Forest thinning could serve multiple purposes in N.W.T.'s battle with climate change

Our planet is changing. So is our journalism. This story is the first in a series, by CBC North, that examines carbon storage with the N.W.T.'s natural environment. It's also part of a CBC News initiative entitled Our Changing Planet to show and explain the effects of climate change and what is being done about it.

Just south of the N.W.T. border, a crew of six from Smith's Landing First Nation are cutting down trees, hauling them out of the forest, and setting fire to piles of pruned brush. 

The strategy is called forest thinning, and the community received funding from the Forest Resources Improvement Association of Alberta to use it on 7 hectares of forested land in Fort Fitzgerald, according to Becky Kostka, the First Nation's lands and resources manager. 

She said the area was prioritized for the association's FireSmart program because of the density of fast-burning spruce trees in the area, and their proximity to peoples' homes. 

Since late October, she said crew members have been cutting down trees so their crowns are three metres apart, pruning trees up to six metres, and clearing away ladder fuels — which are highly flammable vegetation, living or dead, that would allow fire to climb from the forest floor and into the tree canopy and to become more intense. 

The goal is to create space within the forest that would slow down a massive fire, she said. 

"Before, if you would stand in Fitzgerald and look to the forest, you couldn't see through the forest," said Kostka. "Now, slowly, as the crew is working, you can see further and further through the forest." 

Forest thinning has parallels with low-intensity burns — known as cultural burns — which were lit purposefully by Indigenous people around the globe to rebalance ecosystems. 

"Traditional knowledge tells us that actually burning in places helps us suppress forest fires in the long run," said Kostka. 

A tool with a dual purpose

In Fort Fitzgerald, forest thinning is being used as a tool for adapting to the impact of wildfires, which are becoming more frequent and more severe as a result of the world's changing climate. It's called "vegetation management" in the N.W.T., and it's being used with the same purpose in places like Hay River, Enterprise, Fort Liard and Fort Good Hope. 

But the territory is also testing it out as a tool that could prevent the climate from changing even more.

Tom Lakusta, manager of forest resources for the N.W.T.'s environment and natural resources department, said the territory thinned 11 hectares of forested land north of Sandy Lake, in the South Slave region, as part of a pilot project this fall.

The hope is the remaining trees will grow bigger and healthier, and will be able to suck twice as much carbon out of the atmosphere over the course of their lifetime.

Lakusta said pine trees have wax-covered cones that require a fire's heat to release their seeds. When a wildfire passes through a pine stand — lots of seeds take root in soil that's been freshly fertilized with ash.

As a result, he said a pine stand can grow much more densely and choke its own growth.

An example of this lies in large swaths of "very short" pine trees east of Hay River, in an area that was hit by wildfire in 1981. Lakusta said the trees are short because they compete with each other, they "don't do a very good job of dying," and they all get fewer nutrients.

The area covered by the pilot project was burned in a wildfire 14 years ago.

Carbon storage 'a new goal'

The environment and natural resources department partnered with members of Deninue Kue First Nation in Fort Resolution to carry out the work between Sept. 13 and Oct. 4, said Lakusta. With funding from the federal government's Low Carbon Economy Leadership Fund, Lakusta said 11 hectares of forested land were thinned to two different densities: 6.8 hectares were thinned 2,000 stems per hectare (sph) and 4.6 hectares were thinned to 4,000 sph. 

An unthinned pine stand in the same burn area could range from 10,000 to 40,000 sph.

Lakusta said by the time the thinned pine stands reach the end of their lives, at 80 or 100-years-old, they will probably have sequestered twice as much carbon than if they hadn't been thinned and their growth was stunted.

Next year, sampling plots will be set up in both thinned and unthinned areas to monitor tree growth and to determine if that goal is reached, he said. 

Between wildfires and natural die-off, trees can sometimes emit more carbon than they absorb. Lakusta said the entire territory sequesters more carbon than it gives off during years when wildfires are light, but when there's a heavy fire year — it becomes a carbon source.

Understanding how much carbon is stored in the natural environment and understanding what risks those stores face, he said, is "kind of a new goal" for forestry management in Canada and the world.