system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: A single tree might shed thousands of seeds a year, but most of these won't grow into anything. What starts the growth of a mighty tree?
gpt
If you look closely, many trees are surrounded by saplings. Most won’t make it to maturity because there isn’t enough sunlight reaching them under the canopy of large trees. Sometimes, an old tree will die, allowing some saplings to grow until they become mighty and take the place of the dead tree. This type of “growth from death” happens in many ways. For example, some pine cones only open up when they get extremely hot during a forest fire. The fire revitalizes the nutrients in the soil and opens up the canopy, allowing light to reach the ground and new trees to grow.