Picture showing
the multiples species of plants found
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the forest is evergreen throughout the year as trees do not shed their leaves at the same time. Due to climate associated with the forest, there is no climatic reason for the trees to shed their leaves. They grow throughout the year. The leaves are usually broad and dark green. This is to maximise the capturing of sunlight for photosynthesis. They are also thick and leathery to withstand the excessive heat. The leaves are smooth and have drip tips that allows excess water to slide off. The bark is smooth and thin as there is no necessity for protection against cold or dry weather. The branched and their leaves are found at the top one-third of the trees to obtain the maximum amount of sunlight. The roots are shallow as the nutrients in the tropical rainforest are found at the top soil. Many trees have buttress roots that can be 3m above the ground for supporting the tall trunks. The trees do not grow in pure stands. It is common to find 100 species of trees in 1 hectare of land. Due to the continuous canopy, sunlight cannot get to the forest floor, thus the undergrowth is sparse. Light is undoubtedly an important element in the growth of plants. However at the forest floor, due the thick canopy above, light cannot penetrate through into the heart of the forest. But this is exactly where the young saplings starts from. How then do they grow to attain amazing heights? To solve this problem, some species of trees develop large seeds that contain enough food reserves to allow the seedlings attain a height of 1metres or more. For those with small seeds, they rely on high light to germinate and grow. Some seeds also can lay dormant for many years before they start to germinate. For example, the yellow walnut found in Queensland, can be dormant for up to 11 years. Once in the sapling stage, they need more sunlight to grow to higher heights. Many species has the ability to wait for a gap of sunlight to reach them for years without growing. Other trees can however grow even though slow, through the capturing sun flecks that cross the forest floor, using special pigments.
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