Up until the 1960s, there is a very close correlation between the density of growth rings in trees in northern latitudes and summer temperatures, but after this it starts to break down. (newscientist.com)
Not all tree species have the same number of annual growth rings that are active in the movement of water and mineral nutrients. (scientificamerican.com)
How do they separate the effects of moisture and temperature using growth rings? (climateaudit.org)