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).
Effects of a tectonically-triggered wave of incision on riverine exports and soil mineralogy in the Luquillo Mountains of Puerto Rico. Brocard G., Willenbring J.K., Scatena F.N., Johnson A.H. (2015): Applied Geochemistry
Linking geomorphology, weathering and cation availability in the Luquillo Mountains of Puerto Rico. Porder S., Johnson A.H., Xing H.X., Brocard G., Goldsmith S. PettRidge J. ( (2015): 10.1016/j.geoderma.2015.03.002
Controls on soil carbon stocks in El Yunque National Forest, Puerto Rico. Johnson A.H., Hao Xing Xing, Scatena F.N. (2014): SSSAJ
Soil phosphorus fractionation during forest development on landslide scars in the Luquillo Mountains, Puerto Rico. Frizano, F., Johnson, A.H., Vann, D.R., Scatena, F.N. (2002): Biotropica
Biomass and Nutrient Content of the Bisley Experimental Watersheds, Luquillo Experimental Forest, Puerto Rico, Before and After Hurricane Hugo. Scatena, F.N.; Silver, W.; Siccama, T.; Johnson, A., and Sánchez, M.J. (1993): Biotropica
Papers and books that explicitly acknowledge a CZO grant are highlighted in PALE ORANGE.
Migration of a slow wave of erosion and its effect on nutrient availability in a tropical rainforest: detrital 10Be signature and soil mineralogy, Luquillo CZO, Puerto Rico . Brocard G., Willenbring J., Johnson A., and Scatena F.N. (2014): EGU General Assembly 2014
Linking geomorphology, weathering and soil cations in the Luquillo Mountains of Puerto Rico. Porder, S. Johnson, A.H., Xing H., Brocard G.Y., Goldsmith S.T. (2013): 2013 Fall Meeting, AGU, San Francisco, Calif