Carbon and nitrogen dynamics under alternative climate change and management scenarios in the Oregon Coast Range

Background/Question/Methods

Forests are a major component of the global carbon cycle, and scientists and managers are exploring the use of forest management options for climate change mitigation. In the highly productive forests of the Oregon Coast Range, climate change mitigation could take the form of different management strategies, including restricting harvest to maximize ecosystem carbon sequestration, or removing forest residue along with harvesting as a source of renewable woody biomass energy. However, the long-term consequences of bioenergy harvesting are unknown, particularly as Coast Range forests face novel conditions resulting from climate change. We used the LANDIS-II forest simulation model to project the impacts of climate change and management actions on above- and below-ground carbon and nitrogen dynamics in a small watershed in the northeastern Oregon Coast Range. We explored scenarios varying in future climatic conditions (including current climate and six scenarios of climate change) and management strategies (including two harvest rotation periods, conventional and biomass energy harvest intensities, and no harvest) to determine the effects of climate change and management on long-term forest dynamics.

Results/Conclusions

Simulations suggest that climate change may have little effect on forest carbon storage and productivity over the next century. Conifer production increased in winter and spring months with warming temperatures, but was offset by declining production in summer months due to increasing temperature and water stress, and nitrogen limitation. Carbon and nitrogen in soil and detrital material accumulated at a slower rate under conditions of climate change as respiration and decomposition increased. Harvesting residual material for bioenergy had little impact on tree productivity, detrital carbon, and soil carbon and nitrogen pools. Ongoing work will expand the study to the entire Oregon Coast Range, where we will incorporate landscape-scale disturbances and a wider variety of management scenarios across a diverse range of landownerships.