Overall, only 2.1% of the pine trees' rings and 1.3% of the juniper shrubs' rings were blue; the cells which hadn't lignified properly were mainly found at the end of growth rings, in latewood ...
‘Blue’ tree rings, which indicate that the cell walls of that year’s growth never lignified properly, show us when a summer was too cold for the plants to grow. The scientists identified blue rings ...
Since trees and shrubs can live for hundreds of years, identifying these blue rings allows us to spot cold summers in the past. By looking at pine trees and juniper shrubs from northern Norway ...