Forests from the Arctic to the Amazon are being transformed at a “shocking” rate due to the climate crisis, with trees advancing into previously barren tundra in the north while dying from rising heat further south, researchers have found. scientists.
Global warming, along with changes in soils, wind and available nutrients, is rapidly changing the composition of forests, making them far less resilient and prone to disease, according to a series of studies that have looked at the health of forests. trees in North and South America. .
Many forest areas are now becoming more susceptible to fierce wildfires, causing more greenhouse gases to be released from these vast carbon stores further warming the planet. “It’s like humans have struck a match and now we’re seeing the result of that,” said Roman Dial, a biologist at Alaska Pacific University.
Dial and his colleagues have found that a patch of white spruce in northwestern Alaska has “jumped” north into an area of arctic tundra that hasn’t had such trees in millennia. The new research work of scientists, posted in Natureestimates that spruce trees are advancing north at a rate of around four kilometers per decade, aided by warmer temperatures and changes in snow and wind patterns influenced by shrinking sea ice in the region.
“It was shocking to see trees there. No one knew about them, but they were young and growing fast,” said Dial, who first saw the shadows of the trees on satellite images and then took a trip in a single-engine plane, followed by a five-day trek, to find and study the advance of the forest.
“The trees were basically jumping over the mountains into the tundra. According to climate models, this was not supposed to happen for another hundred years or more. And yet it is happening now.”
the arctic is warming several times faster than the global average and the appearance of dark conifers on the once pristine white tundra threatens to absorb, rather than reflect, more sunlight, causing further warming. Trees can also disturb the migration of various local species. “These trees are moving very fast,” Dial said.
Further south, separate investigation has found A transformation is taking place at the boundary between boreal and temperate forests, with spruce and fir species increasingly unable to cope with warmer conditions. Scientists estimate that even small amounts of additional warming caused by human activity could cause up to 50 percent of traditional boreal forest trees to die in certain locations, and many other trees to be stunted.
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“Boreal species are doing very poorly with even modest warming. They grow more slowly and have higher mortality,” said Peter Reich, a researcher at the University of Minnesota and co-author of the research. “Intuitively, I thought they would do a little worse with 1.5C of warming, but they do a lot worse, which is worrying.”
Reich and his colleagues spent five years raising nine different tree species from seedlings in different conditions in northern Minnesota, subjecting them to different amounts of heat and water. Boreal species were found to suffer when soils dried out due to heat, while other more temperate species, such as oak and maple, were able to cope better and may slowly shift to the boreal zone as the world gets warmer. .
“Given how fast climate change is, we could have a 50- to 150-year period where spruces and firs for thousands of miles, even from Siberia to Scandinavia, don’t regenerate, so you’re going to have this strange new invasive system. bushes that will not provide us with the economic and ecological services that we are used to,” said Reich.
The impact of the climate crisis is also being felt in the heart of the Amazon, another study underlined. Scientists have raised concerns that the huge rainforest ecosystem is in danger of leaning into a new altered stateeventually becoming a savannah, and the new research found that the lack of phosphorus in the soils of the Amazon could have “important implications” for its resistance to global warming.