Canadian Forest Service Publications

Empirical and Predicted Boreal Forest Carbon Pools Following Stem-Only Harvesting in Quebec, Canada. 2019. Sage, L. K., Smith, C.T., Kurz, W., Thiffault, E., Paré, D., Bernier, P. Soil Sci. Soc. Am. J. 83(Suppl1):S59-S81.

Year: 2019

Issued by: Pacific Forestry Centre

Catalog ID: 39931

Language: English

CFS Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.2136/sssaj2018.07.0283

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Abstract

Climate change and global wood products demand raise concerns about boreal forest ecosystem resilience to natural disturbances and harvesting. A chronosequence experiment located in Forêt Montmorency, Quebec was used to evaluate the effects of harvesting on carbon (C) recovery trajectories at the stand level over a period of 77 years in balsam fir-white birch stands. Empirical estimates of 19 Forêt Montmorency forest carbon pools were compared with those simulated by the Carbon Budget Model (CBM-CFS3) to test model assumptions for predicting carbon dynamics in this forest. The model was initialized using forest inventory data, spatially explicit environmental conditions, and disturbance matrices designed to represent historical spruce budworm epidemics in Forêt Montmorency. Over the chronosequence, total ecosystem C increased significantly (p = 0.05) following harvest from 211 Mg in year-zero to 279 ± 8 Mg C ha–1 in year 67 (mean ± SE), suggesting that FM carbon pools were recovering to pre-harvest levels after seven decades. The CBM-CFS3 model predicted total ecosystem C stocks within 10% of the empirical mean at stand maturity; however, several predicted C pools deviated from field observations in both C amounts and trends over time. The greatest differences were in deadwood and soil C pools, suggesting that model initialization of dead organic matter pools did not adequately simulate the 1000-yr history of C-pool transfers and stand dynamics leading up to the harvest. Modifications to CBM-CFS3 initialization assumptions and default decay parameters may more accurately simulate long-term effects of natural disturbances on C pools for this forest region.

Plain Language Summary

Objectives: to document ecosystem C stock changes following harvesting and comparing empirical results with estimates modeled with CBM-CFS3. Key findings: • Total ecosystem carbon recovered to pre-harvest levels after seven decade; • Predicted and observed carbon pools differed most for deadwood and soil. • Modified CBM-CFS3 initialization and default decay parameters may improve accuracy. Impact: strong empirical results to demonstrate forest carbon stock recovery following harvesting and the time it takes for such recovery in a boreal forest ecosystem of Eastern Canada; good illustration of the capacity of CBM-CFS3 to represent aggrading ecosystem C stock changes. Show needs for improving the model representation of the dead wood and the soil C pools.