Using the sections, they can then study the plant's history by looking at its rings. Tree ring data often is used to determine a tree's age, but it also reveals much more of the tree's life story. For example, differences in the widths of the rings can show relative growth for different years. This information can be related back to records of stream flow characteristics for those years. As a result of this comparison, scientists can determine exactly how flow patterns affect growth.
Some trees are scarred during periods of extreme flooding.
Scars appear as indentations in rings on the upstream side of the tree. They occur when debris slams into the tree as it surges downstream during a flood. Environmental scientists use tree ring cores to derive climate history. Arizona's widely varying conditions and the hard life of southwest species like mesquite result in irregular growth that makes it difficult to obtain a reliable core. Instead, researchers study slabs, like the one shown here.