I live in Calgary Alberta. Two years ago I bought a white birch from a nursery. It was about 12 feet high and the trunk was 10″ in circumference at the base. I dug a hole about ^” shallower than it should have been, and added about 1 foot of topsoil around the root ball, and built up a retaining wall 6″ high and 4 feet in diameter around the tree to bring the soil level up to the top of the root ball. When I bought the tree it had small leaves, like a cutleaf birch, I planted it in summer. Next year the tree had leaves about 1/2 way up it’s trunk. The same this year although the trunk has grown to 15″ circumference at the base. Will the leader recover or should I replace the tree? Soil is about 1 foot topsoil and heavy clay below that. Tree is on the north side of the house. I have a thriving weeping birch on the south side of the house about 40 feet high.
I am curious as to why you chose to plant this tree in a tree well rather than in ground. It is possible that the tree was weakened from lack of water (or too much) in the year of planting and that when roots were damaged by freezing during the winter, the tree couldn’t overcome the damage. Also, birch trees are brittle and are easily damaged by ice and wind.
Birch trees also prefer cool, moist soil. They have shallow root systems and are very sensitive to even short periods of drought or heating of the soil … which might be as much an issue as freezing with that tree well planting system.
You mentioned that the tree is on the north side of the house. If it is in shade, then that may be the problem. White birches are shade intolerant, i.e. they require sunlight on their leaves. If shade is the issue, you must relocate the tree.
You do not mention whether you see any insect activity or indicators of disease, so without physical examination, it is difficult to accurately diagnose the problem. The most common pest is the bronze birch borer, indicators of which are D-shaped exit holes on the branches or stems, just below the dead area. Borers are almost always secondary pests, attacking trees that are stressed, such as by the other factors I have described. Here is a link to a good guide to pests and diseases of birch trees, which may help you to diagnose the issue. Click here.
In any case, even if the tree is relocated, if the top of the leader is dead or profoundly damaged, as it seems, it is possible to prune it out and hope that a side branch will take over as a new leader, or the tree may send up a new shoot from the main stem.
I would strongly recommend you seek the services of a certified arborist. Here is a link to the Prairie Chapter of the International Society of Arboriculture, which provides lists of certified arborists in Alberta.
Good luck; I hope your tree can be saved!