Climate change could allow sugar maples to thrive along Hudson Bay coast

Canada's national symbol seen heading north


By 2100, sugar maples may grow along the Hudson Bay coast as far north as Inukjuak in northern Quebec.

A projected warming of the climate, showing average temperature increases of 5.6° C, means sugar maples could thrive 1,000 km further north than from where they do today in southern Quebec.

"However, I wouldn't want to be suggesting that people are going to be harvesting maple syrup at the end of the century because it takes a long time for the trees to grow," said Daniel W. McKenney of the Canadian Forest Service.

McKenney and his colleagues, who studied 130 North American tree species, expect climate changes this century could shift tree ranges northward by hundreds of kilometres.

This wouldn't be the first time that trees have grown in higher latitudes. More than 45 million years ago, redwoods and other trees grew in Nunavut's High Arctic region and their fossilized trunks can still be seen on remote slopes.

Yet the vision of sugar maples, Canada's national symbol, growing in the treeless Arctic, provides a strong image of the scale of the warming that may lie ahead.

This is particularly true in Nunavik, where some climate change projections now show a 12° C increase in average temperatures by 2080.

Other trees that would be likely to grow in a warmer Nunavik include oak, willows and conifers, which would be able grow faster and taller than is now the case along the tree line.

The trees would be able to adjust to lower light in the winter as they do in northern Norway and Finland, where trees grow above the Arctic Circle.

However, the climate may warm more quickly than the trees now found in the South can cope with, McKenney cautions. If the climate zone they grow in moves 1,000 km north in the next 100 years, trees, which only move an average of 50 km in 100 years, won't be able to keep up.

"It's a lot faster shift in the climate than what the plants are going to be able to do," McKenney said.

Tree planting may help trees move northward more rapidly – although it's too early now to start nurseries for seedlings, McKenney warned.

"The projections have things changing more quickly as the century goes on," he said. "The change will ramp up, so have to be careful in trying to plant things."

Fires, soil conditions and wind may also affect trees' ability to grow in the higher latitudes.

"For them to grow really well is a different question for them just to be there," McKenney said.

However, trees may prove to be more hardy than is generally thought. A birch tree growing in the shelter of a house in Puvirnituq shows it's possible even now for a tree to grow along the Hudson Bay coast.

For his research, McKenney looked at a set of climate conditions that included temperature and precipitation. He based his temperature projects on scenarios from the Canadian Centre for Climate Modelling and Analysis and the United Nations' Intergovernmental Panel on Climate Change.

The main climate change scenario used in the research was considered extreme at the time, McKenney said, but is now regarded as conservative.

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