Forests in northeastern North America (pictured) could thrive in a warmer climate.
How trees will react to a warmer environment is unclear; low average temperatures hamper their growth but higher temperatures can limit water availability. Loic D'Orangeville of the University of Quebec at Montreal in Canada and his colleagues used tree-ring data from more than 16,000 stands of black spruce (Picea mariana) across Quebec to track growth between 1960 and 2004. They found that north of a latitude of 49°N, increased temperature had positive effects on tree growth, despite the lower availability of water. Below that latitude, however, only an increase in water availability boosted tree growth.
Although boreal forests in central and western North America might be negatively affected by climate change, northeastern areas could act as a refuge for certain trees, the authors suggest.