How has rainforest vegetation adapted to the climate?
Vegetation in the tropical rainforest has adapted to thrive in its hot, wet climate in a range of ways.
The rainforest has four distinct layers of plants with different adaptations. For example, plants in the highest layer (emergent) only have branches at their crown (where the most light reaches them), and plants in the under-canopy have large leaves to absorb as much light as possible to support photosynthesis.
In the tropical rainforest, most trees in the rainforest have wide buttress roots to support them as they grow incredibly tall (over 20-40m in some cases) as there is considerable competition for sunlight. In addition to this roots grow wide rather than deep because nutrients exist in the top layer of soil.
Epiphytes are plants that grow on the surface of another plant. They get their moisture and nutrients from the air, rain, water or debris accumulating around it.
Lianas (vines) grow around trees as they climb to reach sunlight.
Tree bark in the tropical rainforest is typically thin. This is because the temperature throughout the year is typically between 26-28°C. Therefore they do not need protection from the cold.
Plants drop their leaves gradually throughout the year, meaning they can go on growing all year round.
Many trees have smooth, think bark as there is no need to protect the trunk from cold temperatures. The smooth surface also allows water to run off efficiently to the soil so the tree can absorb the water.
Additionally, smooth trunks reduce the risk of epiphytes growing on a tree as they have nothing to attach themselves. This helps protect the tree from the risk of collapse under the weight of epiphytes.
Plants have thick, waxy leaves with pointed tips. The pointed tips (called drip-tips) channel the water to a point, so it runs off – that way the weight of the water doesn’t damage the plant, and there’s no standing water for fungi and bacteria to grow in. The waxy coating of the leaves also helps repel the rain.
Leaf stems are also flexible to allow leaves to move with the sun to maximise photosynthesis.
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