The trees that drop all their fruit at once are found in Borneo, Sumatra and peninsular Malaysia. A study in Gunung Palung national park found that there aren't enough seeds left for trees to reproduce. Dipterocarp trees, some which grow more than 120 feet tall, dominate the canopy of many Southeast Asian tropical forests. Some of the seeds, illipe nuts, are an important cash crop for locals because of their export value. So the researchers also used seed exports records from 1969 to 1999 to help sort the trees' fruiting pattern.
Flower petals coat the forest floor.
No matter whether the tree flowered early or late, it drops its winged fruit sometime in February or March. In addition to the dipterocarps, other types of forest trees join in by producing particularly heavy fruit. As soon as the dipterocarp trees start dropping the fruits, the animals move in. Leaf monkeys, orangutans, long-tailed parakeets, squirrels, wild boar, jungle fowl, emerald doves and several species of rodents forage through the forest, gorging themselves. Even so, some seeds escape and germinate, carpeting the forest floor with tiny green seedlings.