Extracellular Enzyme Activities in the Soil as the Dynamic Link Between the Nitrogen Cycle and Global Scale Terrestrial Carbon Storage.

Nutrient limitation places a fundamental constraint on the size of the terrestrial sink for atmospheric CO2 in both space and time. Because nutrients are bound to SOM, nutrient availability for primary production depends upon the rate decomposition. While we broadly recognize that SOM decomposition is driven by the quantity and chemistry of litter inputs, the composition and activity of the microbial community, and the physical environment, the ultimate constraint on decomposition is the production and activity of extracellular enzymes.  Hence it is at least theoretically possible to argue that very small spatial and temporal scale processes related to enzyme activity and nutrient acquisition affect very large spatial and temporal scale rates of terrestrial C uptake.  In this presentation, I will draw on experimental studies with elevated CO2 and changes in belowground C allocation to describe the basis for this theoretical argument and the data that can be used to support it.