Tansley Review No. 59 Leaf boundary layers

Abstract

Studies of heat and mass exchange between leaves and their local environment are central to our understanding of plant‐atmosphere interactions. The transfer across aerodynamic leaf boundary layers is generally described by non‐dimensional expressions which reflect largely empirical adaptations of engineering models derived for flat plates. This paper reviews studies on leaves, and leaf models with varying degrees of abstraction, in free and forced convection. It discusses implecations of finding for leaf morphology as it affects – and is affected by – the local microclimate. Predictions of transfer from many leaves in plant communities are complicated by physical and physiological feedback mechanisms between leaves and their environment. Some common approaches, and the current challenge of integrating leaf‐atmosphere interactions into models of global relevance, are also briefly addressed. ContentsSummary477I.Introduction478II.Early studies479III.The formal description of leaf transfer480IV.Effects of turbulence on idealized shapes484V.Effects of aspect ratio and inclination486VI.Leaves and leaf models in forced convection491VII.Leaves and leaf models in mixed and free convection493VIII.Interpretation of leaf shape494IX.Leaves in plant canopies499X.Synopsis and conclusions502References502