Blue sky over a snowy forest.

The boreal forests of North America are shrinking

the Boreal snow forests, also called boreal forests, in North America, is part of the largest wild biome in the world – the Global Boreal Forest. Boreal forests are found in the high northern latitudes between 50°N and 70°N latitude.

Biome, also known as taigaIt covers most of the interior of Canada, Alaska, part of the contiguous United States, most of Scandinavia, most of Russia (including Siberia), forested parts of Iceland, northern parts of the Scottish Highlands, Kazakhstan, Mongolia, and Japan.

Boreal forests are often referred to as “snow forests” due to the large and continuous snow cover they receive during the long, cold winters. The term reflects the climatic characteristics of the biome, where winter is dominant and snow can persist for several months.

Long, cold and snowy winters are characteristic of the boreal forest climate. Photo: Denali National Park, Tim Raines/NPS, public domain.

What are boreal forests?

The northern climate is characterized by long, cold winters and short, mild summers, which greatly affects the types of plant and animal life that can thrive there.

The basic types of boreal forests are coniferous trees; It adapts to cold temperatures throughout most of the year. fir trees It makes up most of the taiga in North America.

Boreal forests of North America

The boreal forest in North America represents a large part of the boreal biome or global taiga, stretching across Canada and into the US state of Alaska. This area includes approximately 1.5 billion acres of dense coniferous forests consisting mainly of species such as spruce, fir, and pine.

Shaded relief map of the northern part of the United States and Canada showing areas in green that are boreal and semi-deciduous forests.
Map of the northern region of North America. Data were developed from Natural Resources Canada for Brandt, JP (2009). Northern region extent of North America. Environmental Reviews, 17(NA), 101-161.

The ecosystem is cold-adapted, with long, harsh winters and short, mild summers, and provides critical habitat for a variety of wildlife, including large mammal species such as moose, caribou, and wolves.

In addition, the boreal forests of North America serve as a vital carbon store, sequestering large amounts of carbon dioxide, and playing an essential role in regulating the continent’s climate and hydrological cycle.

did you know 5.5 million square kilometers of boreal forests in North America lie within Canadian territory, while 0.74 million square kilometers belong to the United States (mostly in Alaska).

The impact of climate change on the boreal forests of North America

Because the boreal forest biome relies on long and stable cold or cold seasons, it is highly vulnerable to global warming and its effects – heatwaves, droughts, wildfires, and shrinking snow cover.

Predictions about the change of boreal forest habitats in North America under the influence of climate change were clear and based on commonsense assumptions – but perhaps a little naive from a new perspective.

What the research says about changes in the range of boreal forests with climate change

Despite the shrinkage and disappearance across the southern line, it was expected that The northern line will move from boreal forests farther north, replacing arctic bush and tundra that are supposed to be shrinking Because of the now longer and warmer growing season. In this scenario, forests would lose some of their range, but would compensate for a significant portion of it by moving north, in line with the changing temperatures.

However, actual field research does not confirm this idea. Instead, it tells us that The boreal forests of North America appear to be shrinking Losing the southern part of the range and not gaining much northern territory.

And that is exactly the title of the pilot study,”Northern expansion does not compensate for the southern decline in the boreal forests of North America,She suggests. Made by Ronnie Rothbarth Department of Environmental Sciences at Wageningen University (Netherlands) and his team W Posted in Nature Communications.

Using remote sensing to map changes in the extent of boreal forests in North America

Use the team remote sensing data – specially, MODIS continuous vegetation field – l Tree cover analysis Thus measuring changes across the American portion of the northern biome 2000 to 2019. Moreover, they looked at the relationships between these changes and environmental factors, such as temperature, precipitation, and albedo, as well as their association with disturbances such as wildfire damage and timber exploitation.

What they found was a strong distinction between changes in the snowy forest’s southern and northern borders – and they called it “”North-south asymmetry in tree cover change.

The southern boundary of the range declined as expected, with widespread forest fires caused by global warming being one of the main causes (along with the failure of the original forest to regenerate). This part of the boreal forest is increasingly under pressure from warmer and drier conditions, resulting in reduced growth rates, decreased vigor, insect infestations, and an increased rate of tree death.

By contrast, the new conditions benefit many temperate broadleaf species that are gradually replacing the lost cold-adapted conifers. However, not all of this decline was due to climate change; It is also revealed that logging plays a big role.

On the other hand, there was There is no evidence of expanding tree cover at the biome’s northern boundary.

