Increasing temperatures across the region will cause a lengthening of the growing season and an increase in heat accumulation (measured as summer warmth index) during summer months. These changes could have profound effects on phenology, plant growth, water availability, and species distributions. July temperature isotherms and SWI have been used to help define vegetation distribution and potential for vegetation change across the boreal and arctic biomes. The northern limit of the boreal forest occurs approximately at the 12°C mean July isotherm and a SWI of 35°C mo, and strong linkages have been described between SWI and treeline advance. The southern boundary for the boreal forest occurs at approximately the 18°C July isotherm. [...]
