|Title||Forest-atmosphere BVOC exchange in diverse and structurally complex canopies: 1-D modeling of a mid-successional forest in northern Michigan|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||Bryan, Alexander, Cheng Susan J., Ashworth Kirsti, Guenther Alex B., Hardiman Brady S., Bohrer Gil, and Steiner Allison L.|
|Keywords||BIOGENIC VOLATILE ORGANIC COMPOUNDS, canopy modeling, forest succession, mixed forests, tropospheric chemistry|
Foliar emissions of biogenic volatile organic compounds (BVOC)—important precursors of tropospheric ozone and secondary organic aerosols—vary widely by vegetation type. Modeling studies to date typically represent the canopy as a single dominant tree type or a blend of tree types, yet many forests are diverse with trees of varying height. To assess the sensitivity of biogenic emissions to tree height variation, we compare two 1-D canopy model simulations in which BVOC emission potentials are homogeneous or heterogeneous with canopy depth. The heterogeneous canopy emulates the mid-successional forest at the University of Michigan Biological Station (UMBS). In this case, high-isoprene-emitting foliage (e.g., aspen and oak) is constrained to the upper canopy, where higher sunlight availability increases the light-dependent isoprene emission, leading to 34 % more isoprene and its oxidation products as compared to the homogeneous simulation. Isoprene declines from aspen mortality are 10 % larger when heterogeneity is considered. Overall, our results highlight the importance of adequately representing complexities of forest canopy structure when simulating light-dependent BVOC emissions and chemistry.