The plants and animals of each forest occur in unique combinations. Here are some thoughts on what influences species distributions and species composition in tropical rain forests. The species composition of a forest, or of part of a forest, may have been influenced by climate changes that occurred thousands of years ago. The current composition of a rain forest may, in part, be the result of which plants and animals happened to be available when the forest was expanding at some time in the past. Forest gaps are created when a tree falls due to old age or perhaps when several trees fall during a large storm.
Gaps create places where lots of light can reach the forest floor.
The plants that colonize a gap are near enough for their seeds to reach it and are able to grow in high light conditions. As time passes, trees growing in forest openings create shade in which other, shade-loving, species can thrive. Regeneration of forest gaps adds to the complexity of rain forest species composition and distribution. They each will be in different stages of regeneration. Climate Rain forests of the world grow in similar climates.