PiTS-1: Carbon Partitioning in Loblolly Pine after 13C Labeling and Shade Treatments

The Partitioning in Trees and Soil (PiTS) task was established with the objective of improving the C partitioning routines in existing ecosystem models by exploring mechanistic model representations of partitioning tested against field observations. We used short-term field manipulations of C flow, through 13CO2 labeling, canopy shading and stem girdling, to dramatically alter C partitioning, and resultant data are being used to test model representation of C partitioning processes in the Community Land Model (CLM4 or CLM4.5). The research was conducted on individual trees within a small existing stand of planted Pinus taeda L.(loblolly pine) on the University of Tennessee Forest Resources Research and Education Center in Oak Ridge, Tennessee.