A plant ecophysiologist who has spent much of his career developing process-based models of how plants and ecosystem function in order to address questions ranging from physiological controls on the allocation of carbon and nitrogen within individuals to global feedbacks between terrestrial ecosystems and climate. His interests concern controls on terrestrial vegetation type, structure, and productivity over a wide range of time and space scales and the effects of vegetation on atmospheric processes through land surface energy partitioning and carbon fluxes. He develops numerical models in order to test our understanding of processes through the ability of these models to faithfully simulate real-world phenomena, as well as address concerns regarding the effects of global change on terrestrial ecosystems and potential future atmospheric feedbacks. He continues to develop an individual-based model of vegetation dynamics, HYBRID, with the aim of producing processed-based representations of land surface processes for coupling to global-scale atmospheric models. His current work is particularly concerned with the representation of physiological differences between plant types and species, the representation of competition, and the global-scale dynamics of biogeochemistry-climate interactions. He is also working on the development of simple approaches to modelling global climate-biogeochemistry feedbacks over different timescales.