What are the effects on the ecoysystem from the common fig tree.

I think you are starting from an incorrect premise:

"Figs are one of the most important plant species of a rainforest
ecosystem
... Figs are considered a "keystone" species because they are so
important to the animals of the rainforest. This is so because figs
bear fruit several times a year. Different species of figs fruit at
different times so that there is always a supply of food for animals
that depend on fruit as a major part of their diet. A large variety of
herbivores and omnivores eat figs. In some forests up to 70% of its
animal's diets depend on figs"
http://www.blueplanetbiomes.org/strangler_figs.htm

Tehuti is correct...a fig tree in it's place is a wondrous thing.

However, a fig tree out of place can be a real pain in the you know
what.  Fig trees are included among the types of pesky aliens known as
"invasive species".

When introduced into an ecosystem where they have not, naturally,
grown, they can grow aggressively and rapidly, and in the absence of
natural enemies, will thrive to the detriment of native species.

I'm sure a search on "fig tree" and "invasive species" will turn up
some useful information for whoever is so inclined.

pafalafa-ga