PARIS: Even relatively moderate heating and rainfall loss could affect the make up of Earth's northern forests, risking their biodiversity rich ecosystems and undermining their ability to store planet-warming carbon pollution, researchers said Wednesday. Boreal forests cover much of Russia, Alaska and Canada and are a major carbon sink, but are threatened by more frequent wildfires and invasive species outbreaks linked to climate change.
A team of researchers from the United States and Australia have conducted a five-year experiment to assess how higher temperatures and less rainfall may affect the tree species most commonly found in the forests.
Between 2012 and 2016 they grew over 4,600 saplings of nine tree species - including spruce, fir and pine - in forest sites in northeastern Minnesota.
The saplings were warmed around the clock at two different temperatures - one lot at 1.6 degrees Celsius hotter than ambient, the second at 3.1 degrees Celsius warmer.
In addition to this, moveable tarps were positioned over half of the plots before the storms to capture rainwater and mimic the type of precipitation shifts that climate change is anticipated to bring.
The study, published in Nature, found that trees grown under 1.6 degrees Celsius of warming experienced major problems, including reduced growth and increased mortality.
We thought we'd see modest declines in survival and growth for even the boreal species such as spruce and fir, but we saw very large increases in mortality and decreases in growth in a number of species, lead author Peter Reich told AFP.
The team found that warming on its own, or combined with reduced rainfall, increased juvenile mortality in all nine tree species studied.