ABSTRACT
This chapter focuses on humid tropical montane forests at and above 3000 m and on the forest-grassland transition in the northern portion of the Bolivian Andes. The eastern tropical Andes contain some of the world’s richest plant communities. However, knowledge of the magnitude and spatial distribution of this plant diversity is fragmentary. Among birds, variation of endemism along the Andean timberline from Ecuador to Bolivia has been linked to ecoclimatic stability, i.e. the local topographically determined moderation of climatic extremes such as droughts and cold air influxes. The closed upper timberline on the humid eastern Andean slope in Bolivia is located at about 3300–3600 m. The closed upper timberline is gradually pushed down, while remnant Polylepis forest patches survive in sheltered sites, such as ravines, rock faces, and boulder slopes. Timberline forest destruction probably started long before the Spanish conquest.
