Canadian Forest Service Publications

Decline in net ecosystem productivity following canopy transition to late-succession forests. 2014. Taylor, A.R.; Seedre, M.; Brassard, B.W.; Chen, H.Y.H. Ecosystems 17(5): 778–791.

Year: 2014

Available from: Atlantic Forestry Centre

Catalog ID: 35576

Language: English

CFS Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1007/s1002-014-9759-3

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Abstract

Boreal forests are critical to the global carbon (C) cycle. Despite recent advances in our understanding of boreal C budgets, C dynamics during compositional transition to late-succession forests remains unclear. Using a carefully replicated 203-year chronosequence, we examined long-term patterns of forest C stocks and net ecosystem productivity (NEP) following stand-replacing fire in the boreal forest of central Canada. We measured all C pools, including understorey vegetation, belowground biomass, and soil C, which are often missing from C budgets. We found a slight decrease in total ecosystem C stocks during early stand initiation, between 1 and 8 years after fire, at -0.90 Mg C ha-1 y -1. As stands regenerated, live vegetation biomass increased rapidly, with total ecosystem C stocks reaching a maximum of 287.72 Mg C ha-1 y -1 92 years after fire. Total ecosystem C mass then decreased in the 140- and 203-year-old stands, losing between -0.50 and -0.74 Mg C ha-1 y -1, contrasting with views that old-growth forests continue to maintain a positive C balance. The C decline corresponded with canopy transition from dominance of Populus tremuloides, Pinus banksiana, and Picea mariana in the 92-year-old stands to Betula papyrifera, Picea glauca, and Abies balsamea in the 203-year-old stands. Results from this study highlight the role of succession in long-term forest C dynamics and its importance when modeling terrestrial C flux.

Plain Language Summary

Despite recent advances in our understanding of boreal forest carbon (C) budgets, C dynamics during compositional transition to late-succession forests remain unclear. Using a carefully replicated 203-year chronosequence, we examined long-term patterns of forest C stocks and net ecosystem productivity (NEP) following stand-replacing fire in the boreal forest of central Canada. We measured all C pools and found a slight decrease in total ecosystem C stocks during early stand initiation, between 1 and 8 years after fire. As stands regenerated, live vegetation biomass increased rapidly, with total ecosystem C stocks reaching a maximum of 287.72 Mg C•ha-1 92 years after fire. Total ecosystem C mass then decreased in the 140- and 203-year-old stands, losing between -0.50 and -0.74 Mg C•ha-1•yr-1, contrasting with views that old-growth forests continue to maintain a positive C balance. The C decline corresponded with canopy transition from dominance of Populus tremuloides, Pinus banksiana, and Picea mariana to Betula papyrifera, Picea glauca, and Abies balsamea. Results from this study highlight the role of succession in long-term forest C dynamics and its importance when modeling terrestrial C flux.

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