Das Projekt "Ackerbaulich bedingte Brandrodungen als Ursache für Vegetationswandel und Bodenerosion im Bergwald von Bolivien" wird vom Umweltbundesamt gefördert und von Universität Zürich, Geographisches Institut durchgeführt. Within an integrated project of the Universities of La Paz (Bolivia) and Zurich, ecological investigations are realized since 1996. In the upper mountain forests near the cities of La Paz (in the so called yungas') and Cochabamba (the chapare') vegetation cover, soil erosion and pollen influx are studied in order to get local climatic information at altitudes of 1500-3200 m a.s.l. A decrease of forest areas is observed - as well as an increase of agricultural areas - even with slope inclinations of 40%, with many damages by soil erosion as a consequence. The humid climate with annual precipitation of 100-200 cm, however, is somehow protecting the area from large ecological impacts, because a secondary forest is coming up rapidly. On the other hand, the nearby region above 3200 m a.s.l. is semihumid to semiarid and strongly affected by soil degradation. The deforestation areas of the past centuries were localized by pollen analysis of near-surface soil samples.