Global warming is changing Canada’s boreal forest and tundra

Climate change will affect Canada’s boreal forest in a complex way. (Shutterstock)

by Konrad Gajewski, L’Université d’Ottawa/University of Ottawa

Global warming is affecting the boreal forest — what happens will depend on the climate, vegetation and the frequency and intensity of wildfires. Changes in the north include increases or decreases in leaf growth, called Arctic greening and browning, more extensive growth of shrubs and treeline movement. It is the interaction of fire, climate and time that determines the nature of the forest-tundra today and how it changes in response to climate variability.

Flammable landscapes and weather fronts

Fires are an important component of the boreal region, burning off old trees and leading to a regeneration of the forest. After a fire, shrubs and deciduous trees grow more quickly and form the canopy, and are eventually replaced by slower-growing spruce. This results in a landscape which is a mosaic of patches, each the size of a fire.

More fires may lead to more of the landscape being in an earlier stage of the post-fire succession growth, including less-flammable shrubs and deciduous trees. At present, the forest is more flammable, as more of the landscape is dominated by spruce, and this is a legacy of the recent past.

a row of trees on a hill
The effects of a recent fire can be seen in the background. (Konrad Gajewski), Author provided

The nature of the forest-tundra depends on variability in the position of the Arctic front and on the fire history of the region, but also its history over the past few millenia.

The Québec forest-tundra

The treeline — the edge of the forest where it meets the tundra — can span from tens to hundreds of kilometres in length. The location of the treeline corresponds to the average position of the Arctic front — a transition between a cold arctic air mass and warmer air.

In northern Québec, the forest-tundra is a broad zone. In the lichen woodland, trees grow throughout the entire landscape. After a fire, trees grow back, as the growing season is long enough to enable seedlings to survive.

To the north, the tops of hills no longer have trees, and the altitude of tundra vegetation becomes lower and lower, gradually covering more of the landscape. Trees still grow on the lower elevations, and typically they reproduce after a fire.

Still further north, tundra covers a larger area of the landscape and spruce are now restricted to growing around lakes or in valleys. Spruce here are typically in krummholz form, with their growth stunted by the cold, windy conditions. Spruce adopts this shrub form when under stress, where the branches remain near the ground with only occasional shoots growing above the snow level.

A small colony of krummholz can maintain itself for centuries in sub-optimal conditions. After a fire, the spruce are killed and there is no reproduction, so over centuries this zone gradually becomes deforested. However, if the climate changes favourably, the trees revert to normal growth and can establish new populations through seeds.

a cluster of spruce growing in a stunted manner
Spruce in krummholz formation in northern Québec. (Konrad Gajewski), Author provided

Climate change history

A long period of cooling or warming makes the zones move south or north. During warm periods, trees grow more to the north, while this doesn’t happen during cold periods.

As the ice sheet that covered nearly all of Canada melted away between 20,000-6,000 years ago, plants migrated north. In the Mackenzie Delta region in the Northwest Territories, the ice retreated relatively early, and trees arrived over 10,000 years ago.

As the ice sheet continued to melt, exposing central Canada, it got cooler in northern Yukon and the Mackenzie Delta area, but warmed in central Canada between 8,000-5,000 years ago. Trees could no longer survive in the northernmost region of the Mackenzie Delta, so the treeline moved south. And in central Canada, trees could now grow further north. Later, as the ice disappeared in Québec, trees migrated into northern Québec. The migration occurred rapidly and changes in the different regions occurred synchronously, but out of phase.

The forest-tundra (treeline) in northern Québec. Upper left: lichen woodland. Upper right: southern tree subzone of the forest-tundra. Lower left: northern shrub subzone of the forest-tundra. Lower right: shrub tundra. (Konrad Gajewski), Author provided

Plant migration and treeline movement

Migration of plants in response to climate changes has two components. A slow migration to the north can occur during warming. Seeds are dispersed away from the parent plant and if the climate conditions are suitable, every generation can establish a little further north. Since the climate is always variable, this occurs in starts and stops.

A second — and more important — mechanism is long-distance migration. The transport of seeds or whole trees down rivers, across the snow or ice, or by birds or animals, enables migration of tens to thousands of kilometres in a very short time. This is what seems to have happened in the past, and this process insures rapid migration to new areas due to the warming climate.

Present-day warming

During the past 4,000 years, there was a long-term cooling — referred to as neoglaciation — which is responsible for the nature of the forest-tundra today. Previously, tree populations were more abundant in the forest tundra of northern Québec. As the climate cooled, the trees reverted to shrub form but no longer reproduced. Fires eliminated some, and since there was no reproduction, the region attained its present-day character.

