Environmental Engineering Reference
In-Depth Information
hectare, tropical forests often include as many as 100 (Figure 28.4). Studies in
Amazonian Ecuador found 307 tree species within one hectare, though 76 per cent
Figure 28.4
Species/area curves for
tropical forest tree species with a
minimum diameter of 0ยท1 m in selected
locations.
of the species present had only one or two specimens. In general, there is a positive
relationship between mean annual rainfall and the number of species. This has
advantages and disadvantages when exploitation of tropical forests takes place. Most
species are evergreen, and those that are leafless for any period shed their leaves at
irregular intervals. There is no autumn in the sense of the leaffall period of deciduous
forests. Intense competition and the diversity of plants lead to complex structuring of the
forest, with five or more strata recognizable and a significant epiphytic component
(Figure 28.5). Species diversity or richness is high, but species' distributions are often
restricted to small areas (Plate 28.2).
