Tropical rain forest, architecture, silvigenesis and diversity

Roelof A. A. Oldeman

Summary

1. Tropical rain forest architecture and dynamics may be analysed into three integration levels […]: (i) the eco-unit or regeneration unit, (ii) the chrono-unit or developmental mosaic and (iii) the silvatic unit or successional mosaic. Architecture is the complex of forms relevant to one integration level. Measured profile diagrams provide base data.

2. An eco-unit is a vegetation unit which has started to grow on one surface at one moment […].

3. A chrono-unit is the minimal surface to include all phases (aggrading, steady-state and degrading) of one specific eco-unit […].

4. A silvatic unit includes chrono-units of all eco-unit types on one site. Silvigenesis is the preferred term for the complex of forest-shaping processes, only some of which are clearly successional […].

5. Eco-unit diversity and environmental gradients between eco-units co-determine the range of spatial niches, and hence the potential species diversity. New eco-units which appear during the degrading phases of one eco-unit are either smaller because all trees do not fall at the same time, or larger if a catastrophe interferes. The ultimate and smallest eco-unit is the ‘chablis’ or one-tree gap of the old rain forest. The inverse relationship suggested between eco-unit size and diversity appears to hold true when moving away from lowland tropical rain forest to less hospitable environments: eco-unit size increases while diversity decreases.

Fonte: Oldeman, R. A. A. 1983. In: Sutton, S. L. & mais 2, eds. Tropical rain forest: ecology and management. Oxford, Blackwell.