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Global warming: Trees are invading mountain meadows

Longer growing seasons enabling seedlings to take hold

Some mountain meadows in the American West may disappear, as trees start to take root due to shorter winters and warmer temperatures. Bob Berwyn photo.

FRISCO — As the Earth steadily warms, snowpacks are dwindling, especially in spring, leading to a longer growing season that enables trees to replace grasses and wildflowers by taking root in high mountain meadows.

A new study by Oregon State University researchers suggests the tree invasion has been accelerating the past few decades, at least in the Pacific Northwest, where the scientists reported the results of a long-term monitoring project in Jefferson Park, a subalpine meadow complex in the central Oregon Cascade Range, where tree occupation rose from 8 percent in 1950 to 35 percent in 2007.

“We worry a lot about the loss of old-growth forests, but have overlooked declines in our meadows, which are also areas of conservation concern,” said Harold Zald, a research associate in the College of Forestry at Oregon State University and lead author of this study. Continue reading

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Global warming: Alpine flora facing uncertain future

Some Alpine plant species are likely to become isolated in climatic traps. PHOTO BY BOB BERWYN.

Delayed response to climate change could leave some species isolated in climatic traps

By Summit Voice

SUMMIT COUNTY — A new study of Alpine plants by Austrian ecologists suggests that some current climate models may over-estimate the rate of habitat loss resulting from global warming in the next few decades.

But the long-term impact is still likely to be the loss of many species that live in narrow ecological niches that will mostly be lost as the climate continues to warm. There may be a delayed response in some species that will be able to hang on in tiny microclimates as the ecosystems around them change, but they to will be lost due to an inability to disperse across any significant distance, according to ecologists from the Department of Conservation Biology, Vegetation and Landscape Ecology of the University of Vienna.

The results of the study, published in Nature Climate Change, suggest that, by the end of the 21st century, high Alpine mountain flora will lose on average 44 percent to 50 percent of its current distribution area, a  moderate forecast as compared to predictions based on traditional modeling techniques. Continue reading

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