Clark Wissler of the American Museum of Natural History can be credited as one of the first individual scientists to realize the importance of such naturally occuring rings in trees can be used to tell how old it is. Pith is found at the center of the tree stem, then rings can bee seen followed by a layer that insulates between what is called vascular cambium (the source of xylem and phloem) and the outer appearance of the tree, or its bark.
Each year a new layer of xylem is produced, thus giving us the tree rings we all can observe and count.
This is important to consider because useful trees for dendrochronology are often found near zones of their natural range.
The site selection principle recognizes that certain species of trees propagate and survive better in certain conditions than others do.
Dendrochronology (also called tree-ring dating) is a technique of dating past climatic changes through a study of tree ring growth.
Each year a tree adds a layer of wood (xylem) to its trunk and branches thus creating the annual rings we see when viewing a cross section.
The aggregate tree growth principle states that many conditions, both natural and human induced are responsible for any one tree-ring series growth pattern.Each field team should obtain the appropriate field supplies from their instructor and obtain 3 increment cores from white oak trees at the chosen field site.Please consult Field Methods for a detailed description of the field equipment, including its use and care, and the actual methods of core collection and preservation. The cores should next be mounted and glued in to increment core holders and then the surface prepared for study following the protocols outlined in Lab Methods.The principle of replication states the need of more than one stem radius per tree and more than one tree per site.Essentially samples will range up to many trees per site or even many sites of trees.