To study the effects of longer and hotter summers, ecologists drag 5,000 pounds of sand up a mountain

Will Fuller and Miles Moore measure snow depth on a test plot in New Ridge. Credit: Kelsey Simpkins/CU Boulder

With temperatures soaring in early September, it’s clear that Colorado’s summers are lasting longer. They also started early, with mountain snow melting in May instead of June.

As spring begins in summer each year on Niwot Ridge, just north of Nederland, icy snows give way to small shrubs and colorful lichens on this exposed, reef-like tundra 10,000 feet above sea level. A portion of the landscape will soon also be covered in what looks like heaps of chocolate chip ice cream.

Over the past five years, a small team of research assistants and volunteers has climbed Newt Ridge in late May to pave the way for a unique experiment in which they deployed 5,000 pounds of lions sand Cross parts of the remaining snow mass.

Their goal? To simulate the not-too-distant future impacts of a warming planet on alpine ecosystems. Researchers want to know what might happen when mountain ice melts sooner and summer lasts longer each year due to higher temperatures than Climate change.






“We’re seeing a huge impact from these long summers. When things warm up and thaw earlier, those years really seem to affect the system—the plants, the pica, the water qualitysaid Catherine Sodding, principal investigator on the project, and Professor of Excellence in the Department of Ecology and Evolutionary Biology and the Institute for Arctic and Alpine Research (INSTAAR). “And the best way to find out what might happen in the future is to test it.”

The Suding team uses simple, cheap and environmentally friendly sand to naturally attract and heat more sunlight. the snow and dissolve faster. It is made of the same glassy silica particles used in fire pits and dusters.

To study the effects of longer and hotter summers, ecologists drag 5,000 pounds of sand up a mountain

Jimmy Howe and team members apply black sand to an experimental plot of land in New Ridge. Credit: Kelsey Simpkins/CU Boulder

Each season, the team distributes sand over snow in five test pieces across the hills, leaving some snow next to it untouched. Throughout the summer, dozens of graduate students, volunteers, and faculty operate soil sensors, collect plants and gather data on pollinators to see what kinds, if any, changes are being caused by early thaw in the tundra beneath.

This project is just one of dozens of research projects conducted by University of Colorado Boulder scientists and partner institutions at the century-old Mountain Research Station. This effort is also part of the Niwot Long-term Ecological Research Program.

“It’s a very ambitious project,” said Jennifer Morse, a climate technician at the Mountain Research Station, which is overseeing the implementation of experiments like this.

To study the effects of longer and hotter summers, ecologists drag 5,000 pounds of sand up a mountain

Miles Moore and Jimmy Howe dump black sand on a test plot in New Ridge. Credit: Kelsey Simpkins/CU Boulder

simulation of early thaw

Peak snow mass usually occurs in late May or early June, although at first it may seem like a misnomer. While the snow is still yards deep in some places, requiring crossing snowshoes or sleds, it is long gone in other places. The goal is to put in the sand when the snow stops accumulating and instead begins to melt, so the sand they use is not covered by additional snowfall.

This timing makes for a massive achievement. Pulling 5,000 pounds of sand up the mountain in late spring requires a versatile mission vehicle (UTV) with snow handling, as wind-swept mounds of snow and melting all the way from the station to the sites would be impossible for an ordinary car.

Once the researchers have hiked or skated down the ridge, they visit each of the five test plots over the course of a few days. They first collect snow depth measurements at set intervals on either side of each test chart, which they will do every two weeks until the snow melts completely.

To study the effects of longer and hotter summers, ecologists drag 5,000 pounds of sand up a mountain

Samuel Levac carries bags of black sand to where he will place them on top of the snowpack. Credit: Kelsey Simpkins/CU Boulder

Then the researchers extracted 50-pound bags of black sand from the large boxes used to transport them to the hills. They position themselves along the edges of one half of the test outline, being careful not to get into it. Then with great enthusiasm, they threw a handful of sand in the air and walked out on the snow. As it lands, it’s included in moist white stuff like sprinkles of black candy. They work around the plot to unload 10 bags of sand — 500 pounds each — to create a giant rectangle that looks like a mountain-sized tub of biscuits and cream.

The method mimics a natural phenomenonDust storms sometimes blow a thin layer of dust or sand over mountain snow, causing it to melt faster. But it’s all done by hand for the sake of this experience, and it’s hard work hauling around heavy bags of sand—especially at 10,000 feet above sea level.

“Even the simple thing here is tough,” said Samuel Yvak, professional research assistant and field leader for lagoon science at Niwot Ridge Long Term Ecological Research (LTER), as he leads the application of blank sand in several test pieces on May 17, 2022.

Over the next month or two, snow melts on both sides of the plot – but the side with black sand melts faster. Even after one week, the black sand-covered side on one of the southeast-facing vaults in mid-May had disappeared.

To study the effects of longer and hotter summers, ecologists drag 5,000 pounds of sand up a mountain

Will Fuller holds a handful of black sand, before tossing it over the snow. Credit: Kelsey Simpkins/CU Boulder

“White reflects more light, and darker colors absorb more light, so spreading sand on top will make the snow melt faster, which simulates early snowmelt. This helps us think about climate warming and where we’re headed in Levac,” said Levac. We will see more and more early snow melt.”

When all the snow melts on both sides, they spread an equal amount of sand (another 500 pounds) on the control side of the plot to nullify any effects of the sand itself on their data collection.

The speed of changing seasons

Suding hopes to better understand how this increase in the speed of snowmelt affects the vegetation beneath it, and the soil and water downstream. She is already seeing some small changes.

“The growing season starts earlier, things grow faster, and they have a longer period of growth,” Soding said. “But the other interesting thing that happens is that the plants shut down earlier. What we think happens is that the soil dries out earlier, and it’s the moisture stress that ends the growing season. So we go early in the season, but it also affects towards the end of summer.” .

To study the effects of longer and hotter summers, ecologists drag 5,000 pounds of sand up a mountain

The south-facing plot shows how quickly the sand-covered part is melting. Credit: Kelsey Simpkins/CU Boulder

The black sand experiment will continue for another two or three years, until the sand has accumulated enough that it can affect data collection. But the work will continue through the following experiments that Suding and others at Mountain Research Station use to answer questions that arise from this work. The experience will also help inform those who live downstream, including the city of Boulder and its water department.

“Early thawing in Newt Ridge affects the amount of water Boulder receives and the quality of the water,” Sodding said.

Because it is one of the most biodiverse areas in Boulder County, understanding changes in the Newt Ridge ecosystem could help Rocky Mountain National Park manage its natural resources in the North and even inform urban groups like the Denver Botanical Society for decades to come.

“Many of our partners want to make evidence-based decisions about how they manage their natural resources,” Soding said.


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