Partitioning the Components of Soil Respiration in a Trenching Experiment at Harvard Forest 2009-2010

Total soil respiration (Rt) is a combination of autotrophic (Ra) and heterotrophic respiration (Rh). Several methods have been developed to tease out the components of Rt, such as isotopic analyses, and removing Ra input through tree girdling and root exclusion experiments. Trenching involves severing the rooting system surrounding a plot to remove the Ra component within the plot. This method has some potential limitations. Reduced water uptake in trenched plots could change soil water content, which is one of the environmental controllers of Rt in many ecosystems. Eliminating root inputs could reduce heterotrophic decomposition of SOM via lack of priming. On the other hand, the severed dead roots may temporarily increase available carbon substrate for Rh. We utilized the trenching method to partition the autotrophic and heterotrophic components of soil respiration in an oak dominated forest with the footprint of the LPH tower.