Persistence pays off for an REU student researching change in the alpine

Network News Fall 2014, Vol. 27 No. 3

Have you ever wondered what a Research Experience for Undergraduates (REU) with the Long Term Ecological Research (LTER) Network can do for a student? Well, Adam Formica can tell you. Now a Kellett Fellow in Geography at the University of Oxford, Formica is first author on a recent paper showcasing his REU project on a dramatic case of willow growth in the alpine, a project he credits for helping to shape his career trajectory.

Formica undertook his formative REU in the lab of Katharine Suding, incoming lead scientist for the Niwot Ridge (NWT) LTER and associate professor in the Department of Ecology and Evolutionary Biology (EBIO) and the Institute for Arctic and Alpine Research (INSTAAR) at the University of Colorado-Boulder (CU). The Suding lab uses experimental manipulations of snowpack, temperature and nitrogen deposition to understand changes in alpine vegetation, including the recent rash of willows on the Niwot Ridge.

“The increase in willow cover on Niwot is the most substantial vegetation change that has occurred at the site over the last several decades,” said Suding. “By combining long-term patterns with experiments, Adam was able to show that willow growth is likely due to changes in land use and the environment corresponding to the termination of grazing by sheep and the increase in both nitrogen deposition and snow.” The paper by Formica, Suding and colleagues traces six decades of alpine willow expansion ( It was published this year in the peer-reviewed journal Arctic, Antarctic and Alpine Research.

Formica analysed a time series of aerial photographs to demonstrate that willow cover is growing exponentially across an 18-hectare area at 3,500 meters elevation, expanding by 441 percent over the past 62 years.  He emphasized the role of global change in willow encroachment, as well as the potential for more willows to store more carbon, sequestering a primary constituent of greenhouse gas.

Formica acknowledged the role the REU program, funded by the National Science Foundation, played in preparing him for the work he has undertaken at Oxford. Here are some highlights from his interview with Chris Ray for the LTER Newsletter, in which Formica makes it clear that persistence pays off in many avenues—for students conducting research, for LTER sites gathering data, and for willows climbing a mountain.

How did you land the REU position in Katie Suding’s lab?

I applied to the Niwot Ridge REU but wasn’t accepted the first time around. I instead interned that summer at the Cedar Creek LTER, weeding the big biodiversity experiment there and pursuing a project [on] leaf nutrient levels in oak trees to examine their potential to take up groundwater pollutants in city parks. While sampling leaves in a park, I met Katie’s former lab tech, Charlotte Riggs, who referred me to Emily Farrer, one of Katie’s post-docs. When I first called Emily she told me that I was second in line for the REU but fortunately she found funding for a second REU student. Persistence pays off!

What led you to the question you decided to tackle for your summer project?

Once you climb above tree-line, willows are the most prominent vegetation on Niwot Ridge. Bill Bowman [Director of the CU Mountain Research Station and Professor in EBIO and INSTAAR] showed me an unpublished manuscript by the late Front Range naturalist and historian Jim Benedict with repeat photos from the 1940’s and the 2000’s depicting the dramatic growth of willows. There was ample anecdotal evidence of expanding willows, but no one had yet quantified the change. Katie’s lab had unpublished data on the effects of temperature, nitrogen, and snowpack on willow growth and survival as well as the above- and below-ground biomass and carbon content of willows. Armed with these data, I could not only trace how much willows were expanding, but start to explain why, and estimate how much carbon they would store.

How did you decide on your methods?

Faced with the challenge of quantifying willow cover before people were taking on-the-ground measurements, I had to resort to indirect ways of tracking willow cover through time. I was introduced to GIS at Cedar Creek when mapping the nutrient contents of oak leaves to look for spatial patterns and became fascinated by the ability to visualize and assess data in this way. Geo-referenced aerial photos of Niwot Ridge going back to the 1930’s were released during my REU summer. They were the longest-term vegetation data I had available. By specifying pixels that appeared to be the crowns of willow shrubs where they were known to grow, I was able to classify willow cover in photos at multiple time points. I then matched the willow cover trend with data on trends in potential drivers to examine what was behind the expansion of willows.

Were there any unforeseen challenges to completing your work?

I didn’t anticipate that my interests would shift while I was working on the project, but as I was exposed to more coursework in my third and fourth years in college, I was drawn to other questions. Despite these distractions I managed not to let go of my work on willows. The project anchored my studies, leading me to take courses in statistics and remote sensing to apply to my research. Working towards a publication provides excellent motivation for deepening your applied skills when you know your analyses must pass through review. There’s less room for error when you’re treated as a scientific peer and not just a student.

