Vines most successfully compete for sunlight in tropical rain-forests by _______.
A) climbing up into the canopy
B) strangling the trees they grow on
C) having broader leaves that absorb more light
D) having thick, woody stems
B) They strangle the trees they grow on
In the tropical rain forest, the highest layer consists of the tallest trees, about 150 feet or more, which form a very dense leaf canopy. The sunlight is blocked by the canopy and left the lower plants without sunlight. Vines are grape family that is trailing woody. They have capability to get the sunlight by strangling the trees they grow, crawling, in order to reach the canopy of the trees. Once they reach the canopy, they can get their share of sunlight.
Light level must increase if we rise into the upper layers. One strategy to survive in a rain-forest is having a rapid vertical growth so that we can find abundance sunlight. Liana, a well-known type of vine tree, is a general term of woody vine that live in rain-forest. Lianas use the strategy of rapid vertical growth to survive. Liana’s growth rate is of up to 2′ to 3′ per day. Once they reach the upper canopy, they can command their share of the sunlight.
Vertical grow strategy is also used by rain-forest trees. They grow vertical and straight. Their lower trunks have few or no branches. Meanwhile, sapling trees have to wait until there will be a gap in the canopy opens up. It might because of a fallen tree. When the sunlight can get down to the lower level, the sapling grows more rapidly to reach the canopy level.
Therefore, vines are very lucky that they have capability to strangle the trees they grow so that they can crawl and reach the top of canopy.
Photo credit: wikimedia.org/wikipedia/commons/thumb/e/ef/Lianas%2C_Udawattakele.jpg/800px-Lianas%2C_Udawattakele.jpg