To understand the forest, we first need to know about trees. Trees are familiar elements of our landscapes.

They are living things and, like all other living things, they are born, grow, reproduce and die.

A 300-year-old yellow birch!

What is a tree?

The dictionary defines a tree as a large ligneous plant with roots and a stem, known as a trunk, which bears branches. Generally speaking, trees are over 4 metres high. A plant that is smaller and has numerous branches growing from its base is known as a shrub or bush.

Trees can be divided into two main categories, namely the conifers, also known as softwoods, and the hardwoods.

Conifers
(Gymnospermae)

The leaves of conifers usually take the form of needles or scales. Conifers produce cones, hence their name. Cones are the fruit of the tree, and contain seeds. The wood of conifer trees – the balsam fir, for example – contains a fragrant gum-like substance known as resin. Their name in French (“résineux”) is derived from this trait.

Québec is home to approximately 20 softwood species.

Black spruce		White pine		Tamarack

Hardwoods
(Angiospermae)

The hardwoods are sometimes known as deciduous trees. Because of their physical and chemical properties, their wood is usually denser and hence harder than that of the softwoods.

In our temperate climate, the hardwoods lose their leaves in the fall. The fall colours offer a wonderful visual spectacle. Québec is home to more than 50 hardwood species.

Yellow birch		Trembling aspen		Beech

Tree reproduction

Hardwood and softwood trees develop reproductive organs when they reach maturity.

In softwood trees, the seeds are contained in an organ known as a cone. Cones are produced by pollination (fertilization) of the female flower. The pollen from the male flower comes into contact with the female flower through the combined action of insects and wind.

Male balsam fir flower		Female balsam fir flower, which will become a cone after pollination		Balsam fir cone; itsseeds will be scatteredand will germinate onthe ground

In hardwood trees, the organ containing the seeds is known as the fruit. A fruit is produced through pollination of the female flower by pollen from the male flower.

Reproductive age varies by species. For example, the white spruce and arborvitae begin producing seeds at between 20 and 30 years of age, the black spruce and white birch at around 15 years of age and the red oak at around 20 years of age.Québec’s emblem tree, the yellow birch, begins producing seeds at around 40 years of age.

The seeds of hardwood and softwood trees are transported by wind, water or animals. If conditions are favourable, they will germinate to give birth to new trees.

Tree growth

Trees grow both upwards and outwards.

Upward growth takes place through the end buds located at the end of the branches.

Outward growth is derived from a layer of cells known as the cambium layer located beneath the bark. During each growth period, the cambium forms a new outer layer of cells that is larger and paler in the spring, and smaller and darker in late summer. The age of a tree can be calculated by counting the number of pale and dark layers, known as growth rings. This outward growth explains why a spile – a small metal spout or tube inserted into a sugar maple tree to gather the sap during the spring thaw– that is left in place for a long period of time will remain at the same height on the tree, but will be completely enclosed in its trunk.

The annual timber volume growth of a tree can be calculated by measuring its diameter at regular intervals.

Some species grow more than others, or faster than others. These are genetic traits. However, numerous other factors influence growth quality and quantity, including temperature, rainfall, soil quality, light quality, competing vegetation, insects and diseases. The growth rings reflect the conditions in which the tree has grown.

The age of a tree can be established without chopping it down! A cylindrical sample known as an increment core is removed from the trunk using a device known as a Pressler borer, and the growth rings on the sample are counted. The drill hole will heal over time.

		A forester removes a sample using a Pressler borer and counts the growth rings.
		An increment core
An ash cross-cut showing the growth rings.

From tree to forest

A large tract of land covered by trees is known as a forest. There are many different types of forests, which are named after the dominant tree species – for example, a maple forest, a spruce forest or a fir forest.

Foresters use their extensive knowledge of trees to establish the best way of harvesting them and protecting their natural regeneration.

Very young maple trees normally grow in the shade of other trees, so foresters will apply partial cutting techniques in maple forests to avoid leaving too much light after logging. Young yellow birch and oak trees do best with a little more light, however, so foresters will encourage regeneration of these species by creating small openings in the forest canopy.

Spruce and fir trees prefer full light. The best type of cut in these forests would therefore be to remove all trees with a diameter of more than 10 centimetres in a given sector. This creates conditions conducive to germination and growth.

A world of its own

Forests contain more than just trees. Québec’s forests provide shelter for more than 400 species of mammals, birds, reptiles and amphibians, thousands of insects and thousands of other plant species. All these living organisms depend on different forest environments for their survival. Today, the forest industry protects forest biodiversity by practising a form of silviculture – the cultivation and harvesting of trees – that is respectful of natural habitats.