Canadian boreal forests and climate change mitigation1

摘要

Quantitative assessment of Canada's boreal forest mitigation potential is not yet possible, though the range ofmitigation activities is known, requirements for sound analyses of options are increasingly understood, and there is emergingrecognition that biogeophysical effects need greater attention. Use of a systems perspective highlights trade-offs betweenactivities aimed at increasing carbon storage in the ecosystem, increasing carbon storage in harvested wood products (HWPs), orincreasing the substitution benefits of using wood in place of fossil fuels or more emissions-intensive products. A systemsperspective also suggests that erroneous conclusions about mitigation potential could result if analyses assume thatHWPcarbonis emitted at harvest, or bioenergy is carbon neutral. The greatest short-run boreal mitigation benefit generally would beachieved by avoiding greenhouse gas emissions; but over the longer run, there could be significant potential in activities thatincrease carbon removals. Mitigation activities could maximize landscape carbon uptake or maximize landscape carbon density,but not both simultaneously. The difference between the two is the rate at which HWPs are produced to meet society's demands,and mitigation activities could seek to delay or reduce HWP emissions and increase substitution benefits. Use of forest biomassfor bioenergy could also contribute though the point in time at which this produces a net mitigation benefit relative to a fossilfuel alternative will be situation-specific. Key knowledge gaps exist in understanding boreal mitigation strategies that are robustto climate change and how mitigation could be integrated with adaptation to climate change.