Helen Brush ’25


Ecology and Evolutionary Biology

Project Title

Mechanisms of Shrubification in a Changing Arctic

Certificate(s): Applied and Computational Mathematics

I worked at the Toolik Field Station in the Alaskan Arctic to investigate the mechanisms driving increased shrub presence, or “shrubification,” in the Arctic tundra. This widely observed Arctic phenomenon can have local and large-scale consequences. Understanding the environmental drivers of shrubification is important for predicting the trajectory of this ecosystem under future climate scenarios as the Arctic rapidly warms. I helped to establish a manipulation experiment subjecting nearly 1,000 individual shrubs across 80 experimental plots to combinations of warming, lengthened growing season, and nutrient addition. In these plots, we conducted extensive phenological and physical measurements of the shrubs and surrounding soils and plant communities to track treatment effects. As this was my second summer working at Toolik, I practiced greater independence and contributed more meaningfully to conversations about experimental design and data analysis. Outside of the shrub experiment, I engaged with other members of the Toolik community, learning about their research and helping when they needed extra hands in the field. I gained a heightened appreciation for interdisciplinary work as we took approaches from multiple fields, including community ecology, soil chemistry, and mathematical modeling. Spending the summer in such awe-inspiring wilderness with wonderful people was a privilege that I’m very grateful for.

Internship Year


Project Category

Climate and Environmental Science


Levine Lab, Department of Ecology and Evolutionary Biology, Princeton University - Toolik Field Station, Fairbanks, Alaska


Jonathan Levine, J.N. Allison Professor in Environmental Studies, Professor of Ecology and Evolutionary Biology; Ruby An, Ph.D. candidate, Ecology and Evolutionary Biology