Niwot Ridge is the longest-running multidisciplinary, long-term alpine and sub-alpine study site on the continent, Williams said. In addition to evidence for recent climate warming, the Niwot Ridge region also has seen a four-fold increase in the deposition of atmospheric nitrogen in the past 20 years, believed to originate primarily from automobile, agricultural, ranching and industrial activity.
   
Photos of Young Scientists on the Tundra
"As a result, we are now seeing adverse changes in aquatic and terrestrial life in the sub-alpine and alpine environments there," he said.
The atmospheric nitrogen enhances microbial activity in the streams and lakes at the Niwot Ridge, causing shifts in the abundance of dominant algal organisms known as diatoms, he said.
"This is a warning signal to us that is coming from the bottom of the food chain," said Williams. "We could be seeing dead trout up there not too far down the road if this trend continues."
   
INSTAAR scientists working on Niwot Ridge also are beginning to see changes in the composition and diversity of alpine wildflower species, he said. While the alpine tundra has more native plant species than corresponding areas in forests or grasslands, plant species on Niwot Ridge are more susceptible to shifts in climate and pollution, he said.
 
Living in an extreme environment, alpine plants survive on limited amounts of nutrients, sunlight and moisture and are less adaptable in terms of the ecological niches they can occupy, he said. While they are genetically programmed to withstand large annual temperature swings, they are poor at tolerating extended "unidirectional changes" like warming or nitrogen pollution, Williams said.
"These are fears that some of these rare alpine species are going to be out-competed by lower elevation flowers as the temperature rises and nitrogen becomes more prevalent in the system," he said.
CU faculty and students have done research on the region's water, soil plant and wildlife resources for the past several decades, Williams said. Topics of study range from hydrology, geochemistry and nutrient transport to paleoecology, microbiology and ecology.
Niwot Ridge also is the site of one of the world's five long-term climate monitoring stations administered by the National Oceanic and Atmospheric Administration in cooperation with INSTAAR. Atmospheric CO2 levels have been monitored there since 1968, providing the second longest record in the world for the steadily increasing greenhouse gas.
Researchers also are attempting to document changes in the alpine ecosystem since the last glacial period to understand and predict future changes associated with environmental disturbances. Tree-ring studies and evidence from fossil plants, pollen and insects have allowed them to extrapolate past precipitation, temperature and other environmental conditions in the area.
The LTER site features a high-altitude, state-of-the-art alpine tundra laboratory constructed in 1990. Located at 11,565 feet, the lab allows year-round research in a harsh region where winds approach 160 mph and the wind-chill factor can dip as low as 70 degrees below zero.
The Niwot Ridge LTER website can be found at http://culter.colorado.edu
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