The temperature responses of net photosynthesis of Pinus cembra needles at 2 180 m a.s.l. (krummholz belt; top), 2100 m a.s.l (tree line; middle), and 1 950 m a.s.l. (forest limit; bottom) assessed in fall (open symbols) and summer (closed symbols). Measurements were made under laboratory conditions at ambient CO₂, 1 200 μmol m⁻² s^{− 1} PPFD, and 70% of relative humidity.