The expansion of conifers in inhospitable boreal and high latitude regions is a very slow process, and depends on many factors. Other studies have already shown that boreal forests do not always track the expansion of their climatic environment along the northern boundary.

One hypothesis is that for trees to grow, the shrubs that protect the seedlings from the elements must move in first. but, Permafrost collapse and surface water accumulation Which comes with it seems to lead to Browning of new shrubs and trees, which may limit the northward expansion of boreal forests.

The only place covered by a tree Significantly increased core biome scale.

Diagram showing current, projected, and observed latitudinal changes for boreal forests in North America with green trees for boreal, cloud/ice icons for tundra, and dark yellow trees for temperate trees.
Diagram showing current, projected, and observed latitudinal changes for boreal forests in North America. Graph (a) shows the current range. Graph (b) shows the projected northward shift of the boreal forest as it shrinks south. Graph C shows what remote sensing observations show, that boreal forests shrank southward but did not expand northward into the tundra habitat. Charts: Rothbarth et al., 2023, CC BY 4.0.

The team suggests that the results of their study could indicate that rather than the expected northward migration, the shrinkage of the biome is either coming or is already occurring.

Consequences of shrinking snowy forest range

Shrinkage of snowy forests could have dire consequences for biodiversity on the continent. It represents the boreal forests of North America A quarter of the world’s intact forestswith 80% of its territory is considered intact (However, only 8-13 percent enjoy formal protection.)

Let’s take a look at some examples.

  • The boreal forests of North America still facilitate some of the The longest migrations of mammals and fish in the world (Think salmon).
  • The biome is one of the rare places on Earth from which a remnant remains Fixed number of large predators such as wolves, bears, lynxes, etc., resulting in a natural predator-prey balance and healthy, functional ecosystems.
  • It is a seasonal home for 1-3 billion birds nest in AmericaMost of which are completely dependent on snowy forests as their obligatory nesting place.
  • The snowy forest area contains some The largest lakes in the world and the longest non-dammed riversWhich led to an abundance of aquatic organisms.

As a result, the biome can shrink Affects millions of people who depend on forests and their biodiversity for their livelihoodsmany of them the original people And they still graze a traditional way of life (most of Canada’s boreal forests are on Aboriginal lands).

Indigenous governments have joined scientific conservation efforts to preserve their pristine landscapes; Synergy has led to the creation of some of the largest land conservation projects in the world. However, with resources such as timber, minerals and hydroelectric power, the boreal forests are intact It remains a lucrative area for the extractive and exploitative industriesThis led to an increase in industrial activity that often lacks environmentally friendly land management.

The fact is that the northern forests too Storing huge amounts of carbon It is also a cause for concern. Large portions of stored carbon are found in Biomass From the forest itself (approx 15 billion metric tons), and even more so in permanently frozen soil (permafrost) under it.

Photo of a swamp in the foreground and a boreal forest in the background in the interior of Alaska.
Introduction This image of Inland Alaska is a non-permafrost swamp bordered by a boreal forest growing in permafrost. Photo: Christine Manes, USGS, public domain.

Shrinking range of glacial forests will impair tree carbon storage and sequestration capabilities, but perhaps more worrisome will cause carbon stored in permafrost to be released.

Unless this carbon emission is offset by carbon gains elsewhere, it will inevitably accelerate global warming. It basically creates a Snowy Forest negative feedback loop – As global warming intensifies, forests die and release more carbon, leading to more escalating climate change that destroys them.



Rothbarth, R., Van Ness, EH, Schaefer, M. et al. (2023) Northern expansion does not compensate for southern decline in boreal forests in North America. Nat Common 14, 3373.

Wells, JV, Dawson, N., et al. (2020) The Conservation State of the North American Boreal Forest: Issues and Opportunities. Before. to. Earth. Altaghyeer, 30 July 2020. Sec. Temperate and Boreal Forests Volume 3 – 2020 |

USGCRP, 2018: State of the Carbon Cycle II Report (SOCCR2): A Sustainability Assessment Report. Chapter 11: Carbon in the Arctic and North Pole. [Cavallaro, N., G. Shrestha, R. Birdsey, M. A. Mayes, R. G. Najjar, S. C. Reed, P. Romero-Lankao, and Z. Zhu (eds.)]. American Program for Global Change Research, Washington, D.C., USA, 878 pages, doi: 10.7930/SOCCR2.2018


Nick Ogasa. Snowy forests in North America may be about to shrink. Science news. June 29, 2023

MODIS Continuous Fields of Vegetation. NASA Modis.



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