Robert J. (Bob) Luxmoore – Soil Physicist, Plant Physiologist, Forester, Pioneer Elevated CO2 Researcher, Modeler, Activist, Mentor and Colleague.

In 1981, Bob wrote a short letter to BioScience (39:626) responding to an important paper by Paul Kramer concerning how forests might respond to increasing atmospheric CO₂. Bob suggested a simple scheme, based on some model inferences, whereby nutrient limitations to CO₂ response might be circumvented. His ideas about root exudation and plant-microbe-nutrient interactions are common research topics now, but they were very novel ideas in 1981. Bob’s letter was a little bit crazy and a little bit provocative (“another Carboniferous Age!”), but it initiated Oak Ridge National Laboratory’s research program on forest response to elevated CO₂. The DOE project that started in October, 1981, continues today, and has brought in many millions of dollars of funding, led to well over 100 publications, and touched the careers of many including us four.  While wearing his soil physics hat, he initiated new research in soil physics that advanced the concepts of mesopores as a pore-size class between macropores and micropores, which he proposed, played a critical role in water flow and solute transport. Bob’s wardrobe of “hats” was uncommonly large, and wearing his modeling hat he contributed to both model development and application, including considerations of how soil-plant models could be used to translate fine-scale process observations to larger spatial and temporal scales. As an empirical forester and ecologist, Bob also dreamt of large scale warming studies that he never got to build himself, but that represented the seeds for the true ecosystem scale warming studies that have now begun in northern Minnesota. Bob served the scientific community as a mentor, a SSSAJ Editor, SSSA President, and Fellow. Away from his official professional duties Bob also volunteered his efforts in support of environmental issues and concerns in the east Tennessee area. We will present highlights from Bob’s career to enlighten those that didn’t have the pleasure of his company.