Plant Life By Thomas McAlpine
Tropical rainforests have the kind of climate that can be described as hot and wet - it rains throughout the year, and the temperature almost never drops below 15oC. This would be conducive for plant growth. Rainforests mostly have large biodiversity. People say that two-thirds of the flowering plants in the world will be found in the world's rainforests. It is also claimed that a lot of the medicinal plants we know of are first discovered in rainforests.
Overviewing the climatic conditions in a rainforest might have helped anyone to predict the kind of vegetation that is going to occur in a rainforest. The diversity of the tropical rainforest biome is huge, so that almost all kinds of plants are represented in tropical rainforests. Here are some examples of plant life in tropical rainforest:
· Emergent trees are 100 to 120 feet tall. They will form umbrella-shaped canopies these will grow above the canopy of the forest. These are going to have small pointed leaves.
· A closed canopy of 80-foot tall trees. Light is going to be available at the top and greatly diminished below it.
· A closed canopy of 60-foot tall trees. There is going to be high humidity and restricted air movement.
· Shrub layer. Very little light is available.
· There are litter and wet leaves at the bottom of the forest layer.
Here are dome more scientific ones:
· 1. Broad-leaf trees- this tree is very common form of vegetation in the tropical rainforest. The size of the leaves is an adaptation shown by the trees. As very little sunlight reaches the forest, the trees have been able to adapted to maximize the surface area of the leave to absorb as much of sunlight as possible
· 2. Vines and Lianas- Lianas are woody creepers. It has been claimed that the rainforests are home to more than 2500 species of creepers. The vines and creepers found here are usually dubbed 'strangler'. They use a strong and tall tree as the host plant and ascend up the tree.
· 3. Epiphytes- Epiphytes also grow on host trees. However, the biggest difference between a strangler and an epiphyte is that a strangler has been rooted down to the forest floor and derives nutrition from the soil. An epiphyte, on the other hand, is a parasitic plant that would send its roots into the host plant to derive nutrients.
· 4. Saprophytes- Saprophytes are those species that survive on dead decaying matter by being able to deriving nutrition from it. Since the persistent heat and moisture in the rainforests accelerates the decay of dead plant matter, a number of saprophytic plants species have also been seen in rainforests.
Now you are also wondering what type of adaptions the plants have that allows them to survive in the tropical rainforest.
· Majority of the tropical rainforest plants have a smooth and thin bark. This is because, they are already exposed to warm, humid and wet conditions. Therefore the rainforest plants don’t need conservation of moisture, which is so in other tropical plants.
· Based on the plant growth habit, there are four strata in the tropical rainforest biome. Starting from the top, the first is called emergent layer, second is canopy layer, third is understory layer and the last forest floor.
· The trees in the emergent layer measure a height of about 100-140 feet, and receive limited sunlight. They show umbrella growth habit and develop maximum branches in the top portion. These tall trees are adapted for strong winds and exposure to hot conditions.
· The second stratum is the canopy layer of the rainforest, which represents broad-leaved trees of about 90 feet height. They are mostly of evergreen types and form a dense layer just below the emergent trees.
· The understory or lower canopy layer receives minimal light, less air circulation and very high humidity. Hence, shade loving, tropical rainforest plants of about 60 feet height grow here.
· The bottom layer of the forest floor, which hardly receives 2% light. As a consequence, there is hardly a single plant in this layer. Covered by leaves and plant parts, the forest floor is a rich source of humus.
· Another amazing fact is the development of buttresses. These are nothing but ridges formed at the base of large trees, which increase the plant surface area, and serve as supporting structure.
· In addition to buttresses, some huge trees have stilt roots. These again support the tropical rainforest plants that have shallow roots.
· In general, the foliage of tropical rainforest plants is large, thick and waxy. These features help them withstand heavy raindrops falling on the leaves. Also, some of the plant leaves possess 'drip tips', which again allow quick draining off the raindrops.
· The liana is a common plant of the tropical rainforest biome. This vine twines these tall trees and reaches the top height, where it receives sunlight for food production. Likewise, there are orchids and epiphytes that attach to the tall plants at specific heights.
· Irrespective of the height, the tropical rainforest plants have a shallow root system. This is because, much of the plant nutrients are accumulated in the rainforest floor and immediately at the bottom soil layer. Hence, they do not need deep penetration for deriving nutrients.