Fine Root Data at the Hubbard Brook Experimental Forest, 1998 and 2013 collections

We restored calcium to soils of a forested watershed at Hubbard Brook and measured the response of fine root biomass fourteen years after treatment. Fine root samples were collected in Watershed 1 and the Bear Brook Watershed reference forest, located to the west of Watershed 6, in 1998 (pre-Ca treatment) and in 2013. In this northern hardwood forest fine root (< 1 mm diameter) biomass declined significantly in the Ca addition treatment relative to pretreatment and reference forest conditions. The decline was greatest in the high-elevation hardwood zone of the watershed where soils are thinnest and most base poor. In that zone fine roots were distributed more shallowly after treatment than for reference conditions. We suggest that relatively higher tree C allocation to roots contributes to depressed aboveground productivity in acidified northern hardwood forest ecosystems.