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$12 Bubble Machine Key to Research

Story and photo by Ellie Nesbit ’14

What can you do with a $12 bubble machine from Wal-Mart? Apparently a lot more than just blow bubbles. Just ask Colorado College Environmental Science Associate Professor Miro Kummel, who is using the device as one way to track the ways trees alter small-scale wind patterns at the tree line on Pikes Peak.

Miro Kummel works with student researchers on Pikes PeakThe bubble machine is just a small part of Kummel’s ongoing research on how climate change has affected the tree line on Pikes Peak. Kummel has been coming out to tree line for the past five years, collaborating with various groups of Colorado College students who receive Student-Faculty Collaboration Grants from the Dean's Office, and Lyddon grants, internal grants given to environmental science majors for student-faculty collaborative summer research.

Ecologists have noticed that the tree line, or the point of a habitat where trees become incapable of growing due to cold temperature, has risen as a consequence of global temperatures rising.

This summer Kummel worked with several students from Colorado College’s environmental science program to collect data on vertical wind profile, vertical and horizontal mixing, and air and soil temperatures. The team is trying to further understand the microclimatic conditions that are put into motion by the migrating tree line. As the trees warm up the surrounding area, more trees can grow, creating a positive feedback loop.

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By analyzing geographic data, comparing historical and recent photographs, and looking at tree rings, Kummel has been able to show that Pikes Peak’s tree line is advancing, likely due to regional changes in temperature. The tree line on Pikes Peak is between 12,300 and 12,600 feet, but used to be about 100 feet lower.

This movement is not unusual as tree lines around the world are rising due to increasing global temperatures. However, not all tree lines are advancing at the same pace.

Pikes Peak’s tree line is rising faster than many others, which can be associated with the mountain’s specific tree line form. The earliest aerial photos of Pikes Peak, going all the way back to 1938, show the tree line as an abrupt line across the mountain. It has since changed shape to a scattered edge going uphill. These types of tree lines around the world are advancing at the fastest pace, but it is unclear why.

One of the students, environmental science major Elizabeth (Betsie) Hopper ‘15, explains that by analyzing data on Pikes Peak’s tree line, “We can understand how other tree lines may advance with climate change, and interpret what the implications are of rising tree lines on the ecosystem as a whole.”

Kummel has now turned his attention to the microclimatic changes being put into motion by the advancing tree line, as well as the spatial properties of the moving front.

To collect large amounts of data, Kummel’s students from a previous summer helped construct a 33-foot meteorological tower that tracks wind speeds at various heights. Matt Zia ’14, Alyssa Fortune ’14, and Hopper have been making the trek out to the tower, as well as various soil and air temperature sensors spread throughout the area, a few times a week during the summer to collect and analyze the data.

Johanna Jensen ’14, Lauren Hebert ’14, and Rebekah (Becca) Barnett ‘15 are doing additional research on how pocket gophers change small areas of otherwise sparse alpine tundra into dense and highly productive patches of vegetation, and are helping out on the tree line research as well. Zia, Jensen, Hebert, and Barnett are environmental science majors, while Fortune is an environmental physics major.

At the moment Kummel and his students are interested in the various wind patterns found at tree line, which is where the bubbles come in. Starting at the ground level, and, with the assistance of some sturdy tree branches, Kummel works his way up to 12 feet in the air and releases the bubbles; the students then observe the bubbles' movements. The students are now brainstorming the best way to quantify their observations and understand how the various wind patterns affect soil conditions and tree growth.

The students will continue to collect data through Block One before most of the equipment is stashed away on the mountain until next summer, when the research continues. It has yet to be decided if the soil sensors will be left there in order to compile a full calendar year of data. The group is hoping to publish a paper sometime next year using the data that has been collected over the previous four summers.

For the students, the team work has been as rewarding as the discoveries. “It's really a long-term project that's been successful because so many dedicated people have worked on it and have been willing to explore all the facets of the tree line dynamics, from differences in soil heat to the bubble and air movement experiment that we're currently exploring,” Zia said.