Representation of plant roots in Terrestrial Biosphere Models
Connecting plants to the soil environment, roots are key regulators of plant and ecosystem function. Yet representation of root function and the dynamics of root function are often limited in Terrestrial Biosphere Models (TBMs). A brief overview of root representation in TBMs will be given in the context of their key processes—water uptake, N uptake and C cycling—and the scales of operation of TBMs. Constrained by the structure of TBMs, root architecture is represented in a single vertical dimension, generally as the proportion of roots in each of a number of soil layers. A knowledge gap exists between the detailed understanding of root physiology and the cellular/organismal scale and understanding of root function at the ecosystem scale.
Illustrations of the current representation of roots and root function in TBMs will be presented from model-data intercomparisons. The consequences of the TBM representations of roots for water uptake, nitrogen uptake and interactions with elevated CO2 will be discussed and demonstrated.