Satellites show changing vegetation norms

GREENBELT, Md., Dec. 8 (UPI) -- Scientists say satellite data show 20 years of warming temperatures in Quebec have resulted in an increase in the amount of shrubs and grasses.

Researchers say NASA Landsat missions revealed increased vegetation in the north of the province between 1986 and 2004.

The study is one of the first to present a detailed view of how warmer temperatures are influencing plant distribution and density in northern areas of North America, a NASA release said Thursday.

"Unlike the decline of sea ice, which is a dramatic effect that we're seeing as a result of global warming, the changes in vegetation have been subtle," Jeff Masek, the program's project scientist, said.

"For the first time, we've been able to map this change in detail, and it's because of the spatial resolution and length-of-record that you can get with Landsat," he said.

By using Landsat's higher optical resolution and viewing the same area at the same time for 23 years, Masek and his colleagues were able to track the areas as they continued to show more "greenness" over the years.

"It makes sense," Masek said. "This is how shrub encroaching occurs. They increase in size, they increase in density, and then they move northward."