The trees in the rainforest biomes have developed several adaptations to enable them to survive the conditions in the area. The rain forests receive an average of between 50 and 260 inches of rainfall annually (Denslow, 1987). This means that the plants in that area will need to adapt in order to ensure that they shed water in an efficient way.
Another problem that may be encountered by rainforest flora is that the sunlight that reaches the plants on a lower canopy may be little. There are different layers of canopies. With every layer, there is a drop in the amount of sunlight that reaches the leaves. This means that the plants need to be adapted and they have to device ways of harnessing the little sunlight.
One adaptation of the rainforest trees is that they have drip tips on their leaves. This helps the leaves to drop off water from their leaves. The air is very humid and there is a tendency of leaves accumulating water. Another adaptation of the leaves is that they may have grooves on the leaves. This helps to increase the surface area to allow more water to be lost through transpiration.
The leaves of the trees in the rain forests may also be oily. This oily coating helps to shed off water from the leaves more efficiently and does not allow it to settle. The barks of these trees are usually thin and smooth. This is because they do not require thick barks to protect them from water loss (Herwitz, 1985). Since these plants receive plenty of water at all times, they do not require deep roots.
In order to absorb as much sunlight as possible, the plants have devised ways to increase efficiency. One adaptation is that the rainforest trees have broad leaves. This increases the surface area of the leaves to ensure that more sunlight reaches the leaves.
Another adaptation of the leaves is that some trees have leaf stalks that turn. This movement corresponds to the movement of the sun meaning that the leaves follow the direction of the sun and ensure that the maximum amount of light reaches the leaf surface at every moment.
Why these trees would not compete well in another biome
The rainforest trees have adaptations that limit them from being competitive in other biomes. For example, these trees would not be able to survive in a relatively dry area, let alone a desert. The broad leaves and the grooves on the leaves would increase water loss and that would become a hindrance to its survival. The large surface of the leaves would also mean that there is a larger surface area to allow for water loss.
Leaves of plant in dry areas need to have ways of reducing the surface area for water loss and this includes having small leaves and smaller stomata (Dolman, Gash, Robert, & Shuttleworth, 1991). The smooth, thin bark would also work against attempts towards water conservation because heat would be able to penetrate and water would be lost since the bark is thin.
Since the rainforest trees have shallow roots, such plants would not be able to survive in a dry area since they would not be able to reach the underground water. In dry areas, the groundwater level is usually lower and this means that roots need to go deeper. These plants would not be able to get water and they will simply dry up.
References
Denslow, J. (1987). Tropical rainforest gaps and tree species diversity. Annual Review of Ecology and Systematics, 18, 431-451.
Dolman, J., Gash, J., Robert, J., & Shuttleworth, J. (1991). Stomatal and surface conductance of tropical rainforest. Agricultural and Forest Meteorology, 54(2-4), 303-318.
Herwitz, S. (1985). Interception storage capacities of tropical rainforest canopy trees. Journal of Hydrology, 77(1-4), 237-252.