Water, Air, and Soil Pollution

, Volume 70, Issue 1, pp 163–176

Conntribution of northern forests to the global C cycle: Canada as a case study

  • Werner A. Kurz
  • Michael J. Apps
Part III Workshop Research Presentations Section 1: Forest Systems

DOI: 10.1007/BF01104994

Cite this article as:
Kurz, W.A. & Apps, M.J. Water Air Soil Pollut (1993) 70: 163. doi:10.1007/BF01104994


Boreal forests are exposed to periodic stand-replacing disturbances such as wildfire. Unchanging disturbance regimes in unmanaged forests result in an age-class structure in which the proportion of forest area is largest in the youngest age class and decreases exponentially in older age classes. The current (ca. 1970) age-class structure of Canadian forests contains a much smaller proportion of the forest area in each of the two youngest 20-yr age classes than in each of the next three age classes (i.e., the 40 to 99-yr age-classes). We hypothesize that more intensive disturbance regimes in the late 19th and early 20th centuries, compared to disturbances in the period 1920 to 1969, have resulted in this unusual age-class structure. The reduction in disturbance regimes has resulted in an increase of the average forest age and therefore an increase in total forest biomass carbon (C). This C sink is obtained without altering age-dependent growth or decomposition rates. If the average forest age of Canadian forests continues to increase, additional C sequestration of forests, (i.e., the C sink strength) will diminish. This result of a C sink in Canadian forest ecosystems is supported by more detailed C budget calculations for the year 1986.

Copyright information

© Kluwer Academic Publishers 1993

Authors and Affiliations

  • Werner A. Kurz
    • 1
  • Michael J. Apps
    • 2
  1. 1.ESSA Environmental and Social Systems Analysts Ltd.VancouverCanada
  2. 2.Forestry Canada, Northwest RegionEdmontonCanada