While continuing to work with undergraduate researchers as the director of the Harvard Forest Summer Research Program in Ecology (2004-2019), Aaron introduced the concept of foundation species to terrestrial ecology and investigated their role in diversity and ecosystem function in forests throughout the world. Throughout his academic career, he studied food-web dynamics and community ecology of wetlands and forests; the evolutionary ecology of carnivorous plants; the responses of plants and ants to global climate change; application of Bayesian statistical inference to ecological research and environmental decision-making; and the critical reaction of Ecology to Modernism. He has authored or co-authored over 250 scientific papers, dozens of book reviews and software reviews, and the books A Primer of Ecological Statistics (2004; 2nd edition 2012), A Field Guide to the Ants of New England (2012), Stepping in the Same River Twice: Replication in Biological Research (2017), Vanishing Point (2017), Carnivorous Plants: Physiology, Ecology, and Evolution (2018), Scaling in Ecology with a Model System (2021), Success in Navigating Your Student Research Experience: Moving Forward in STEMM (2022), and Success in Mentoring your Student Researchers: Moving STEMM Forward (2022). Aaron was the Associate Editor-in-Chief of Ecology (2002-2010), Editor-in-Chief of Ecological Monographs (2009-2015); a Senior Editor of Methods in Ecology and Evolution (2018-2021); and since 2021, has been the Executive Editor of Methods in Ecology and Evolution. In 2012 he was elected a Fellow of the Ecological Society of America, and in 2016 he was certified as a Senior Ecologist by the Ecological Society of America (certification renewed in 2021). In 2021, Aaron received a Humboldt Prize from the Alexander von Humboldt Foundation, which enabled him to engage in research in 2023 on statistical methodology and ecology writ large at the University of Freiburg (in collaboration with Prof. Dr. Carstenn Dormann).