Forest carbon stocks in Newfoundland boreal forests of harvest and natural disturbance origin I: field study

Abstract

Quantification of stand and forest C stocks in response to different disturbances is necessary to develop climate change mitigation strategies and to evaluate forest C accounting tools. Live tree, dead tree, woody debris (WD), stump, buried wood, and organic and mineral soil C stocks are described in chronosequences of black spruce ( Picea mariana (Mill.) BSP) (harvest and fire origin) and balsam fir ( Abies balsamea (L.) Mill.) (insect and harvest origin). The largest C stocks were found in mineral soil (≤179 Mg·ha–1), organic soil (≤123 Mg·ha–1), and live tree (≤93 Mg·ha–1) pools. Live tree C changed predictably with disturbance history and time since disturbance, increasing with forest age. Regeneration growth slowed under snags. Thinning accelerated production of larger trees but reduced site live tree C. Dead tree and WD C were temporally dynamic and strongly influenced by disturbance history and time since disturbance, but abundances in differently disturbed forests converged at low levels 40–60 years after disturbance. Only immediately following natural disturbances were there large amounts of snag C (26–30 Mg·ha–1). WD C was relatively abundant <3 years after harvesting (15–17 Mg·ha–1) and 31–36 years after natural disturbance (9 Mg·ha–1). Buried wood stocks were small, but comparable with WD stocks in some forests.