Were there any surprising results or methodological lessons?

I was surprised to learn that while willows are on the rise at Niwot, they are declining elsewhere in the Rocky Mountains, in part because of grazing pressure by elk. Ecosystems are complex so we expect to see variation. An ecologist’s job is to attempt to explain why and to formulate a hypothesis about the mechanism underlying the trend and discuss its implications. In the early drafts of the paper the emphasis was on drawing a comparison between shrub expansion in the arctic and the alpine tundra, pointing out that it was interesting this change was occurring in both places. The causes and consequences of shrub expansion in the alpine tundra, however, were of greater relevance. We elaborated on the causes and consequences by looking at where and how shrubs were expanding; how changes in temperature, precipitation, and nutrients influence shrub growth; and what shrub expansion might mean for the carbon balance of the alpine tundra. The next step will be to examine whether the same factors are driving increases in willows at other sites.

Were you surprised by any of the demands of the publication process?

The publication process took much longer than expected. After my summer of fieldwork at Niwot, I thought the hardest part of my research, gathering and analysing data, was over. The majority of the time I invested in the paper turned out to be in drafting and redrafting the presentation of my results. What I expected to take a year ended up taking three. One lesson I took away was to write down in detail all of your steps and to clearly label your data files and folders. If you don’t stay organized, you may come back in six months scratching your head wondering where exactly you put a dataset or how you performed a certain type of analysis.

Did your REU experience influence your career plans?

Most immediately, the REU at Niwot Ridge studying shrub expansion led me to my next REU at Toolik Lake, Alaska, to study shrubs in the Arctic. Shrub expansion is already well established there, so my aim was to test how a taller and denser shrub canopy might affect ecosystem level carbon cycling. In the long run, though, gaining experience with piecing together environmental data to make an argument about how an ecosystem behaved helped me realize what I found most exciting about the scientific process. There’s a vast amount of ecological data being collected every second by hand, sensor, drone, and satellite. My REU at Niwot showed me that pulling together all of this data and making sense of it to answer questions at multiple ecological scales is what I’d like to dedicate my career to. The questions that are gripping me now are how we can use data on ecosystems to improve the lives of people and to protect the diversity of species and landscapes for their own intrinsic value.

What are you researching now?

I’ve made a slight move from ecology to conservation. The two fields are intimately related; you can’t conserve ecosystems without knowing how they function. My current research focuses on a global scheme known as Reducing Emissions from Deforestation and Degradation (REDD), by which carbon emitting countries and companies pay landowners in forested regions to keep carbon locked up in their trees to mitigate climate change. I’m studying the overlap between carbon and other valuable landscape features such as biodiversity and the provisioning of clean water to help prioritize among sites chosen for carbon sequestration. Understanding the spatial relationships among environmental benefits will help decision makers optimize for the protection of those which they deem most important.

What was most interesting about working on Niwot Ridge?

I was fortunate to work at Niwot Ridge because it had an abundance of long-term data. Ecosystems are dynamic and sometimes picking up meaningful signals requires collecting many years of data. Luckily, I had long-term data from historical photos, meteorological stations, and vegetation surveys. Another great feature about Niwot is the collaboration of so many scientists in studying one site. Perhaps understated in the paper is how the expansion of willows might affect other species that rely on them at Niwot. For example, ptarmigan birds feed on willow buds that poke through the snow, and the snow that the willows trap insulates them from cold winter temperatures. A comprehensive study of ecosystems is beyond the scope of any one scientist because there are so many interacting variables. With so many scientists studying particular aspects of the alpine tundra at Niwot, they can share their results to give a more complete picture of the ecosystem.

What do you think is the most important message from your willow research?

When we’re studying the effects of global change we have to be sensitive to land use history. Many people view Niwot Ridge as pristine alpine habitat, yet only 60 years ago the area used to be heavily grazed by sheep. Willows may be bouncing back because sheep are no longer munching on their seedlings. Climate warming, nitrogen fertilization, and increased winter snowpack could also be contributing to the uptick in willows. Disentangling the influence of grazers and global change on willows is difficult. More generally, we should be aware that changes we are observing in an ecosystem now may have been triggered by events many decades ago. This is true particularly in harsh environments where vegetation takes such a long time to grow.