Based on measurements of short-term temperature responses in this study and others, the scientists expected that the plants would increase their respiration by nearly five times that much.

At two forest-research sites in Minnesota, scientists tested how the respiration rates of 10 different species of trees — from boreal and temperate forests — were affected by increases in temperature over a period of three to five years, using heating cables to warm some of the trees.

The trees were monitored in two conditions: ambient, and about 6 degrees warmer than that.

To demonstrate how the plants adapted to long-term temperature increases, the scientists compared three things: how much carbon dioxide the trees released in ambient conditions; how much the trees released in the warmer conditions; and how much carbon dioxide the trees released when they were exposed to the warmer temperature for a short period of time (minutes or hours).

When the scientists compared the results, they found that the trees that were acclimated to the warmer temperatures increased their carbon dioxide release by a much smaller amount than the trees that were only exposed to a short-term temperature increase of the same magnitude.