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Details on AMC's research on climate change and alpine ecosystems can be found at outdoors.org /conservation/airwater/climate-research.cfm.

No one tends the Alpine Garden on the southeastern shoulder of Mount Washington. But the diminutive plants there may be receiving a dose of nitrogen as they might if they were in a backyard flowerbed—and that may not be a good thing.

That nitrogen isn't coming from a bag of fertilizer and it's not being applied by human hands. But it is likely the result of human activity—the burning of fossil fuels—and it's coming in on the wind in the form of nitrogen pollution.

These are some of the findings of AMC researchers engaged in the third year of a three-year National Oceanic and Atmospheric Administration-funded study of climate impacts on the alpine zone. AMC's two partners in the study are the Mount Washington Observatory and Plymouth State University.

Of particular concern is the potential effect of the airborne nitrogen on alpine plant species in their above-treeline environment. "Nitrogen is a key ingredient in fertilizer. When you add fertilizer to a system, you change the likelihood a species has to make it or not make it," says AMC Director of Research Ken Kimball. "It has the potential to change the competition of plants in an ecosystem," he explains.

Kimball says he and others are asking, "How serious is this nitrogen, and may it play a role in changing our alpine communities?"

In addition, unlike in lower elevation areas, the researchers have not found significant climate warming at higher elevations on Mount Washington over several decades. But they have found that air pollution levels are greater at higher elevations. This is attributed to stratification of air masses, which creates what is known as the atmospheric boundary layer.

While stratification may curb climate change in mountain ecosystems, air pollutants—such as nitrogen emitted from automobiles and power plants—can rise above the boundary layer and be carried to the mountains on prevailing winds from urban and industrial corridors to the west. "Stratification separates lower and upper warming trends, but stratification allows more pollutants to come in at higher levels at higher elevations," says Kimball.

In a related effort at AMC's Highland Center at Crawford Notch, the organization recently hosted a National Science Foundation-funded workshop on alpine and subalpine ecosystems that brought together researchers and mountain ecologists from the United States, Canada, and Europe. Researchers studying high-elevation nitrogen pollution in the Rocky Mountains contributed regional insight. Kimball said the Northeast mountains receive comparatively higher amounts of nitrogen pollution than do the Rockies.

Going forward, workshop participants "will identify research gaps that need to be filled to better understand how the region's alpine and subalpine ecosystems have survived at such low elevations since the last glacial period, and how susceptible they are to climatic change and air pollution," Kimball says. "If we are to better predict the long-term viability of these special ecosystems, we must have the underpinnings of good and focused science."