Root structure and function in an ecological context

The Wahl & Ryser paper represents a valuable contribution to revealing ecological patterns associated with root structure. There is a need to identify simple metrics in roots, as has been done with specific leaf area in leaves, which can be used to understand broad patterns of physiological and ecological plant traits. As plant processes are generalized to ecosystem, landscape and regional scales, such simple metrics become increasingly valuable. Currently, the identification of useful metrics in roots, such as tissue density and vessel diameter, is only in its infancy. How well the relationships Wahl & Ryser found in grasses will apply to other plant families still needs to be explored. Given the vast literature on comparative studies in leaves, critical examinations of how root structure relates to leaf structure and the ecology of the plant is long overdue.