Biochemical limitations of An in response to needle temperature for (A) the southern seed source and (B) the northern seed source. An was modelled at Ca= 400 ppm by Farquhar modelling using measured gs and estimated gm from A–Ci. The response of An is defined by the minimum value of either Rubisco-limited (Ac) (solid curve) or RuBP regeneration-limited (Aj) net photosynthesis (dashed curve).