Carbon implications of current and future effects of drought, fire and management on Pacific Northwest forests

• Mortality rates in PNW US forests (0.5–1.35%) are consistent with historical means.
• Wildfires do not greatly reduce forest C storage, which is mostly in soil and wood.
• Long rotations accumulate more carbon than short rotations, and reduce C emissions.
• Forest composition is likely to continue to change under future climate (e.g., BC).
• Recent models and remote sensing make them relevant to managers.

Climate change has already begun to impact the structure and function of forest ecosystems in the Pacific Northwest by altering the frequency, intensity, and duration of droughts and heat stress, with implications for widespread environmental and socio-economic change. A major realization is that accumulated physiological stress can ultimately lead to tree mortality and changes in species distributions, particularly in areas away from maritime influences. To ameliorate the effects of drought, insect outbreaks, and reduce the risk of crown fires, various strategies are being tested. To make some of these strategies economical, biomass is proposed as an alternative energy source. At the same time that an increase in harvesting is being considered, there is a desire to increase carbon sequestration by forests to offset, at least in part, greenhouse gas emissions. Assessments are needed to determine current and future impacts of climate change, and to evaluate management options while considering carbon storage benefits and sustainability of ecosystem structure and function. Here we provide an overview of research results from the Pacific Northwest region where forests dominate the landscape and contain among the highest biomass on earth. In this review, we present findings that challenge common assumptions, and suggest a way to predict outcomes of changes in climate and land management in the future. The approach includes the use of observation-driven land system models that integrate the extent that forests are vulnerable to climate change, management practices, and economic considerations. It also requires increased emphasis on in situ and remotely sensed observations and experiments to initialize and test the model, and to track trends in forest condition.