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.