By Hans van Veluwen

There are several species of Fig Trees ( Ficus sp.) that are referred to as "Strangler Figs" growing throughout our Tropical rainforests.  However, it is a deceiving term, because the tree does not actually strangle off its host tree at all.

When a Fig seed lands or is deposited by a bird or other animal into a large Epiphytic fern, like an Elkhorn clump or a Basket Fern and the conditions are right the fig seed will germinate. The seedling Fig uses the moisture and nutrients meant for the fern to live on while it puts a thin wire like root down its host tree.

Eventually when that root reaches the ground it starts to absorb nutrients by itself and the roots will begin to swell and eventually throw out lateral  roots which will encompass its host tree.  It uses the host tree for support. The advantage the Fig tree has in growing this way is that it starts its life high up in the canopy of the tree where all the sunlight is.  

In other words it doesn't have to compete with the hundreds of seedlings that start their life on the forest floor, it simply starts its life in the canopy of the forest and works its way down. When the host tree dies and the fig tree is strong enough to support itself the host tree will simply rot away from within, leaving a hollow like structure.  If the Fig tree is not strong enough to support itself when the host tree dies then both trees will simply fall to the forest floor.

Sometimes on it's way down the Fig tree will land against another tree and if the Fig tree survives will quickly throw down adventitious or aerial roots in an attempt to stabilise itself, that's what happened to the famous Curtain Fig Tree in the Atherton Tablelands.

Most trees you will see growing around you in tropical rainforest will only live to be two to three hundred years of age.  Fig trees can live to be seven hundred years old so they simply out live the host tree giving people the impression that it's killed it off.

It's not in the Fig Trees best interest to kill off the very tree that's holding it up. Sure, it will compete for light and nutrients with its host tree but so do all the other trees directly around it because although it looks very lush and green in this Tropical Rainforest, what we are dealing with is a very short nitrogen cycle. More on this next week.  For more rainforest info visit www.c3d.net.au