Nyssen's research showed that high levels of soil loss in the Ethiopian highlands are caused by a combination of erosive rainfall, steep slopes (as a consequence of rapid tectonic uplift during Pliocene and Pleistocene), and impacts of deforestation, overgrazing, an agricultural system where the open-field system dominates, and the aftermath of povery induced by the feudalism. He further studied in the Ethiopian highlands how the high density of soil and water conservation structures led to land resilience.