What changes on the forest floor when a tree falls?

Have you ever walked in a forest and stepped over a big log lying on the ground? Imagine running your hand along its bark, rough and cool and a little damp. That log was once a tall tree, standing up straight among the others.

Under all those standing trees, the ground stays cool and shady. Ferns and moss grow quietly there, out of the wind. So what changes down on the forest floor when a big tree falls?

High above the forest floor, the treetops spread their leaves and branches side by side. Together they make the canopy, which means the roof of leaves over the whole forest. The canopy catches most of the sunlight, so only small spots of light reach the ground.

When a big tree crashes down, it pulls its own piece of the canopy down with it. Now there is a hole in that leafy roof, right where the tree used to stand. From the ground, you can look straight up through it and see open sky.

Bright sunlight pours through the hole and lands on the forest floor. That patch of ground turns warm and bright for the first time in many years. Tiny plants have been waiting there in the shade. What do you think they will do now?

They grow! These little plants are seedlings, which means young trees that have grown from seeds but are still very small. Plants use sunlight to make their food, so with all this new light the seedlings start to grow fast.

All the seedlings in the sunny patch race upward, each one stretching toward the hole in the canopy. Soon the bright patch on the forest floor is crowded with young green trees.

Meanwhile, the fallen tree lies on the ground, and it is changing too. Beetles chew tunnels under its bark, and mushrooms grow on its damp wood. They are eating the wood, slowly breaking it into softer and softer bits.

As the log gets soft, it turns into a home as well. Snails, worms and salamanders creep into its cool, damp cracks. There they can hide from hungry birds and keep their skin wet.

After many years, the log rots so much that it crumbles into soft brown bits. That soft wood mixes into the ground and becomes rich soil, full of good things plants need to grow. The young trees nearby soak up those good things through their roots.

Canopy and seedlings. When a tree falls, it leaves a hole in the canopy, so sunlight reaches the ground and seedlings grow fast, while beetles and mushrooms turn the log into a home and new soil.

Next time you see a fallen log, you can say a quiet hello to the new little forest growing all around it.