severe (with 63%) between 1982 and 2010, associated with a population increase from 77 to 153 inhabitants per square km. There is significant evidence that the elevation of the Erica arborea L. treeline increased 7 to 15 vertical meter between 1965 and 2010, in an area with decreasing anthropo-zoogenic pressure. This article is protected by copyright. All rights reserved.