By counting the dark ring segments, scientists can tell a tree’s age if the cross section of the trunk is complete. Based at the University of Arizona in Tucson, Douglass wanted to know how sun spot activity affected climate, and his research soon led him to pioneering tree-ring analysis.Because the width of tree rings varies with growing conditions, scientists also learn about local climate during the tree’s lifetime by comparing the rings’ different widths. For instance, higher rainfall and a longer growing season produces a wider ring than a year with low rainfall and prolonged cold. Douglass was among the first to notice that trees in a geographic area develop the same growth-ring patterns because they experience the same climatic conditions.
Dendrochronology uses the variations in the thickness of annual growth rings in living trees as well as old timbers to date wooden objects and buildings, by counting tree-rings back from the present on very old trees and then by successively overlapping even older timbers further back through time.
The American botanist, Douglas, established the first tree-ring chronology in 1929 with a pine chronology for the south-west of America extending back to 701 AD.
(den-droh-cruh-NOL-uh-gee) means “the study of tree time.” Usually called tree-ring dating, dendrochronology is a science based on the fact that every growth season a tree adds a new layer of wood to its trunk.
Over time, these yearly growth layers form a series of light and dark concentric circles, or tree rings, that are visible on cross sections of felled trees.
This, in turn, let him determine the year each tree started growing.
The calculation was straightforward: count the dark rings inward and subtract that number from the year the tree was cut.
Numerous reference chronologies have been developed, and through statistical analysis it is generally possible to date timbers from over most of the UK.
However, different regions of the country experienced different climate, and dating may be problematic in some areas where the reference chronology coverage is weak and still in the process of development.
Dendrochronology is a science of precise dating, by the accurate counting of annual tree growth-rings, which allows dating wooden items to the year.
The pattern of annual tree-rings differs each year, depending upon the growing conditions at the time.
This results in the cambium cells becoming smaller and thicker-walled.