TROPICAL RAIN FOREST

Indicator Plant Species

While it's hard to pick indicator plant species there is something that many of the tropical plants share.  That is a drip tip on the ends of the leaves (below).  This pointed tip promotes drainage from the surface of the leaf, and thus helps keep the leaf surface clean of epiphytes and fungi in the humid forest. 

One of the biggest challenges in biology is explaining the diversity of the rainforests.  Certainly the high productivity permitted by the ready availability of water combined with the warm temperatures is a factor.  The massive size of many of the trees provides a number of new habitats for animals to exploit. The extreme specialization to avoid competition is another factor.  Some scientists propose that human interference, in the guise of clearing small areas for agriculture, may play a key role as well.  And there is time; the rainforests are areas which have been relatively unaffected by the climactic shifts associated with the  glaciation which ended about 10,000 years ago. Which of these factors is most important?  Do all of them play a role? These are questions scientists are still grappling with.