Fallen tree leaves on the forest floor are called leaf litter. Although scientists can examine leaf litter on the surface of soil by collecting it using litter traps, studying what is happening underground is much more difficult. Decomposing in a comparable way to leaf litter, root litter refers to shed tree roots that have aged and died. Investigating root litter is tough, but it is especially challenging to study the litter of fine roots, those roots 2 mm or less in diameter, which control the uptake of nutrients and water by trees.
