Resumen
- Highlights: • Information was gathered on the nature and value of gallery forests. • The natural dynamics and current uses made of gallery forests were assessed. • “The possible threats from land use intensification were identified. Objectives: The objective was to describe the composition, structure, and functioning of gallery forests in the Yucao watershed of the Colombian savannas, south of the Meta River. Methods: The start of the project was reported last year (CIAT 1997b, p. 3-6.). The data collected in 1996-97 fieldwork were analyzed. Further data including surveys from 1997-98 were incorporated. Composition: The gallery forests are low-statured forests with rather open canopies and high stem density (Table 5 of2.1.1). Forest composition and structure vary along ecological gradients of which the most important is related to the hydrological regime. In eighty 20 x 20-m plots (3.2 ha), 147 tree species (DBH>5 cm) were found. The palm-dominated forest is the least diverse (1-4 species); the other forests contain an average of 20 species per 400-m2 plot. The tree flora of this region is not exclusive to savanna forests. Zero to few endemics are found, and most species are broadly distributed geographically. Most species of the Yucao forests occur in the humid forests of western South America, and many are distributed throughout tropical South America, or South and Central America The affinity with the flora of dry tropical forests is relatively small. The gallery forests can therefore be considered as extensions of humid forests into the seasonally dry savanna environment. The relatively high species richness of gallery forests suggests that the current level of isolation is either too recent or not severe enough to have had a large deleterious effect on diversity.