Trapping snow could also be a reason for leaf retention. This would allow for more moisture on the forest floor during the spring when the tree is coming out of dormancy.
Another possibility for marcescence is to protect the tree from browsing animals. These dry leaves may be protecting buds. Since dry leaves are less nutritious than green leaves an animal is less likely to remove the brown leaf to gain access to the new buds that are formed underneath. This would be especially important to small trees.
These are just a few possibilities of why marcescence happens. We don’t know whether this provides a competitive advantage or if it is just a coincidence. But what we do know is that these leaves stay on until spring when new growth starts and the buds expand, pushing off the old leaf. This can make for a long noisy winter of rustling leaves in the wind if you have and oak or beech near your home. I hope this article shed some light on why some deciduous trees retain their leaves and others don’t.