Dr. Stallard studies how land-cover and climate change affect water movement through soils, weathering, and erosion, and how these, in turn, affect the composition and dispersal of dissolved and solid phases in rivers and trace gases in the atmosphere. His work includes natural and human-altered landscapes, in the Americas, Southeast Asia, and Africa, including most of the Amazon, Orinoco, Mississippi and Panama Canal Basins. He has pioneered the linking of the composition of river-borne materials to the geology, soils, landscape, vegetation, land use, and climate change through field observations and through the development of steady-state erosional models to link the composition of solid and dissolved erosion products. He has pioneered the analysis of terrestrial soil-erosion, nutrient loading, and sedimentation in the human-altered carbon and nutrient cycles. Other interests include designing techniques to rapidly assess remote tropical landscapes for research and conservation.