Lesson One - Values of Forests


Knowing the species, size and maturity of your trees is essential to good harvest decision-making

Owning and managing woodland is a long-term endeavour. Like humans, trees can take decades to mature, and not all trees on your woodland may be growing at the same rate, nor are they all at the same stages of maturity. Some species, like red spruce, Nova Scotia’s provincial tree, does not mature until it is nearly half a century old. If you ever intend to harvest timber, it is important that you know the species and maturity of your trees. A tree is considered mature when it is old enough to produce healthy seed, and when its annual growth is beginning to decline. Some trees, like red spruce, eastern hemlock, sugar maple and yellow birch, may remain mature for more than a century before their growth begins to slow. Even when they are overmature, trees can still be valuable. They can provide important wildlife habitat for birds and mammals that require large-diameter trees for nests and dens. Often, hollow areas develop at the base of such trees, creating shelter for mammals such as red fox and even black bear.

A snag and cavity tree

 

Cavities may also be present in areas of the tree high above the ground. These cavities are usually created by primary excavators – such as woodpeckers – that are searching  for insects beneath the bark of the tree. These small cavities are important habitat for birds like black-capped chickadees.

As the wood begins to rot the cavity becomes larger and can host northern (and southern) flying squirrels, red squirrels, bats and even voles and mice that venture into a tree’s upper reaches. Overmature trees have values that are not easily quantified in financial terms.

Trees play an important role in the storage of carbon. As they grow, trees absorb carbon from the air and soil, accumulating it in their stems, branches and twigs. By storing carbon, trees help slow climate change.

A curious northern flying squirrel

 

Forest Soils

The soils beneath a stand of mature and overmature trees are teeming with life. Trees are important in contributing  biodiversity to forest soils. Tiny strands of fungi, called mycorrhizea, form dense networks in the soils beneath mature and overmature forests. Mycorrhizae link rootlets of trees with moisture and nutrients that would be otherwise inaccessible.

Many other types of fungi thrive in the forest soils and decaying  wood of mature  and overmature trees. These include the hyphae of mushrooms such as chanterelles and honey mushrooms, which are edible. A type of fungi called chaga grows on the trunks of birch trees, and can be used for making a tasty tea.
 

Mushrooms are evidence of complex life beneath the forest soil.

 

Soils rich with fungal strands are important to wildlife species that require such concentrated masses of mycorrhizae  for food. Examples include flying squirrels, red-backed voles and blue-spotted salamanders that rely on a nutritious moist environment  for food.

Mycorrhiza is an important driver in the cycling of forest soils.

 

Why Harvest?

Harvesting your woodland is an important decision which should be based on the condition of your forest stands.

Timber harvesting can be undertaken  for a variety of reasons, including:

Not all trees that are cut need to be large diameter. Markets exist for small-dimension timber that can provide a good return.

Scaling firewood  for sale

A harvesting operation must, at a minimum, include the following:

The terms “logging” and “harvesting” are often used interchangeably. Both refer to the process of felling, processing and extracting the timber to a site where it is accessible to trucking.

 

Trucking is an essential of every harvesting operation

 

 

 

 

 

 

 

 

For successful timber harvesting  to occur, a number of factors must be considered. Think of moving several hundred (or thousand)  tonnes of heavy, bulky trees over rough ground, then transporting them to a mill perhaps hundreds of kilometers away. You must do this while protecting the integrity of the forest ecosystem, including  the soil, watercourses, standing trees and existing seedlings and other plants. This task obviously cannot be taken lightly!

Disease or insect outbreaks  may hasten harvesting  decisions, such as in this stand of white  spruce killed by bark beetle

Once a stand is overmature or infested with insects or infected with disease, there may be few alternatives to harvesting, other than letting the dynamics of the stand run its natural course.

Wildlife Considerations during Harvesting

When large, overmature trees die, they become valuable habitat for many species of wildlife. As discussed in Module 4, the trees that offer the most benefit to wildlife are large-diameter, shade-tolerant hardwoods such as sugar maple, yellow birch and red oak. Due to damage  caused by wind, lightning strikes and resulting rot, these trees can have large hollows that make ideal nests and dens for a variety of species. These trees may live for centuries, providing steady shelter for large and medium-size mammals and birds.

Some trees create good wildlife  habitat

Large trees also provide good platforms for stick nests. Hawks, owls and eagles usually require large trees in which they can build their nests. You may find a barred owl nest in a yellow birch tree that has a wide, spreading crown. If you have white pine trees that are standing head-and-shoulders above all the other trees on your woodland (these are called supercanopy trees), bald eagles may have built a stick nest in one or more of them.

Knowing your woodland and the kinds of wildlife habitat that use it can help you make good decisions when you wish to harvest timber. Spending some time walking your woodland looking for signs of wildlife is time well spent. Don’t forget to look up: stick nests are easy to overlook. Pay attention to trees that have died and are still standing (snags), since cavities can hold the nests of saw-whet owls, American kestrels and other small predatory birds.


A forest raptor  that  requires undisturbed areas of large trees for nesting is the northern goshawk. Although uncommon, goshawks have territories that can include both dense cover and open woodland.


Northern goshawk. Photo courtesy of NSDNR

 

Planning Your Harvest

We’ve all heard the saying, “Measure twice, cut once.” And once a tree is cut, there is no way of putting it back! For that reason, it’s important to have a clear and thorough plan in place.

Some of the questions that need to be answered when planning your harvest include:

 

Plan your work, work your plan

 

Timing Your Harvest

Many birds such as hawks and owls begin breeding and building their nests in early spring, so it is important to avoid disturbing them at this time of year. Once eggs are laid, birds are very prone to even small disturbances and will leave their nests if the disturbance is prolonged.

If you are planning a harvest during a given year, both the stand that is considered for harvest and the area around it should be thoroughly inspected for stick nests and large cavity trees. If it appears that they are in use by hawks, owls or eagles, buffer zones should be established with flagging  tape and every effort should be made to avoid disturbing  the birds. Any sizable  stick nest should  be reported to your Regional NSDNR Wildlife Biologist.

During the active nesting months of May and June, it may be prudent to avoid working in the area altogether, since the noise of chainsaws or heavy equipment can persuade raptors to leave their nests and young.

It is good to keep tabs on what is happening on your woodland at all times of the year – even in winter. Areas of thick conifer (softwood) cover are frequently used by whitetail deer during winters of heavy snow. These sites are called deer wintering areas and can be several hectares in size. Within these stands the snow is less deep and the air temperature a little warmer than surrounding areas, making a difference in survival for deer that tend to congregate here. If a deer wintering area is slated for harvesting, ensure that there is an alternate area nearby in which deer can take refuge during winters of heavy snow.

During winter, whitetail deer forage for food in open fields, but prefer to shelter in thick cover.

Considering the seasonal conditions of your forest soils can help you avoid problems with soil compaction and rutting caused by heavy equipment. During wet seasons, forest soils can be significantly damaged by equipment as light as a farm tractor. Wetter sites may be better left for drier times of the year, or during periods when soils are frozen.

Ponder Regeneration Prior to Harvesting

Before cutting even a single tree, progressive woodland owners consider what will replace it, and how that will occur. It’s important to plan for healthy regeneration in areas that are about to be harvested.

You may wish to ask yourself the following:

 

These are just a few of the many questions that should be answered before a site is harvested.