sentences:  South American "Polylepis" mountain forests are recognised as being one of the most endangered forest ecosystems in the world.During a reforestation project, D. Renison (University of Córdoba, Argentina) found that the germination of "Polylepis australis" stands decreases significantly with decreasing tree coverage.The first results of additional studies carried out in collaboration with Isabell Hensen (University of Halle, Germany) indicate that a clear negative correlation exists between the viability of seeds of "Polylepis australis" and the degree of human influence on the woodland stands.