Background: Management strategies have been proposed to minimise the effects of climate
change on forest resilience.
Aims: We investigated the Pacific Northwest US region forest carbon balance under current
practices, and changes that may result from management practices proposed for the region’s
34 million ha of forests to mitigate climate change effects.
Methods: We examined the relationship between NPP and biomass, using plot data, and
estimated the effects of proposed clear-cut harvest of young mesic forests for wood products
and bioenergy while preserving mesic mature/old forests for biodiversity (Sparing), thinning all
forests (Sharing), and a combination of sparing mesic mature and old, clearing mesic young,
and thinning dry forests (Sparing/Sharing).
Results: The forests of the region were found highly productive (NPP 163 Tg C year⁻¹) and a
strong carbon sink with NEP of 45 Tg C year⁻¹. Observations indicated the relationship between
NPP and biomass was not significantly different for thinned versus unthinned stands, after
accounting for site quality and precipitation effects. After simulating proposed management to
mitigate climate change, regional NPP was reduced by 35% (Sparing), 9% (Sharing), and 29%
(Sparing/Sharing) compared with current practices.
Conclusions: Applying management practices appropriate for current forest conditions to
mitigate future climate change impacts can be accomplished, but at a cost of reducing NPP.
Sparing all forests >50 years old resulted in the largest NPP reduction, but the impact could be
reduced by clearing only a subset of young forests.Keywords: fire, harvest, drought, disturbance, forest carbon processe
