Leaf litter is the thick layer of leaves that builds up on the forest floor as a result of leaves dying and falling off. It is particularly noticeable in the autumn/fall each year in forests of broadleaved deciduous trees such as oak and beech.

Leaf litter is a vital part of the world. The leaves contain nourishment that was taken out of the soil by plant roots as the plants grew. Now it has to be returned to the soil so that other plants can grow, and so the soil can keep its fertility.

Have you ever wondered why leaves don't seem to pile up on the forest floor year after year. Where do the leaves go?

When leaves fall to the ground they are hard and brittle. Over the following months rain will fall, the leaves will soak some of it up, and they will go softer. Animals will come up from the soil and begin to eat these soft leaves. Earthworms are especially important. Microbes will also get to work on the soft leaves, gradually breaking them down into liquids. Those liquids then get carried into the soil by rainwater. The liquids contain the nutrients living plants need, so the rainwater is actually a liquid fertiliser as it enters the soil carrying the liquids from decaying plants.

Gardeners and farmers also make leaf litter fertiliser. They call it compost. They make the natural decaying action faster by piling the dead plant material up into bins so that the heat released as the microbes get to work cannot escape. The warm compost decomposes even faster and more completely than if it were on the forest floor. Then farmers and gardeners spread it over the soil, along with the worms and microbes that have made it their home.