As well as all the trees and flowering plants mentioned in the Tropical Biodiversity section, rainforest composition also includes abundant climbing plants like orchids, ferns and the dominant climbers known as woody vines or lianas. These woody vines are rooted in the ground and grow around tall rainforest trees. Lianas can reach over 200 metres in length. Due to the thin layer of soil in rainforests, vines provide important support for tall trees. This all changes when a heavy tree falls, however, as the network of vines will also pull down some of the surrounding forest. If a sufficient amount of vines have collected around a dying tree, the vines can support the tree while it decomposes. This process leaves behind an interesting casing of vines that continues to grow despite the tree’s death.
Epiphytic plants also provide a notable rainforest composition component. These grow on the trunks, branches, and the vines wrapping around rainforest trees. The word epiphyte is from the Greek word “epi” for upon and “phyte” derived from the word for plant. These non-parasitic plants don’t harm their hosts, as they get their moisture and nutrients from rain and the humid rainforest air. The epiphytes grow on trees as few can tolerate the low light-level on the ground, most living in the high light-levels of the rainforest canopy.
Low Light Levels
Less than 10% of light makes its way through the canopy, which is why vegetation below the canopy is sparse. But when a gap opens in the canopy by a disturbance, a shaft of light hits the floor that stimulates growth of isolated herbaceous plants. A thick layer of undergrowth only occurs during the first stages of regeneration when trees fall because of wind or human activity.