Moderate heat, rain could damage Earth's forests

Moderate heat, rain could damage Earth's forests

PARIS: Even relatively moderate heat and rainfall loss could damage the make-up of Earth's northern forests, risking their biodiversity rich ecosystems and disrupting their ability to store climate-warming carbon pollution, researchers said on Wednesday Aug 10. 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 conducted a five-year experiment to assess how higher temperatures and less rainfall could affect the tree species most commonly found in the forests.

Between 2012 and 2016 they grew approximately 4,600 saplings of nine tree species - including spruce, fir and pine - in forest sites in northeastern Minnesota.

The saplings were warmed at two different temperatures using undersoil cables and infrared lamps - 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.

Even trees grown under 1.6 degrees Celsius of warming experienced major problems, including reduced growth and increased mortality, according to a study published in Nature.

Peter Reich, lead author, told AFP that we would see modest declines in survival and growth for even the boreal species like fir, but we saw very large increases in mortality and decreases in growth in a number of species.

The team found that warming on its own, or combined with reduced rainfall, increased juvenile mortality in all nine tree species studied.