Oak Ridge National Laboratory

Free-Air CO2-Enrichment Experiment

Data-Model Interactions
​

Data from ecosystem-scale Free-Air CO2 Enrichment experiments provide a unique opportunity to test model assumptions.

Belowground Harvest
​

​​We excavated two large soil pits by hand in each treatment ring in late June, 2009 at the conclusion of the ORNL FACE experiment. ​

Nutrient Cycling ​Throughout the Soil Profile

​We used isotope pool dilution to measure potential gross nitrogen cycling rates throughout the soil profile. ​

Digging Deeper

Experimental evidence from a diverse set of forested ecosystems indicates that CO2-enrichment may lead to deeper rooting distributions. 

Missing Links

​Our goal was to synthesize root- and soil-centric studies into an integrated understanding of belowground ecosystem processes. ​

Root-Derived Input
​to the Soil

We combined a long-term minirhizotron data set with continuous, root-specific measurements to assess carbon and nitrogen input from root mortality. 

Nitrogen Limitation

We found that the increased production of ephemeral roots under elevated [CO2] was most likely a mechanism for greater nitrogen acquisition in response to nitrogen limitation within the stand.

Root Decomposition

We combined root decomposition techniques with soil fractionation techniques to quantify the transfer of carbon and nitrogen from decomposing fine-root litter to relatively long-lived SOM.