The science of tree-ring analysis is called dendrochronology. Examining the rings in tree cross-sections from cookies or sample cores can tell you a lot about a tree, its history and the environmental conditions it grew under.
This infographic shows how the size and colour of tree rings can reveal a tree’s age and fibre quality, and it’s past history of disturbance by forest fires, insect outbreaks or extreme climate conditions.
A photo of a cross-section from a 218-year-old black spruce tree spread over two pages that shows 5 things you can learn from tree rings with close-ups: (1) you can tell tree age by counting the number of bands of light wood and dark wood, which represent one year of growth; (2) fire scars occur where a portion of the growing part of a tree is damaged by fire and the tree attempts to cover the wound with new growth; (3) defoliation of a tree by forest tent caterpillar creates white tree rings that are of lower density than the wood before defoliation and after recovery allowing researchers to note years of caterpillar outbreaks. This portion of the graphic also shows a 5mm tree core from a 60 year old aspen tree, noting that cores are more often used for tree ring analysis. (4) narrow tree rings found in many trees across the landscape in the same year can help scientists understand how the climate may be changing and affecting forest ecosystems over time. A narrow tree ring from 1984 shown in the image suggests dry soil conditions in late summer across parts of Canada’s eastern boreal forest. (5) microscopic views of tree rings can show irregularities in cells caused by stresses to the tree, which affect wood fibre quality and characteristics like density, sound absorption, strength and stiffness. This may make affected trees less suitable for specific products or end uses.
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