To study intraspecific variation, birch saplings were chosen from seven origin sites and transplanted to a different site to conduct a common garden experiment. These seven origin sites had different ranges of Annual Average Temperature (AAT) with the lowest being 1.1 °C and highest being 7.5 °C . The AAT of the transplantation site was higher than the seven origin sites (7.8 °C). Saplings from warmer origin sites ,with AAT closer to that of the transplantation site, showed higher Relative Growth Rate (RGR) as well as Specific Leaf Area (SLA). There was a significant relationship between RGR-AAT and SLA-AAT. For photosynthetic activity under two temperature conditions ( 20°C and 30°C), saplings from warmer origin sites showed higher Maximum rate of Photosynthesis (Pmax ) at 30°C whereas saplings from colder origin sites did not change Pmax values. A similar trend was also observed for Dark Respiration values under two temperature conditions. The observed results suggest that intra-specific variation will give some varieties of birch species an upper hand in adapting to higher AAT under global warming predictions. Plants that belong to higher temperature regions might be better able to adapt to future high AAT compared to plants from colder regions.