Forest canopies are the locus for much of the exchange of matter and energy between the terrestrial biosphere and the atmosphere.  They can be thought of a living capacitors, modulating fluxes between the biotic and abiotic worlds.  Several crucial questions regarding the mechanisms underlying canopy control of these fluxes sit at the intersection of biology, chemistry, and physics.  We explore the impact of biological diversity on flux regulation and the manner(s) in which diversity does (and does not) play a role in such regulation.  Drawing on research involving carbon dioxide, water, hydrocarbons, ozone, and contaminants, we argue that for compounds whose exchange is mediated by stomata, understanding basic metabolism is the key to quantifying the importance of diversity and that for compounds whose exchange is primarily surficial there is usually a significant role of diversity. 

Results/Conclusions

We present data showing that products of primary metabolism tend to be exchanged in a manner independent of species-level diversity, but specific-specific parameters do regulate the exchange of secondary metabolism products.  This research has important implications for conservation and ecosystem-service analyses and for improving the ability of land-cover / land-use change models to be used in biosphere/atmosphere exchange research.