In the northern hemisphere in it is Autumn/Fall.
Just think of woodlands and before humans had lawns, pavements etc that needed to be kept clear of leaves.
Perhaps the original closed loop recycling, is the recycling of the valuable nutrients in leaves, by the tree that shed them.
It is now becoming recognised that the removal of these nutrients (and the grass cuttings from lawns) removes this link and removes nutrients from the tree (lawn).
Also think about when wild flower meadows are created, advice is to remove the nutrients to make the soil poor which encourages (what are viewed as) wild flowers, you are advised to remove the cut grass.
In Hyde Park they recognise that the removal of leaves are inducing a deficiency in nutrients for mature trees and are now feeding trees to replace these lost nutrients (hopefully they will have found a way to use the leaves every year.
At Kew they used to have hundreds of volunteers to clear up leaves. Now they are mulched with mulching mowers where they fall and Tony Kirkham, swears the resulting small sections of leaves are consumed by worms overnight.
The leaves shed by your trees, should be given back to the trees. If you can leave the in situ to compost down, fabulous. If on lawns a mulching mower (one that cuts up grass cuttings so that they are returned to the lawn) will cut the leaves up so small, that the worms will make short work of them and start the recycling.
If these two options are not available, you could compost the leaves down, then in spring gift them back to the tree as a mulch.
Close that loop please!