Over the past 30 years, three-quarters of eastern US tree species have been shifting to the west, and at an astonishing rate of around 15.4 kilometers per decade (9.5 miles). That’s weird, because scientists have long predicted that the effects of climate change would send species towards the poles in search of familiar climates, but since 1980, more eastern trees have been moving west instead of north. And at this stage, it’s not entirely clear why.
And the fact that more eastern trees are moving westward than northward isn’t even the strangest part. Researchers estimate that even if we took certain knock-on effects of climate change into consideration, such as changes in rainfall and precipitation, it can only explain a fraction of the movement.
Something else is going on here – or many somethings in accumulation – and scientists are still trying to make sense of it. “[It] was a huge surprise for us,” lead researcher Songlin Fei, a forest ecologist from Purdue University, told Emma Marris at Nature.
Fei and his team analyzed 30 years’ worth of data from the US Forest Service, which covered the movements of 86 tree species between 1980 and 2015. These trees were located between Maine and Minnesota, and as far south as Florida.
They found that more species had made shifts towards the west than to the north during this period, and the young trees were more likely to have made this westward migration than the older ones. Some trees made their way in both directions, towards the northwest.
From Science Alert: https://www.sciencealert.com/american-trees-have-started-migrating-west-and-no-one-knows-why