A warmer world is making high latitude forests more deciduous and less evergreen, research shows. Global heating has increased the likelihood of extreme events such as wildfires and storms and this warmer and less stable environment is favouring deciduous trees over evergreens.

Boreal forest stretches for miles and miles across high northern latitudes, covering huge swathes of Canada, Russia, Alaska and Scandinavia. It makes up nearly a third of global forest area and is mainly made up of evergreen trees such as spruce and fir. But this landscape could change.

Researchers used a vegetation model to investigate the likely impact of climate warming on boreal forest over the 21st and 22nd centuries. Their findings, published in the Journal of Geophysical Research: Biogeosciences, show that after disturbances like wildfire and storms, deciduous trees establish more quickly and start to dominate. Rising temperatures also assist by extending the growing season and increasing nitrogen in the soil, both of which disproportionately benefit deciduous trees.

Data from Alaska and Canada indicates this transition is already under way, with a shift towards more deciduous saplings in a number of areas, with implications for carbon, water and energy cycles in these regions. Evergreens will not disappear completely, but the model suggests they will no longer be the dominant tree in boreal regions.