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Yosemite Giant Pines Disappearing -- BBC - Earth News
Climate change appears to be a major cause of the loss.
The revelation comes from an analysis of data collected over 60 years by forest ecologists.
They say one worrying aspect of the decline is that it is happening within one of most protected forests within the US, suggesting that even more large trees may be dying off elsewhere.
James Lutz and Jerry Franklin of the University of Washington, Seattle, US and Jan van Wagtendonk of the Yosemite Field Station of the US Geological Survey, based in El Portal, California collated data on tree growth within the park gathered from the 1930s onwards.
Their key finding is that the density of large diameter trees has fallen by 24% between the 1930s and 1990s, within all types of forest.
"These large, old trees have lived centuries and experienced many dry and wet periods," says Lutz. "So it is quite a surprise that recent conditions are such that these long-term survivors have been affected."
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