The forest Floor
A forest is a place of immense biological activity in the soil. Leaves falling to the forest floor are broken down and incorporated into the organic content of the soil. Leaves from deciduous trees (such as Oak) decompose faster than evergreen leaves (such as pine needles). If you are walking in woodland in Winter and are unsure of the tree species, an inspection of the leaf litter quickly reveals the type of fallen leaves and thus the tree species. The examples below shows the forest floor from three quite distinctive forest types, and the resultant leaf litter collecting beneath the trees. It is interesting to compare between them.The first picture is taken in a dense Oak (Quercus) woodland. Load the full size image of the Oakwood floor and see how many different type of plant items are visible. Look for the new sapling growing up, as well as old leaves rotting down to form organic matter.
Now compare the image of the Oak woodland floor with this image of the woodland floor of the Sweet Chestnut (Castanea sativa). How do they compare?
Finally, compare the images above with this image of a coniferous woodland floor. Can you see the young sapling, and the bracken leaves. How do all these images compare?
How long do you think the leaves in these images will take to become soil?
Did you know that deciduous, or 'broadleaved', tree leaves such as Oak and Beech will rot down and become soil over a period of roughly 2 years. That is quite a long time - but pine needles dropping in a coniferous woodland can take much longer - perhaps 5 years to completely rot down! The amount of final soil coming from one leaf would be very small indeed though. You can see how it can take up to 500 years for a centimetre of soil to form.