Vertical Stratification - Tropical Rain Forest
In a tropical rain forest, vertical stratification is very clearly seen. In addition to the different layers described above, there are lianas and climbers that twine around the .trees. A forest with four or five strata can support a greater diversity of life forms as compared to grassland with only two strata. Stratification is also seen in the underground plant parts, that is, the root and the rhizome systems. Root systems of different plant species tap moisture and nutrients from different soil depths. This enables them to avoid competition and too much exploitation of a particular soil layer.
Coming back to the above-ground parts of vegetation, the canopy which is the primary site of energy fixation, it has a major influence on the rest of the forest community.
A canopy is said to be open when considerable sunlight reaches the lower layers. In such cases the shrubs and understory tree strata are well developed. In a closed forest most of the sunlight is intercepted by tree canopies. The understory plants remain deprived of direct sunlight consequently the lower strata is comprised of shade tolerant species with poor growth of herbaceous layer. In such situations species requiring intense sunlight are absent or flourish only in the gaps created by the death of top canopy trees.