Last weekend at Belt Woods, I walked thru a section of the reserve that was clear-cut several years ago. The forest has since been regenerating, but the appearance of the forest was so different than that of the old-growth section where the trees are believed to have never been cut that I decided to post pictures here.
The first picture shows the regenerating 2nd growth forest.
Here, all of the trees are young, have narrow trunks and their stands are dense. On the ground there is very little deadwood; what is there consists mostly of small branches. Because the canopy formed by the young trees is not very extensive, plenty of sunlight reaches the ground.
Compare this with the below photo of a typical scene from the old-growth forest.
The old-growth forest (and in general, any old enough 2nd growth forest) is characterized by huge trees (in addition to younger ones) that are more widely spaced as well as a large amount of rotting wood on the ground. Also when the canopy is fully developed, especially in the summer before the leaves start to fall off, very little sunlight gets thru to the ground.
One additional and important characteristic of old forests is the thick layer of litter or humus consisting of rotting leaves and wood and other plant parts mixed with animal remains that covers the ground. This litter layer provides habitats and food for many small animals and fungi. Young forests growing on heavily disturbed soil, such as an abandoned farm field, lack this litter layer and it may take many years before enough of it accumulates.