Possible link between photosynthesis and leaf modulus of elasticity among vascular plants: a new player in leaf traits relationships?

A compromise between carbon assimilation and structure investment at the leaf level is broadly accepted, yet the relationship between net assimilation per area (A(n)) and leaf mass per area has been elusive. We propose bulk modulus of elasticity (epsilon) as a suitable parameter to reflect both leaf structure and function, and an inverse relationship between epsilon and A(n) and mesophyll conductance (g(m)) is postulated. Using data for A(n), g(m) and epsilon from previous studies and new measurements on a set of 20 species covering all major growth forms, a negative relationship between A(n) or g(m) and epsilon was observed. High epsilon was also related to low leaf capacitance and higher diffusive limitations to photosynthesis. In conclusion, epsilon emerges as a key trait linked with photosynthetic capacity across vascular plants, and its relationship with g(m) suggests the existence of a common mechanistic basis, probably involving a key role of cell walls.