Professor Guofan Shao said he used remote sensing data to survey the Mount Paekdu Biosphere Reserve -- a 326,000-acre forest preserve in North Korea operated by the United Nations Educational, Scientific and Cultural Organization.
Shao said Mount Paekdu, together with an adjacent biosphere in China, has the world's highest plant biodiversity in a cool, temperate zone and is the habitat for many wildlife species, including the endangered Siberian tiger.
Shao said he and his team were studying NASA satellite data when they noticed some changes occurring to the land in North Korea. NASA images didn't have the resolution Shao needed to pinpoint what the changes were or how they were occurring, so he used Google Earth, which has a clear resolution down to 1 meter.
"Particularly in the core area, there should be no human activity -- no deforestation," Shao said. "But when you look at the data with Google Earth, you can see the forest is no longer intact."
He said the Google Earth images show extensive logging has taken place in the North Korean biosphere. Shao estimated as much as 75 percent of the forest in the core area has been removed in large strips.
The study that included researchers at the Chinese Academy of Sciences, the Jilin Changbai Mountain Academy of Sciences and Arizona State University appears in the journal Biological Conservation.
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