When we meet people in the woods, we are often asked if it is true that one can tell the age of a tree by counting its rings. We tell them that not only can age be determined but also that a glimpse at the tree's history can be found in the rings. In temperate regions, trees deposit a single layer of wood around their circumference every year. Dendrochronology (dendron = tree; chronos = time; logos = the study of) is the science that uses tree rings, dated to their exact year of formation, to analyze temporal and spatial patterns of various processes (e.g., biological, physical, or cultural). The width of a tree ring in a given year represents the radial-growth response of the tree to prevailing environmental conditions. The width of a tree ring can be determined by noting the pattern of earlywood and latewood cells that are produced during secondary or radial growth. During the early part of the growing season, trees often produce large, thin- walled cells, and during the later period of the growing season, they produce smaller, thicker- walled cells. Hence, an annual ring will contain both an earlywood and latewood portion. By measuring the distance from the earlywood boundary of one ring to the earlywood boundary of another ring, the amount of wood produced during a given year can be quantified. Dendrochronologists have used accurately dated and measured tree rings in various research arenas: forest dynamics, reconstruction of past climate, dating archeological sites, dating forest fires, and even forensics. Needless to say, dendrochronology is an exciting field with many subdisciplines sure to interest many students.1 The main tool for our study is an increment borer or "tree corer."

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1 - taken verbatim from American Biology Teacher, vol. 64 num. 9