Acclimation of respiratory temperature responses in northern and southern populations of Pinus banksiana

• Temperature acclimation of respiration may contribute to climatic adaptation and thus differ among populations from contrasting climates. • Short-term temperature responses of foliar dark respiration were measured in 33-yr-old trees of jack pine (Pinus banksiana) in eight populations of wide-ranging origin (44-55°N) grown in a common garden at 46.7°N. It was tested whether seasonal adjustments in respiration and population differences in this regard resulted from changes in base respiration rate at 5°C (R ₅) or Q₁₀ (temperature sensitivity) and covaried with nitrogen and soluble sugars. • In all populations, acclimation was manifest primarily through shifts in R₅ rather than altered Q₁₀. R₅ was higher in cooler periods in late autumn and winter and lower in spring and summer, inversely tracking variation in ambient air temperature. Overall, R₅ covaried with sugars and not with nitrogen. Although acclimation was comparable among all populations, the observed seasonal ranges in R₅ and Q₁₀ were greater in populations originating from warmer than from colder sites. Population differences in respiratory traits appeared associated with autumnal cold hardening. • Common patterns of respiratory temperature acclimation among biogeographically diverse populations provide a basis for predicting respiratory carbon fluxes in a wide-ranging species.