ARCHIVED CONTENT: In December 2020, the CZO program was succeeded by the Critical Zone Collaborative Network (CZ Net) ×

Arthur H. Johnson


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Soil Science

Professor and Graduate Chair; Department of Earth and Environmental Science; University of Pennsylvania

Ph.D.; 1975; Cornell University, Cornell University

Our research program addresses nutrient cycling in forests, primarily (1) the proximate and ultimate sources of macronutrients necessary for forest growth, and (2) the role of nutrients in limiting growth. As a new undertaking, we began a study of mummified forests of Eocene age (42 Ma) in the Canadian High Arctic. The exceptional preservation of the wood, litter, seeds, roots, cones and soils of these floodplain forests presents a unique opportunity to view life at a time when the planet was much warmer (and more productive).

CZO Research Groups


CZO Publications