The chief purpose of tree core sampling is its direct relation to tree ring dating (a science called dendrochronology). By removing a small sample of a tree’s core, scientists can look back into history throughout the entire life of the tree.
Why is this important?
Trees grow in layers for each growing season, producing a series of concentric rings (called growth rings) in its cross-section. Thicker rings indicate periods of large or rapid growth, whereas thinner rings depict times when the tree’s growth was relatively slow or minimal.
Weather, climate, soil properties (like pH balance), natural disasters, and annual rainfall directly impact the tree’s growth during a given period of time—be that a duration of a flood (or drought) or the entirety of a growing season. A tree’s growth rings speak of nearly every event that has affected it during the course of its lifetime.
But core sampling isn’t just for living trees. No, trees that are petrified (or are dead/partially-dead) can be studied using the carbon-dating process to analyze their core samples. These ancient trees can be traced back through time—sometimes hundreds or thousands of years—to when they were living, according to the presence of weakly-radioactive carbon in their cores.
How can scientists use this?
Assessing the conditions present during a tree’s life (especially if the tree is/was very old) can help scientists to better understand what the world was like at the time. Fires and other natural disasters hundreds (and even thousands) of years ago may have left scars on trees that we see today in lush forests. Indications of weather and climate from ages past help to improve the weather-predicting process and give us a better understanding of earth’s natural history.
Entire scientific and historical records have been pieced together using the data obtained from trees’ core samples.
One tree’s story, though, is often not good enough. Usually several trees are sampled from a given area so that “agreements” within the samples can give reliable information about past events. If one tree in a given area showed signs of stunted growth at a particular time, a scientist could infer that the tree may have been the victim of an isolated event (such as disease, a lightning strike, excessive damage, etc.); but if several trees showed signs of stunted growth at that time, he/she might infer that some wide-spread event affected the trees (like a fire, drought, flood, etc.)
What are some recent applications?
The growth behaviors of trees over time have been used to track the occurrences of specific chemical presences in groundwater. Recently (in a 2008 study), this sort of tracking was found to detect the presence of perchloroethene (a pollutant also known as PCE) in contaminated areas. More and more pollutants are becoming traceable due to the study of core samples. One doesn’t have to wait to see the nasty effects of pollution to act in prevention—instead the sampling of trees can allow scientists to act while something can still be done about it.
