Intensive measurements of turbulence statistics, above canopy fluxes and profiles of isoprene, CO₂, and water vapor have been taken over the last two summers at the University of Michigan Biological Station (UMBS - an AmeriFlux site) in Pellston, Michigan. The UMBS~flux site is a flat, fairly uniform predominantly aspen/oak stand in a rural area of the lower peninsula. Here the measurements are used to evaluate an analytical model for the relationship between scalar sources and concentration profiles in forest canopies proposed by Warland and Thurtell (Boundary Layer Meteorology, 2000, Vol. 96, pp. 453-471). This Lagrangian model uses profiles of turbulence statistics to derive a dispersion matrix that enables a description of scalar transport through a forest canopy and in the lower boundary layer. The quantitative agreement between the model and measurements and its potential for elucidating the measured characteristics of nighttime concentration profiles of isoprene will be discussed.