Growth-climate Relations of Lodgepole Pine in the North Cascades National Park, Washington

Abstract

Information about the sensitivity of lodgepole pine to climate will allow forest managers to maximize growth, better understand how carbon sequestration changes over time, and better model and predict future ecosystem responses to climate change. We examined the effects of climatic variability during the 20th century on the growth of lodgepole pine along an elevation gradient in the North Cascades National Park, Washington. Multivariate analysis and correlation analysis were used to simplify growth patterns and identify climate-growth relations. Mid-elevation chronologies correlated negatively with growing season maximum temperature and positively with growing season precipitation. By contrast, high-elevation chronologies correlated positively with annual temperatures and winter Pacific Decadal Oscillation index. Projected increases in summer temperatures will likely cause greater soil moisture stress in many forested ecosystems and the potential of extended summer drought periods over decades may significantly alter spatial patterns of productivity, thus impacting carbon storage. The productivity of lodgepole pine likely will decrease at sites with shallow, excessively drained soils, south and west facing aspects, and steep slopes, but increase at high-elevation sites.