Think back to the last time you enjoyed a scenic walk in a forest. Maybe you stared up at the blue sky peeking through a canopy of branches, with birds resting high at the top of an old tree. Perhaps there was the sound of a babbling stream rushing nearby the hiking trail, or you witnessed busy squirrels dashing about, collecting food.
If you looked down, you may have noticed a bed of fallen leaves, their earthy aroma rising to meet you with each inhale. You probably looked back up immediately — after all, you came for the view, not to stare at the ground. But what you may not have known is that important things were happening in the leaf litter right under your feet.
When trees shed their leaves, bark, and other organic elements, the debris is deposited onto the forest floor and incorporated into what is known as the soil organic layer. The organic layer also contains animal scat, moss, and small flora and fauna. This is called leaf litter, and it’s an important part of the organic layer of the forest. Its decomposition leads to the transfer of nutrients between the above-ground vegetation and the soil. This layer also provides food and shelter for various bugs, birds, and mammals. The organic layer plays a vital role in maintaining the health of a forest.
As the season's change, so does the frequency and composition of what ends up on the forest floor. Forest climate has an impact on leaf litter characteristics, as decomposition happens faster in hot, humid temperatures than in cooler ones. The hibernation patterns of the forest creatures vary with the climate, so you may find different critters burrowing under or taking food from the leaf litter depending on the time of year.
Why is leaf litter important?
If you see leaf litter in your own yard, you may be tempted to rake and bag it. While it may look messy, the organic layer matter is important in maintaining the forest’s ecosystem and biodiversity. Here are ways leaf litter helps a forest thrive:
- It feeds the plants. Leaf litter is broken down by environmental weathering and decomposers like invertebrates, fungi, algae, and bacteria. These organisms recycle the litter into nutrients that are spread throughout the forest and absorbed by plants, helping new growth flourish and thrive. Think of it as slow-acting fertilizer. During this process, fungal spores and seeds are also distributed across the forest floor.
- It feeds the forest inhabitants. The tiny organisms that live in the leaf litter play an important part in the forest’s food chain, often becoming food for larger creatures. This activity on the forest floor affects productivity at other levels. For instance, the more insects that are on the ground, the more food there is for squirrels. More food for squirrels means more food for raptors, and so on.
- It protects the soil, roots, and seeds. Organic matter protects the ground from heavy rains, shielding the soil from erosion. Leaf litter also helps soil retain moisture, and provides it with nutrients as it’s broken down. In cold weather, leaf litter acts as a blanket to protect root tips, seeds, and small plants from the temperature.
- It provides a home. Leaf litter is not only home to the invertebrates that help it decompose, but also provides shelter and coverage to a variety of forest creatures.
Leaf litter is home to the decomposers who do the work of breaking down the organic materials into nutrients. Soil inhabitants include worms, fungi, insects, and other microbes. The composition changes with the seasons, and at times may provide a cozy habitat for snakes, amphibians, and small mammals. Birds may swoop down and take some litter to add to their nests (and find a tasty snack while they’re at it.)
Get to know the leaf litter in one of our memorial forests — just be sure to look up from time to time!