The fate of a dozen alpine plant species in the San Juan Mountains could be determined by how well they adapt to an environment in which early snowmelt increases competition for nutrients, says an ecologist who has studied the effects of snow, summer rain and temperature on tundra environments in Colorado, Alaska and Greenland.
Heidi Steltzer, a biology professor at Fort Lewis College, will discuss the research she did last summer in Senator Beck Basin near Red Mountain Pass north of Silverton. She will speak from 7 to 9 p.m. today at Silverton Town Hall. The presentation is the last in the Moving Mountain Education Seminar series sponsored by the Mountain Studies Institute.
"I piggybacked on a study of the effects of dust on the timing of snowmelt by Tom Painter, a professor at the University of Utah, and Chris Landry of the Center for Snow and Avalanche Studies," Steltzer said in a campus interview Monday. "We still have to think through what the ecological consequences of the plant study are."
Steltzer received her doctoral degree in biology at the University of Colorado at Boulder. Before joining the FLC faculty, Steltzer studied the effects of climate change on vegetation in Noatak National Park in Alaska, where trees have moved upslope into tundra and how warming temperatures and increasing rain affected plants in Thule, Greenland, a site near the northern limit of plants.
Steltzer's study in the San Juan Mountains involved creating four environments to test the effects of when snow melts on plant life. It was based on research by Painter, Landry and others who say dust storms that sweep the San Juan Mountains cause the snow to melt earlier, an occurrence particularly noticeable this year.
A coating of dust absorbs the sun's rays instead of reflecting them back into the atmosphere like clean, white snow does.
Thirteen 24-foot by 36-foot experimental areas were created, Steltzer said. Over some, a dark fabric was installed to mimic dust; others were left with the dust from natural storms. In a third plot, snow was covered with dust manufactured by grinding up rock of the basin. Finally in a fourth plot, a few centimeters of dust-covered snow were removed to leave pristine snow.
As winter ended, the first areas to become snow-free were the ones covered with fabric, followed in order by areas covered with the manufactured dust, areas with wind-blown dust and lastly the areas with no dust cover.
The total time elapsed from when the first area became snow-free to the last was 44 days - from June 1 to July 15.
"We expected them to become snow-free in that order," Steltzer said. "But something occurred that we didn't expect."
Vegetation didn't produce leaves and blooms in the order in which they became snow-free.
"We expected to see green-up (leaves) earlier in plots where snow was gone earlier," Steltzer said. "But we found that all the plots, which became snow-free at different times, greened up at the same time. The appearance of alpine flowers also was not staggered but synchronous.
"This is a change from the way alpine landscapes react normally," Steltzer said. "It appears that the cue for plants to begin growing new leaves is temperature, not when desert dust leads to earlier snowmelt."
If further research confirms the findings, it could mean that alpine plant species will green up and flower at the same time and thus compete for water and nitrogen in the soil, with the less competitive plants less likely to survive, Steltzer said. Such a scenario also could have implications for the pika, a small rabbit relative that lives in rocky alpine habitat, and elk that feed on alpine vegetation.
Among the dozen plants species studied are the alpine avens, American bistort, alpine sage, marsh marigold, Indian paintbrush and alpine sunflower.
A number of researchers say the unusual number of dust storms early this year in the San Juan Mountains - a dozen compared to three or four in past seasons - added such a heat-absorbing snow cover that the snow melted a month earlier than usual.
Researchers say that sediment cores from high-elevation lakes in the San Juans show wind-blown dust is as much as five times the amount before Europeans arrived. The westward migration and later activities such as cattle grazing, oil and gas exploration and off-road vehicles are the cause of the increase in dust, researchers say. Spokesmen for the special interests say they aren't to blame.