Q. My neighbor covers the base of his trees with plastic garbage bags. I think it looks ugly but he says it protect the trees from the snow. We are next door and never cover the trees and they are fine. Is he crazy or am I?
A: I'm afraid I cannot determine the condition of your neighbor's mental health, despite the fact that I have a B.S. in Psychology. All I can do is repeat what an old arborist friend once said to me: "Tom, one of us is nuts, and it's not ME!"
Actually, your neighbor may have good reasons for doing this. He may be worried about salt-laden snow getting on the tree, which is valid.
He may be worried about field mice, or other critters like voles or bunny wabbits, hiding beneath a thick layer of snow and chewing off the bark at the base of the trees, which is also valid. I've seen trees (normally young/small diameter trees) completely girdled by mice, and this usually spells doom for the poor tree.
Otherwise, putting plastic garbage bags over a tree's roots is BAD, in appearance and otherwise. Plastic prevents water from getting to the roots - not a good thing. Plastic, especially black plastic, can get the soil beneath it over-heated - also not a good thing.
One way to prevent or reduce critter damage is simply to clean the snow away from the trunks. If the little beggars feel exposed to predators, they won't take a chance sitting around chewing on some tree trunk.
There are also protective "collars" made specifically for the purpose of trying to preclude these little rascals. Put them around the tree trunks in fall, and remove them in spring.
Or, you can wrap the trunks with burlap for the winter (similar to wrapping an injury with an elastic bandage, only burlap isn't elastic). These are more aesthetically-pleasing approaches than using plastic garbage bags.
It is unnecessary to protect roots from clean, unsalted snow. It's snowed for eons and, to my knowledge, this has yet to be a big problem for tree roots.
Snow is actually a very good insulator. Bare soil freezes very quickly (and deep, where many tree roots reside), and snow cover can prevent this from happening, or at least moderate the process. This helps protect roots from having to experience colder temperatures than necessary.
I actually shovel snow ONTO a large rhododendron in front of our house (done carefully, so as not to break branches). The snow helps insulate the plant, protects it from winter's drying winds, and keeps salt spray from getting on and burning the leaves and twigs. I haven't had any of our toothed friends gnawing at its base -- at least not yet.
So, some snow cover can be a good thing!
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