It's hard for temperate folks to appreciate just how incredibly agressive tropical vegetation growth can be. I'm only subtropical but I've got a tree that's about 6 years old and a foot in diameter. And that's after I've topped it at 5 ft(0 branches left, just a stump) every 6 months or so just to try to keep it under control. If I'd let it run rampant it would be at full growth now, around 50ft and 1.5ft across. I had another tree that went from 10 inch seedling to 10ft and bearing fruit in 9 months. A field abandoned for 30 years in the amazon is 100% jungle.