Forest-atmosphere BVOC exchange in diverse and structurally complex canopies: 1-D modeling of a mid-successional forest in northern Michigan. (November 2015)

• Record Type: Journal Article
• Authors: Bryan, Alexander M.; Cheng, Susan J.; Ashworth, Kirsti; Guenther, Alex B.; Hardiman, Brady S.; Bohrer, Gil; Steiner, Allison L.
• Is Part Of: Atmospheric environment. Volume 120(2015)
• Page Start: 217
• Page End: 226
• Publication Date: 2015-11
• Subjects: Biogenic volatile organic compounds -- Canopy modeling -- Mixed forests -- Forest succession -- Tropospheric chemistry; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2015.08.094
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: 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. Highlights: Canopy structural heterogeneity on BVOC chemistry is assessed using a 1-D model. Uniform and variable vertical foliage compositions are compared. Heterogeneous canopy emits 34% more isoprene at one AmeriFlux site. Alterations in BVOC environment from succession are greater in heterogeneous canopy.