Trees’ point of view
But what about those trade offs between epiphytes and the trees they grow on? we’ve seen the advantages the tree offers the epiphytes – a good berth in life, a sundrenched platform. But what do the epiphytes offer the tree?
Much less. They may contribute nutrients: sometimes the tree will produce roots that grow through the air, high up, and reach into the litter in which the epiphyte is growing.
But in general piphytes are a disadvantage from a tree’s point of view. AS rain falls through the canopy, epiphytes remove from it nutrients that the tree could have used. Moreover, small epiphytes like mosses and lichens cut down the amount of light available to the leaves they are growing on. Large epiphytes block out the sun.
And the sheer weight of thousands of piphytes (specially after a rainstorm) is a tremendous load for a tree. To hold up this burden, a tree must use its resources to grow thicker. If it isn’t massive enough, it will be torn down by the extra weight.
So the trees fight back, in this struggle for survival. They grow leaves whose shape and surface texture help them to shed water fast. They produce smooth bark for the same purpose. Some even shed their bark off in flakes to get rid of piphytes. And some trees have bark that contains chemicals that keep lichen and algae from growing.