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 The
trail has turned to the left and climbed up the slope slightly. We have stayed
on the left fork and continued through the stands of yellow poplar and white
ash. A fallen white ash lays across the trail. It has been cut to allow easy
passage along the trail. On the cut ends of the white ash log you can see the
tree's "growth rings." These annual growth rings individually represent the
yearly cycle of encircling tissue growth (the "vascular cambium" whose principle
function is to transport water up the tree) and its inevitable change into
strong, supportive wood. A freshly cut tree's age can be accurately determined
by counting these growth rings. Further, under certain conditions the relative
widths of a tree's growth rings may indicate how "good" or "bad" a particular
growing season was. This analysis of ring widths, then, is a tool that can be
potentially used to explore the past climatic history of a site through the life
spans of its trees. Further, the patterns of these annual rings observed in
wooden artifacts (like building materials, wooden tools etc) can be matched up
by archeologists to ring patterns of surrounding trees thus enabling a very
precise dating of these objects .
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The Pennsylvania State University ©2002 This page was last updated on July 8, 2009
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The
fallen white ash tree in front of us has many annual growth rings. Judging by
the condition of the trunk and the absence of moss etc growing on the downed
tree, we estimate that this tree fell no more than five years ago.
