Winter Colour in trees

We have a variety of grey coloured deciduous trees and shrubs in our winter, and these form a background to our landscape, but evergreens and other trees provide highlights in our yards and boulevards. Part of the planning process for the upcoming growing season could be to see how to add colour to our winter views. Bright coloured dogwood for instance can bring raise one’s spirits if certain varieties are chosen: the two often used are the red or scarlet stemmed dogwood, or the greenish-yellow dogwood: no matter which type you choose, the brightest colour comes from the young twigs, rather than the grey and scarred old stems – prune them off.
Tree bark similarly provides most colour from the younger branches. Older varieties bear the scars of life, but this appearance is not all bad news: the corrugations in the bark provide refuge for “bugs”, both good and bad, and therefore provide a smorgasbord for over-wintering birds. As an aside, I recently read that many birds that are fed at bird-feeders will survive even if their bird-feeding tables are without seeds … and I see that smaller birds flock to shelled black-oil sunflower seeds but eschew many of the mixed grains including red milo that is cheaper … probably only pigeons will eat milo. Another advantage of shelled sunflower is that there is no debris to cleanup in the spring.
In Calgary, trees with fabulously coloured bark include mountain ash, amur cherry, birch, and Japanese tree lilac. Unfortunately the first two suffer from winter sunscald often on the south or south-west side of their trunk. The lentil-shaped marks (usually horizontal, and very visible on white-barked birches) on tree bark are lenticels. Apart from being attractive decorations, more critically, they provide for gas exchange between the atmosphere and the inner tissue, essential to the health of the tree. They form by extrusions from the cork layer of the tree stem and these protrusions often grow larger with increasing circumference of the stem. Check out your neighbours’ trees!
Glynn Wright, January 17th, 2016