The reflectometry of leaf asymmetry is a novel approach in the bio-monitoring of tree health in urban or
industrial habitats. Leaf asymmetry responds to the degree of environmental pollution and reflects
structural changes in a leaf due to environmental pollution. This paper describes the boundary conditions
to scale up from leaf to canopy level reflectance, by describing the variability of adaxial and abaxial leaf
reflectance, hence leaf asymmetry, along the crown height gradients of two tree species. Our findings
open a research pathway towards bio-monitoring based on the airborne remote sensing of tree canopies
and their leaf asymmetric properties.