Now, as the climate is warming, krummholz in place will expand, grow and reproduce. Thus, there is a large area where trees can colonize, suggesting the treeline can move rapidly northward. The long-distance transport of seeds across northern Canada will also enable rapid migration.

However, the relative impact of climate warming and increased fires needs to be accounted for. Thus, present warming of northern Canada will impact the northern vegetation in a complex way, with different regions responding differently, and with some processes occurring rapidly, and others with long time lags.

Konrad Gajewski, Professor, Geography, Environment and Geomatics, L’Université d’Ottawa/University of Ottawa

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Citizen science can help prepare for future flooding in Rainy-Lake of the Woods

Read the full story from the International Joint Commission.

Fort Frances, Ontario, and International Falls, Minnesota, were the sites of listening sessions in August by the International Rainy-Lake of the Woods Watershed Board.

The focus was on major flooding in the spring of 2022 that affected the region for months.

The board’s Water Levels Committee presented a video on the flood event and community members shared views and concerns to help inform a post-flood report being prepared for the board. Meteorologists at the meeting said basin residents can participate by getting involved in snowpack measuring as citizen scientists.

Change in Ontario planning regulations could kill millions of birds along the Atlantic Flyway

Read the full story from Treehugger.

The government of Ontario, Canada introduced Bill 23 (“More Homes Built Faster Act”) to remove restrictions that they claim are driving up the cost of housing and slowing construction. There are many parts of the act that are causing shock and horror among environmentalists and urbanists in Ontario, but there are some that have a much wider reach than just the province.

One of the major features of the act is to remove the authority of municipalities to develop their own green standards that differ from the provincial standards. When questioned, the office of the Housing Ministry told The Star that “if municipalities create their own standards, this patchwork of energy efficiency and other requirements reduces consistency and erodes affordability.”

One of those municipal standards that are threatened is Toronto’s Bird Friendly Guidelines. Toronto and the land around it are smack in the middle of the Atlantic Flyway, a major migration route running from the Arctic to South America, with many of them flying over New York City.

Canada to ban making, importing many single-use plastics from Dec

Read the full story at Reuters.

The government of Canada on Monday published final regulations to prohibit “harmful” single-use plastics, with a ban on manufacturing and importing most of these items to come into effect in December.

The ban will be on single-use plastics including checkout bags, cutlery, food-service ware made from or containing plastic that is hard to recycle, ring carriers, stir sticks and straws, the Canadian government said in a statement.

Plovers quarrel: A tiny, endangered bird returns to Sauble Beach to find sunbathers dug into the sand

Read the full story at The Narwhal.

Fined $100,000 for destroying piping plover habitat, the Town of South Bruce Peninsula is in court arguing over just what an Ontario beach should be.

Clean technology in manufacturing

Read the full story at PLANT.

Recently, PLANT held a roundtable looking at the adoption of clean technology in the manufacturing space, focusing on how manufacturers can be more sustainable and reduce their carbon footprint. This included a look at using renewable energy, how plants are becoming carbon neutral, and what companies are doing to help. PLANT also dived into the electric vehicle sector and how it is affecting the clean technology space in Canada.

The frontline of conservation: how Indigenous guardians are reinforcing sovereignty and science on their lands

Read the full story at The Narwhal.

From catching poachers to documenting species to saving lives, guardians all along the B.C. coast are bringing back traditional practices of territorial safeguarding — and filling major knowledge and conservation gaps while they’re at it

Diageo to build $245 million carbon neutral distillery in Canada

Read the full story at ESG Today.

Global spirits and beer company Diageo announced today plans to build a CAD$245 million carbon neutral distillery in Canada for its Crown Royal Canadian Whisky brand. Located in St. Clair Township, Ontario, the facility will operate with 100% renewable energy and will have the capacity to produce up to 20 million litres of absolute alcohol (LAA) annually.

Government supports efforts to reduce food waste and enhance sustainability

Read the full story from Agriculture and Agri-Food Canada.

Today, the Honourable Marie-Claude Bibeau, Minister of Agriculture and Agri-Food, announced up to $1,545,000 in funding for Outcast Foods Inc. to expand their operations in food waste reduction that upcycles surplus and unsaleable fruits and vegetables from growers, processors and retailers into dried, plant-based powders and solid food ingredients.

Doctors in Canada can now prescribe national park passes to patients

Read the full story in the Washington Post.

A trip to the doctor can yield any number of recommendations, including bed rest and medicine. But as of late January, Canadian patients can be sent home with a more novel note: a prescription for a national parks pass.