Loja, Ecuador

The Reserva Biológica San Francisco (RBSF, 3◦58 S, 79◦04 W) is part of the biosphere reserve Podocarpus – El
Condor, located on the eastern slopes of the Andes in southern Ecuador within one of the world’s biodiversity hotspots. The forest reserve stretches from 1800 up to 3200 m above sea level (m asl) and is characterized by steep slopes (average slope 32◦, maximum slope 70◦) and deeply incised valleys. The RBSF is very rich in tree species, with more than 280 species identified so far in the 1000 ha area. The forest can be classified as evergreen montane forest and divided into four forest types with distinct structure and species composition. Below 2100 m asl we distinguish ridge and ravine forest, the two remaining forest types are located at higher elevations and the tree line is reached at 2700–2800 m asl. In this study we focus on the ridge forest (1900–2100 m asl). The ridge forest has lower basal area and also a lower canopy height (15–20 m) but higher tree den-sity compared to the ravine forest, where the canopy reaches up to 35 m. With approximately 70 tree species, the ridge forest is not as species-rich as the ravine forest. One interesting characteristic of the ridge forest is the high abundance of (relatively) fast growing species even in the climax stage. At higher elevations canopy height and species richness decrease.

Within the RBSF, shallow landslides are a main source of natural disturbance; up to 3% of the area is covered with visible traces of landslides. Most slides are shallow translational slides; in some slide events only the aboveground vegetation is removed. Landslide events alter the forest structure in a dramatic way – usually all vegetation on top of the landslide surface is removed (see Fig. 1). Narrow bands of vegetation slip downwards and leave bare areas of approximately 10–30 m width and 20–100 m length

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